Merge branch 'maint'

* maint:
  erts: Document the +M<S>acul command line argument
  erts: Carrier pool information in allocator information
  erts: Use carrier pool for migration of carriers
  erts: Implement test case for carrier pool
  erts: Implement carrier pool
  erts: Fix type errors in info functions
  erts: Use Uint64 for call counts
  erts: Fix failing testcase alloc_SUITE:rbtree
  erts: Rename allocator aoffcbf to aoffcaobf
  erts: Remove unnecessary flag arguments in allocators
  erts: Remove SBMBC allocator
  erts: Add test for add_mbc and remove_mbc callbacks
  erts: Fix deallocation in removed carrier
  erts: Change naive list to rb-tree of carriers in AOFF allocator
  erts: Prepare aoff allocator for carrier migration
  erts: Make carrier header sizes customizable
  erts: Add "bestfit within carrier" for aoff allocator (aoffcbf)

Conflicts:
	erts/preloaded/ebin/erlang.beam

31 files changed, 3148 insertions, 1152 deletions

diff --git a/erts/doc/src/erts_alloc.xml b/erts/doc/src/erts_alloc.xml
index d0836a551d..a303ad18a6 100644
--- a/erts/doc/src/erts_alloc.xml
+++ b/erts/doc/src/erts_alloc.xml
@@ -75,10 +75,6 @@
        segments are allocated, cached segments are used if possible
        instead of creating new segments.  This in order to reduce
        the number of system calls made.</item>
-      <tag><c>sbmbc_alloc</c></tag>
-      <item>Allocator used by other allocators for allocation of carriers
-      where only small blocks are placed. Currently this allocator is
-      disabled by default.</item>
     </taglist>
     <p><c>sys_alloc</c> is always enabled and
       cannot be disabled. <c>mseg_alloc</c> is always enabled if it is
@@ -86,9 +82,7 @@
       allocators can be <seealso marker="#M_e">enabled or disabled</seealso>.
       By default all allocators are enabled.
       When an allocator is disabled, <c>sys_alloc</c> is used instead of
-      the disabled allocator. <c>sbmbc_alloc</c> is an exception. If
-      <c>sbmbc_alloc</c> is disabled, other allocators will not handle
-      small blocks in separate carriers.</p>
+      the disabled allocator.</p>
     <p>The main idea with the <c>erts_alloc</c> library is to separate
       memory blocks that are used differently into different memory
       areas, and by this achieving less memory fragmentation. By
@@ -106,20 +100,15 @@
       following does <em>not</em> apply to them.</p>
     <p>An allocator manages multiple areas, called carriers, in which
       memory blocks are placed. A carrier is either placed in a
-      separate memory segment (allocated via <c>mseg_alloc</c>), in
-      the heap segment (allocated via <c>sys_alloc</c>), or inside
-      another carrier (in case it is a carrier created by
-      <c>sbmbc_alloc</c>). Multiblock
+      separate memory segment (allocated via <c>mseg_alloc</c>), or in
+      the heap segment (allocated via <c>sys_alloc</c>). Multiblock
       carriers are used for storage of several blocks. Singleblock
       carriers are used for storage of one block. Blocks that are
       larger than the value of the singleblock carrier threshold
       (<seealso marker="#M_sbct">sbct</seealso>) parameter are placed
       in singleblock carriers. Blocks that are smaller than the value
       of the <c>sbct</c> parameter are placed in multiblock
-      carriers. Blocks that are smaller than the small block multiblock
-      carrier threshold (<seealso marker="#M_sbmbct">sbmbct</seealso>)
-      will be placed in multiblock carriers only used for small blocks.
-      Normally an allocator creates a "main multiblock
+      carriers. Normally an allocator creates a "main multiblock
       carrier". Main multiblock carriers are never deallocated. The
       size of the main multiblock carrier is determined by the value
       of the <seealso marker="#M_mmbcs">mmbcs</seealso> parameter.</p>
@@ -140,9 +129,7 @@
       <c>sbct</c> parameter should be larger than the value of the
       <c>lmbcs</c> parameter, the allocator may have to create
       multiblock carriers that are larger than the value of the
-      <c>lmbcs</c> parameter, though. The size of multiblock carriers
-      for small blocks is determined by the small block multiblock
-      carrier size (<seealso marker="#M_sbmbcs">sbmbcs</seealso>).
+      <c>lmbcs</c> parameter, though.
       Singleblock carriers allocated via <c>mseg_alloc</c> are sized
       to whole pages.</p>
     <p>Sizes of carriers allocated via <c>sys_alloc</c> are
@@ -183,6 +170,15 @@
           used. The time complexity is proportional to log N, where
           N is the number of free blocks.</p>
       </item>
+      <tag>Address order first fit carrier address order best fit</tag>
+      <item>
+        <p>Strategy: Find the <em>carrier</em> with the lowest address that
+	can satisfy the requested block size, then find a block within
+	that carrier using the "adress order best fit" strategy.</p>
+        <p>Implementation: Balanced binary search trees are
+          used. The time complexity is proportional to log N, where
+          N is the number of free blocks.</p>
+      </item>
       <tag>Good fit</tag>
       <item>
         <p>Strategy: Try to find the best fit, but settle for the best fit
@@ -219,11 +215,6 @@
        but can only satisfy a limited amount of requests.</p>
   </section>
 
-  <note><p>
-    Currently only allocators using the best fit and the address order
-    best fit strategies are able to use "small block multi block carriers".
-  </p></note>
-
   <section>
     <marker id="flags"></marker>
     <title>System Flags Effecting erts_alloc</title>
@@ -245,7 +236,6 @@
       the currently present allocators:</p>
     <list type="bulleted">
       <item><c>B: binary_alloc</c></item>
-      <item><c>C: sbmbc_alloc</c></item>
       <item><c>D: std_alloc</c></item>
       <item><c>E: ets_alloc</c></item>
       <item><c>F: fix_alloc</c></item>
@@ -319,10 +309,42 @@
        subsystem identifier, only the specific allocator identified will be
        effected:</p>
     <taglist>
-      <tag><marker id="M_as"><c><![CDATA[+M<S>as bf|aobf|aoff|gf|af]]></c></marker></tag>
+      <tag><marker id="M_acul"><c><![CDATA[+M<S>acul <utilization>|de]]></c></marker></tag>
+      <item>
+	Abandon carrier utilization limit. A valid
+	<c><![CDATA[<utilization>]]></c> is an integer in the range
+	<c>[0, 100]</c> representing utilization in percent. When a
+	utilization value larger than zero is used, allocator instances
+	are allowed to abandon multiblock carriers. Currently the default
+	is zero. If <c>de</c> (default enabled) is passed instead of a
+	<c><![CDATA[<utilization>]]></c>, a recomended non zero utilization
+	value will be used. The actual value chosen depend on allocator
+	type and may be changed between ERTS versions. Carriers will be
+	abandoned when memory utilization in the allocator instance falls
+	below the utilization value used. Once a carrier has been abandoned,
+	no new allocations will be made in it. When an allocator instance
+	gets an increased multiblock carrier need, it will first try to
+	fetch an abandoned carrier from an allocator instances of the same
+	allocator type. If no abandoned carrier could be fetched, it will
+	create a new empty carrier. When an abandoned carrier has been
+	fetched it will function as an ordinary carrier. This feature has
+	special requirements on the
+	<seealso marker="#M_as">allocation strategy</seealso> used. Currently
+	only the <c>aoff</c> and the <c>aoffcaobf</c> strategies support
+	abandoned carriers. This feature also requires
+	<seealso marker="#M_t">multiple thread specific instances</seealso>
+	to be enabled. When enabling this feature, multiple thread specific
+	instances will be enabled if not already enabled, and the
+	<c>aoffcaobf</c> strategy will be enabled if current strategy does not
+	support abandoned carriers. This feature can be enabled on all
+	allocators based on the <c>alloc_util</c> framework with the
+	exception of <c>temp_alloc</c> (which would be pointless).
+      </item>
+      <tag><marker id="M_as"><c><![CDATA[+M<S>as bf|aobf|aoff|aoffcaobf|gf|af]]></c></marker></tag>
       <item>
        Allocation strategy. Valid strategies are <c>bf</c> (best fit),
       <c>aobf</c> (address order best fit), <c>aoff</c> (address order first fit),
+      <c>aoffcaobf</c> (address order first fit carrier address order best fit),
       <c>gf</c> (good fit), and <c>af</c> (a fit). See 
       <seealso marker="#strategy">the description of allocation strategies</seealso> in "the <c>alloc_util</c> framework" section.</item>
       <tag><marker id="M_asbcst"><c><![CDATA[+M<S>asbcst <size>]]></c></marker></tag>
@@ -416,20 +438,6 @@
        smaller than this threshold will be placed in multiblock
        carriers. On 32-bit Unix style OS this threshold can not be set higher
        than 8 megabytes.</item>
-      <tag><marker id="M_sbmbcs"><c><![CDATA[+M<S>sbmbcs <size>]]></c></marker></tag>
-      <item>
-	Small block multiblock carrier size (in bytes). Memory blocks smaller
-	than the small block multiblock carrier threshold
-	(<seealso marker="#M_sbmbct">sbmbct</seealso>) will be placed in
-	multiblock carriers used for small blocks only. This parameter
-	determines the size of such carriers.
-      </item>
-      <tag><marker id="M_sbmbct"><c><![CDATA[+M<S>sbmbct <size>]]></c></marker></tag>
-      <item>
-	Small block multiblock carrier threshold (in bytes). Memory blocks
-	smaller than this threshold will be placed in multiblock carriers
-	used for small blocks only.
-      </item>
       <tag><marker id="M_smbcs"><c><![CDATA[+M<S>smbcs <size>]]></c></marker></tag>
       <item>
        Smallest (<c>mseg_alloc</c>) multiblock carrier size (in
diff --git a/erts/emulator/beam/atom.names b/erts/emulator/beam/atom.names
index 9e12080732..7d86e486f1 100644
--- a/erts/emulator/beam/atom.names
+++ b/erts/emulator/beam/atom.names
@@ -323,6 +323,7 @@ atom maximum
 atom max_tables max_processes
 atom mbuf_size
 atom memory
+atom memory_internal
 atom memory_types
 atom message
 atom message_binary
diff --git a/erts/emulator/beam/erl_afit_alloc.c b/erts/emulator/beam/erl_afit_alloc.c
index b45201af42..eca4e3b3bb 100644
--- a/erts/emulator/beam/erl_afit_alloc.c
+++ b/erts/emulator/beam/erl_afit_alloc.c
@@ -48,10 +48,9 @@ struct AFFreeBlock_t_ {
 #define MIN_MBC_FIRST_FREE_SZ	(4*1024)
 
 /* Prototypes of callback functions */
-static Block_t *	get_free_block		(Allctr_t *, Uint,
-						 Block_t *, Uint, Uint32);
-static void		link_free_block		(Allctr_t *, Block_t *, Uint32);
-static void		unlink_free_block	(Allctr_t *, Block_t *, Uint32);
+static Block_t *	get_free_block		(Allctr_t *, Uint, Block_t *, Uint);
+static void		link_free_block		(Allctr_t *, Block_t *);
+static void		unlink_free_block	(Allctr_t *, Block_t *);
 
 
 static Eterm		info_options		(Allctr_t *, char *, int *,
@@ -84,8 +83,7 @@ erts_afalc_start(AFAllctr_t *afallctr,
 
     sys_memcpy((void *) afallctr, (void *) &zero.allctr, sizeof(AFAllctr_t));
 
-    init->sbmbct = 0; /* Small mbc not supported by afit */
-
+    allctr->mbc_header_size		= sizeof(Carrier_t);
     allctr->min_mbc_size		= MIN_MBC_SZ;
     allctr->min_mbc_first_free_size	= MIN_MBC_FIRST_FREE_SZ;
     allctr->min_block_size		= sizeof(AFFreeBlock_t);
@@ -100,6 +98,9 @@ erts_afalc_start(AFAllctr_t *afallctr,
     allctr->get_next_mbc_size		= NULL;
     allctr->creating_mbc		= NULL;
     allctr->destroying_mbc		= NULL;
+    allctr->add_mbc                     = NULL;
+    allctr->remove_mbc                  = NULL;
+    allctr->largest_fblk_in_mbc         = NULL;
     allctr->init_atoms			= init_atoms;
 
 #ifdef ERTS_ALLOC_UTIL_HARD_DEBUG
@@ -116,8 +117,7 @@ erts_afalc_start(AFAllctr_t *afallctr,
 }
 
 static Block_t *
-get_free_block(Allctr_t *allctr, Uint size, Block_t *cand_blk, Uint cand_size,
-	       Uint32 flags)
+get_free_block(Allctr_t *allctr, Uint size, Block_t *cand_blk, Uint cand_size)
 {
     AFAllctr_t *afallctr = (AFAllctr_t *) allctr;
 
@@ -135,7 +135,7 @@ get_free_block(Allctr_t *allctr, Uint size, Block_t *cand_blk, Uint cand_size,
 }
 
 static void
-link_free_block(Allctr_t *allctr, Block_t *block, Uint32 flags)
+link_free_block(Allctr_t *allctr, Block_t *block)
 {
     AFFreeBlock_t *blk = (AFFreeBlock_t *) block;
     AFAllctr_t *afallctr = (AFAllctr_t *) allctr;
@@ -156,7 +156,7 @@ link_free_block(Allctr_t *allctr, Block_t *block, Uint32 flags)
 }
 
 static void
-unlink_free_block(Allctr_t *allctr, Block_t *block, Uint32 flags)
+unlink_free_block(Allctr_t *allctr, Block_t *block)
 {
     AFFreeBlock_t *blk = (AFFreeBlock_t *) block;
     AFAllctr_t *afallctr = (AFAllctr_t *) allctr;
diff --git a/erts/emulator/beam/erl_alloc.c b/erts/emulator/beam/erl_alloc.c
index 403776aade..a547191d6d 100644
--- a/erts/emulator/beam/erl_alloc.c
+++ b/erts/emulator/beam/erl_alloc.c
@@ -71,6 +71,23 @@
 #define AU_ALLOC_DEFAULT_ENABLE(X)	(X)
 #endif
 
+#define ERTS_ALC_DEFAULT_ENABLED_ACUL 60
+#define ERTS_ALC_DEFAULT_ENABLED_ACUL_EHEAP_ALLOC 45
+#define ERTS_ALC_DEFAULT_ENABLED_ACUL_LL_ALLOC 85
+
+#define ERTS_ALC_DEFAULT_ACUL 0
+#define ERTS_ALC_DEFAULT_ACUL_EHEAP_ALLOC 0
+#define ERTS_ALC_DEFAULT_ACUL_LL_ALLOC 0
+
+#ifndef ERTS_SMP
+#  undef ERTS_ALC_DEFAULT_ACUL
+#  define ERTS_ALC_DEFAULT_ACUL 0
+#  undef ERTS_ALC_DEFAULT_ACUL_EHEAP_ALLOC
+#  define ERTS_ALC_DEFAULT_ACUL_EHEAP_ALLOC 0
+#  undef ERTS_ALC_DEFAULT_ACUL_LL_ALLOC
+#  define ERTS_ALC_DEFAULT_ACUL_LL_ALLOC 0
+#endif
+
 #ifdef DEBUG
 static Uint install_debug_functions(void);
 #if 0
@@ -101,11 +118,9 @@ typedef union {
     char align_aoffa[ERTS_ALC_CACHE_LINE_ALIGN_SIZE(sizeof(AOFFAllctr_t))];
 } ErtsAllocatorState_t;
 
-static ErtsAllocatorState_t sbmbc_alloc_state;
 static ErtsAllocatorState_t std_alloc_state;
 static ErtsAllocatorState_t ll_alloc_state;
 #if HALFWORD_HEAP
-static ErtsAllocatorState_t sbmbc_low_alloc_state;
 static ErtsAllocatorState_t std_low_alloc_state;
 static ErtsAllocatorState_t ll_low_alloc_state;
 #endif
@@ -120,6 +135,7 @@ static ErtsAllocatorState_t fix_alloc_state;
 typedef struct {
     erts_smp_atomic32_t refc;
     int only_sz;
+    int internal;
     Uint req_sched;
     Process *proc;
     Eterm ref;
@@ -162,6 +178,7 @@ enum allctr_type {
 struct au_init {
     int enable;
     int thr_spec;
+    int carrier_migration_allowed;
     enum allctr_type	atype;
     struct {
 	AllctrInit_t	util;
@@ -200,7 +217,6 @@ typedef struct {
 	char *mtrace;
 	char *nodename;
     } instr;
-    struct au_init sbmbc_alloc;
     struct au_init sl_alloc;
     struct au_init std_alloc;
     struct au_init ll_alloc;
@@ -211,13 +227,12 @@ typedef struct {
     struct au_init driver_alloc;
     struct au_init fix_alloc;
 #if HALFWORD_HEAP
-    struct au_init sbmbc_low_alloc;
     struct au_init std_low_alloc;
     struct au_init ll_low_alloc;
 #endif
 } erts_alc_hndl_args_init_t;
 
-#define ERTS_AU_INIT__ {0, 0, GOODFIT, DEFAULT_ALLCTR_INIT, {1,1,1,1}}
+#define ERTS_AU_INIT__ {0, 0, 1, GOODFIT, DEFAULT_ALLCTR_INIT, {1,1,1,1}}
 
 #define SET_DEFAULT_ALLOC_OPTS(IP)					\
 do {									\
@@ -225,32 +240,13 @@ do {									\
     sys_memcpy((void *) (IP), (void *) &aui__, sizeof(struct au_init));	\
 } while (0)
 
-static void
-set_default_sbmbc_alloc_opts(struct au_init *ip)
+static ERTS_INLINE void
+set_default_acul(struct au_init *ip, int acul)
 {
-    SET_DEFAULT_ALLOC_OPTS(ip);
-    ip->enable			= 0;
-    ip->thr_spec		= 0;
-    ip->atype			= BESTFIT;
-    ip->init.bf.ao		= 1;
-    ip->init.util.ramv		= 0;
-    ip->init.util.mmsbc		= 0;
-    ip->init.util.mmmbc		= 500;
-    ip->init.util.sbct		= ~((UWord) 0);
-    ip->init.util.name_prefix	= "sbmbc_";
-    ip->init.util.alloc_no	= ERTS_ALC_A_SBMBC;
-#ifndef SMALL_MEMORY
-    ip->init.util.mmbcs 	= 2*1024*1024; /* Main carrier size */
-#else
-    ip->init.util.mmbcs 	= 1*1024*1024; /* Main carrier size */
-#endif
-    ip->init.util.ts 		= ERTS_ALC_MTA_SBMBC;
-    ip->init.util.asbcst	= 0;
-    ip->init.util.rsbcst	= 0;
-    ip->init.util.rsbcmt	= 0;
-    ip->init.util.rmbcmt	= 0;
-    ip->init.util.sbmbct	= 0;
-    ip->init.util.sbmbcs	= 0;
+    ip->thr_spec = 1;
+    ip->atype = AOFIRSTFIT;
+    ip->init.aoff.bf_within_carrier = 1;
+    ip->init.util.acul = acul;
 }
 
 static void
@@ -258,8 +254,12 @@ set_default_sl_alloc_opts(struct au_init *ip)
 {
     SET_DEFAULT_ALLOC_OPTS(ip);
     ip->enable			= AU_ALLOC_DEFAULT_ENABLE(1);
+#if ERTS_ALC_DEFAULT_ACUL
+    set_default_acul(ip, ERTS_ALC_DEFAULT_ACUL);
+#else
     ip->thr_spec		= 1;
     ip->atype			= GOODFIT;
+#endif
     ip->init.util.name_prefix	= "sl_";
     ip->init.util.mmmbc		= 5;
     ip->init.util.alloc_no	= ERTS_ALC_A_SHORT_LIVED;
@@ -282,8 +282,12 @@ set_default_std_alloc_opts(struct au_init *ip)
 {
     SET_DEFAULT_ALLOC_OPTS(ip);
     ip->enable			= AU_ALLOC_DEFAULT_ENABLE(1);
+#if ERTS_ALC_DEFAULT_ACUL
+    set_default_acul(ip, ERTS_ALC_DEFAULT_ACUL);
+#else
     ip->thr_spec		= 1;
     ip->atype			= BESTFIT;
+#endif
     ip->init.util.name_prefix	= "std_";
     ip->init.util.mmmbc		= 5;
     ip->init.util.alloc_no	= ERTS_ALC_A_STANDARD;
@@ -300,9 +304,13 @@ set_default_ll_alloc_opts(struct au_init *ip)
 {
     SET_DEFAULT_ALLOC_OPTS(ip);
     ip->enable			= AU_ALLOC_DEFAULT_ENABLE(1);
+#if ERTS_ALC_DEFAULT_ACUL_LL_ALLOC
+    set_default_acul(ip, ERTS_ALC_DEFAULT_ACUL_LL_ALLOC);
+#else
     ip->thr_spec		= 0;
     ip->atype			= BESTFIT;
     ip->init.bf.ao		= 1;
+#endif
     ip->init.util.ramv		= 0;
     ip->init.util.mmsbc		= 0;
     ip->init.util.mmmbc		= 0;
@@ -319,8 +327,6 @@ set_default_ll_alloc_opts(struct au_init *ip)
     ip->init.util.rsbcst	= 0;
     ip->init.util.rsbcmt	= 0;
     ip->init.util.rmbcmt	= 0;
-    ip->init.util.sbmbct	= 0;
-    ip->init.util.sbmbcs	= 0;
 }
 
 static void
@@ -329,6 +335,7 @@ set_default_temp_alloc_opts(struct au_init *ip)
     SET_DEFAULT_ALLOC_OPTS(ip);
     ip->enable			= AU_ALLOC_DEFAULT_ENABLE(1);
     ip->thr_spec		= 1;
+    ip->carrier_migration_allowed = 0;
     ip->atype			= AFIT;
     ip->init.util.name_prefix	= "temp_";
     ip->init.util.alloc_no	= ERTS_ALC_A_TEMPORARY;
@@ -351,8 +358,12 @@ set_default_eheap_alloc_opts(struct au_init *ip)
 {
     SET_DEFAULT_ALLOC_OPTS(ip);
     ip->enable			= AU_ALLOC_DEFAULT_ENABLE(1);
+#if ERTS_ALC_DEFAULT_ACUL_EHEAP_ALLOC
+    set_default_acul(ip, ERTS_ALC_DEFAULT_ACUL_EHEAP_ALLOC);
+#else
     ip->thr_spec		= 1;
     ip->atype			= GOODFIT;
+#endif
     ip->init.util.mmmbc		= 100;
     ip->init.util.name_prefix	= "eheap_";
     ip->init.util.alloc_no	= ERTS_ALC_A_EHEAP;
@@ -374,8 +385,12 @@ set_default_binary_alloc_opts(struct au_init *ip)
 {
     SET_DEFAULT_ALLOC_OPTS(ip);
     ip->enable			= AU_ALLOC_DEFAULT_ENABLE(1);
+#if ERTS_ALC_DEFAULT_ACUL
+    set_default_acul(ip, ERTS_ALC_DEFAULT_ACUL);
+#else
     ip->thr_spec		= 1;
     ip->atype			= BESTFIT;
+#endif
     ip->init.util.mmmbc		= 50;
     ip->init.util.name_prefix	= "binary_";
     ip->init.util.alloc_no	= ERTS_ALC_A_BINARY;
@@ -392,8 +407,12 @@ set_default_ets_alloc_opts(struct au_init *ip)
 {
     SET_DEFAULT_ALLOC_OPTS(ip);
     ip->enable			= AU_ALLOC_DEFAULT_ENABLE(1);
+#if ERTS_ALC_DEFAULT_ACUL
+    set_default_acul(ip, ERTS_ALC_DEFAULT_ACUL);
+#else
     ip->thr_spec		= 1;
     ip->atype			= BESTFIT;
+#endif
     ip->init.util.mmmbc		= 100;
     ip->init.util.name_prefix	= "ets_";
     ip->init.util.alloc_no	= ERTS_ALC_A_ETS;
@@ -410,8 +429,12 @@ set_default_driver_alloc_opts(struct au_init *ip)
 {
     SET_DEFAULT_ALLOC_OPTS(ip);
     ip->enable			= AU_ALLOC_DEFAULT_ENABLE(1);
+#if ERTS_ALC_DEFAULT_ACUL
+    set_default_acul(ip, ERTS_ALC_DEFAULT_ACUL);
+#else
     ip->thr_spec		= 1;
     ip->atype			= BESTFIT;
+#endif
     ip->init.util.name_prefix	= "driver_";
     ip->init.util.alloc_no	= ERTS_ALC_A_DRIVER;
 #ifndef SMALL_MEMORY
@@ -428,8 +451,12 @@ set_default_fix_alloc_opts(struct au_init *ip,
 {
     SET_DEFAULT_ALLOC_OPTS(ip);
     ip->enable			= AU_ALLOC_DEFAULT_ENABLE(1);
+#if ERTS_ALC_DEFAULT_ACUL
+    set_default_acul(ip, ERTS_ALC_DEFAULT_ACUL);
+#else
     ip->thr_spec		= 1;
     ip->atype			= BESTFIT;
+#endif
     ip->init.bf.ao = 1;
     ip->init.util.name_prefix	= "fix_";
     ip->init.util.fix_type_size	= fix_type_sizes;
@@ -527,6 +554,39 @@ static void adjust_fix_alloc_sizes(UWord extra_block_size)
     }
 }
 
+static ERTS_INLINE int
+strategy_support_carrier_migration(struct au_init *auip)
+{
+    /*
+     * Currently only aoff and aoffcaobf support carrier
+     * migration, i.e, type AOFIRSTFIT.
+     */
+    return auip->atype == AOFIRSTFIT;
+}
+
+static ERTS_INLINE void
+check_disable_carrier_migration(struct au_init *auip)
+{
+    if (!strategy_support_carrier_migration(auip) || !auip->thr_spec)
+	auip->init.util.acul = 0;
+}
+
+static ERTS_INLINE void
+ensure_carrier_migration_support(struct au_init *auip)
+{
+    auip->thr_spec = 1; /* Need thread preferred */
+
+    /*
+     * If strategy cannot handle carrier migration,
+     * default to a strategy that can...
+     */
+    if (!strategy_support_carrier_migration(auip)) {
+	/* Default to aoffcaobf */
+	auip->atype = AOFIRSTFIT;
+	auip->init.aoff.bf_within_carrier = 1;
+    }
+}
+
 void
 erts_alloc_init(int *argc, char **argv, ErtsAllocInitOpts *eaiop)
 {
@@ -565,7 +625,6 @@ erts_alloc_init(int *argc, char **argv, ErtsAllocInitOpts *eaiop)
     hdbg_init();
 #endif
 
-    erts_have_sbmbc_alloc = 0;
     ncpu = eaiop->ncpu;
     if (ncpu < 1)
 	ncpu = 1;
@@ -575,7 +634,6 @@ erts_alloc_init(int *argc, char **argv, ErtsAllocInitOpts *eaiop)
     erts_sys_alloc_init();
     erts_init_utils_mem();
 
-    set_default_sbmbc_alloc_opts(&init.sbmbc_alloc);
     set_default_sl_alloc_opts(&init.sl_alloc);
     set_default_std_alloc_opts(&init.std_alloc);
     set_default_ll_alloc_opts(&init.ll_alloc);
@@ -591,7 +649,6 @@ erts_alloc_init(int *argc, char **argv, ErtsAllocInitOpts *eaiop)
 	handle_args(argc, argv, &init);
 
 #ifndef ERTS_SMP
-    init.sbmbc_alloc.thr_spec = 0;
     init.sl_alloc.thr_spec = 0;
     init.std_alloc.thr_spec = 0;
     init.ll_alloc.thr_spec = 0;
@@ -604,7 +661,6 @@ erts_alloc_init(int *argc, char **argv, ErtsAllocInitOpts *eaiop)
 
     if (init.erts_alloc_config) {
 	/* Adjust flags that erts_alloc_config won't like */
-	init.sbmbc_alloc.thr_spec = 0;
 	init.temp_alloc.thr_spec = 0;
 	init.sl_alloc.thr_spec = 0;
 	init.std_alloc.thr_spec = 0;
@@ -616,13 +672,22 @@ erts_alloc_init(int *argc, char **argv, ErtsAllocInitOpts *eaiop)
 	init.fix_alloc.thr_spec = 0;	
     }
 
+    check_disable_carrier_migration(&init.sl_alloc);
+    check_disable_carrier_migration(&init.std_alloc);
+    check_disable_carrier_migration(&init.ll_alloc);
+    check_disable_carrier_migration(&init.eheap_alloc);
+    check_disable_carrier_migration(&init.binary_alloc);
+    check_disable_carrier_migration(&init.ets_alloc);
+    check_disable_carrier_migration(&init.driver_alloc);
+    check_disable_carrier_migration(&init.fix_alloc);
+
+
 #ifdef ERTS_SMP
     /* Only temp_alloc can use thread specific interface */
     if (init.temp_alloc.thr_spec)
 	init.temp_alloc.thr_spec = erts_no_schedulers;
 
     /* Others must use thread preferred interface */
-    adjust_tpref(&init.sbmbc_alloc, erts_no_schedulers);
     adjust_tpref(&init.sl_alloc, erts_no_schedulers);
     adjust_tpref(&init.std_alloc, erts_no_schedulers);
     adjust_tpref(&init.ll_alloc, erts_no_schedulers);
@@ -641,7 +706,6 @@ erts_alloc_init(int *argc, char **argv, ErtsAllocInitOpts *eaiop)
      * The following allocators cannot be run with afit strategy.
      * Make sure they don't...
      */
-    refuse_af_strategy(&init.sbmbc_alloc);
     refuse_af_strategy(&init.sl_alloc);
     refuse_af_strategy(&init.std_alloc);
     refuse_af_strategy(&init.ll_alloc);
@@ -685,11 +749,6 @@ erts_alloc_init(int *argc, char **argv, ErtsAllocInitOpts *eaiop)
 
 #if HALFWORD_HEAP
     /* Init low memory variants by cloning */
-    init.sbmbc_low_alloc = init.sbmbc_alloc;
-    init.sbmbc_low_alloc.init.util.name_prefix = "sbmbc_low_";
-    init.sbmbc_low_alloc.init.util.alloc_no = ERTS_ALC_A_SBMBC_LOW;
-    init.sbmbc_low_alloc.init.util.low_mem = 1;
-
     init.std_low_alloc = init.std_alloc;
     init.std_low_alloc.init.util.name_prefix	= "std_low_";
     init.std_low_alloc.init.util.alloc_no = ERTS_ALC_A_STANDARD_LOW;
@@ -702,13 +761,11 @@ erts_alloc_init(int *argc, char **argv, ErtsAllocInitOpts *eaiop)
     init.ll_low_alloc.init.util.force = 1;
     init.ll_low_alloc.init.util.low_mem = 1;
 
-    set_au_allocator(ERTS_ALC_A_SBMBC_LOW, &init.sbmbc_low_alloc, ncpu);
     set_au_allocator(ERTS_ALC_A_STANDARD_LOW, &init.std_low_alloc, ncpu);
     set_au_allocator(ERTS_ALC_A_LONG_LIVED_LOW, &init.ll_low_alloc, ncpu);
 #endif /* HALFWORD */
 
     set_au_allocator(ERTS_ALC_A_TEMPORARY, &init.temp_alloc, ncpu);
-    set_au_allocator(ERTS_ALC_A_SBMBC, &init.sbmbc_alloc, ncpu);
     set_au_allocator(ERTS_ALC_A_SHORT_LIVED, &init.sl_alloc, ncpu);
     set_au_allocator(ERTS_ALC_A_STANDARD, &init.std_alloc, ncpu);
     set_au_allocator(ERTS_ALC_A_LONG_LIVED, &init.ll_alloc, ncpu);
@@ -735,20 +792,6 @@ erts_alloc_init(int *argc, char **argv, ErtsAllocInitOpts *eaiop)
 
     erts_mtrace_init(init.instr.mtrace, init.instr.nodename);
 
-    /* sbmbc_alloc() needs to be started first */
-    start_au_allocator(ERTS_ALC_A_SBMBC,
-		       &init.sbmbc_alloc,
-		       &sbmbc_alloc_state);
-#if HALFWORD_HEAP
-    start_au_allocator(ERTS_ALC_A_SBMBC_LOW,
-		       &init.sbmbc_low_alloc,
-		       &sbmbc_low_alloc_state);
-    erts_have_sbmbc_alloc = (init.sbmbc_alloc.enable
-			     && init.sbmbc_low_alloc.enable);
-#else
-    erts_have_sbmbc_alloc = init.sbmbc_alloc.enable;
-#endif
-
     start_au_allocator(ERTS_ALC_A_TEMPORARY,
 		       &init.temp_alloc,
 		       &temp_alloc_state);
@@ -1138,6 +1181,7 @@ get_kb_value(char *param_end, char** argv, int* ip)
 	return ((Uint) tmp)*1024;
 }
 
+#if 0
 static Uint
 get_byte_value(char *param_end, char** argv, int* ip)
 {
@@ -1151,6 +1195,7 @@ get_byte_value(char *param_end, char** argv, int* ip)
 	bad_value(param, param_end, value);
     return (Uint) tmp;
 }
+#endif
 
 static Uint
 get_amount_value(char *param_end, char** argv, int* ip)
@@ -1166,17 +1211,59 @@ get_amount_value(char *param_end, char** argv, int* ip)
     return (Uint) tmp;
 }
 
+static Uint
+get_acul_value(struct au_init *auip, char *param_end, char** argv, int* ip)
+{
+    Sint tmp;
+    char *rest;
+    char *param = argv[*ip]+1;
+    char *value = get_value(param_end, argv, ip);
+    if (sys_strcmp(value, "de") == 0) {
+	switch (auip->init.util.alloc_no) {
+	case ERTS_ALC_A_LONG_LIVED:
+#if HALFWORD_HEAP
+	case ERTS_ALC_A_LONG_LIVED_LOW:
+#endif
+	    return ERTS_ALC_DEFAULT_ENABLED_ACUL_LL_ALLOC;
+	case ERTS_ALC_A_EHEAP:
+	    return ERTS_ALC_DEFAULT_ENABLED_ACUL_EHEAP_ALLOC;
+	default:
+	    return ERTS_ALC_DEFAULT_ENABLED_ACUL;
+	}
+    }
+    errno = 0;
+    tmp = (Sint) ErtsStrToSint(value, &rest, 10);
+    if (errno != 0 || rest == value || tmp < 0 || 100 < tmp)
+	bad_value(param, param_end, value);
+    return (Uint) tmp;
+}
+
 static void
 handle_au_arg(struct au_init *auip,
 	      char* sub_param,
 	      char** argv,
-	      int* ip)
+	      int* ip,
+	      int u_switch)
 {
     char *param = argv[*ip]+1;
 
     switch (sub_param[0]) {
     case 'a':
-	if(has_prefix("asbcst", sub_param)) {
+	if (has_prefix("acul", sub_param)) {
+	    if (!auip->carrier_migration_allowed) {
+		if (!u_switch)
+		    goto bad_switch;
+		else {
+		    /* ignore */
+		    (void) get_acul_value(auip, sub_param + 4, argv, ip);
+		    break;
+		}
+	    }
+	    ensure_carrier_migration_support(auip);
+
+	    auip->init.util.acul = get_acul_value(auip, sub_param + 4, argv, ip);
+	}
+	else if(has_prefix("asbcst", sub_param)) {
 	    auip->init.util.asbcst = get_kb_value(sub_param + 6, argv, ip);
 	}
 	else if(has_prefix("as", sub_param)) {
@@ -1197,21 +1284,22 @@ handle_au_arg(struct au_init *auip,
 	    }
 	    else if (strcmp("aoff", alg) == 0) {
 		auip->atype = AOFIRSTFIT;
+		auip->init.aoff.bf_within_carrier = 0;
+	    }
+	    else if (strcmp("aoffcaobf", alg) == 0) {
+		auip->atype = AOFIRSTFIT;
+		auip->init.aoff.bf_within_carrier = 1;
 	    }
 	    else {
 		bad_value(param, sub_param + 1, alg);
 	    }
+	    check_disable_carrier_migration(auip);
 	}
 	else
 	    goto bad_switch;
 	break;
     case 'e':
 	auip->enable = get_bool_value(sub_param+1, argv, ip);
-#if !HAVE_ERTS_SBMBC
-	if (auip->init.util.alloc_no == ERTS_ALC_A_SBMBC) {
-	    auip->enable = 0;
-	}
-#endif
 	break;
     case 'l':
 	if (has_prefix("lmbcs", sub_param)) {
@@ -1271,18 +1359,6 @@ handle_au_arg(struct au_init *auip,
 	if(has_prefix("sbct", sub_param)) {
 	    auip->init.util.sbct = get_kb_value(sub_param + 4, argv, ip);
 	}
-	else if (has_prefix("sbmbcs", sub_param)) {
-#if HAVE_ERTS_SBMBC
-	    auip->init.util.sbmbcs =
-#endif
-		get_byte_value(sub_param + 6, argv, ip);
-	}
-	else if (has_prefix("sbmbct", sub_param)) {
-#if HAVE_ERTS_SBMBC
-	    auip->init.util.sbmbct =
-#endif
-		get_byte_value(sub_param + 6, argv, ip);
-	}
 	else if (has_prefix("smbcs", sub_param)) {
 	    auip->default_.smbcs = 0;
 	    auip->init.util.smbcs = get_kb_value(sub_param + 5, argv, ip);
@@ -1298,6 +1374,7 @@ handle_au_arg(struct au_init *auip,
 	}
 	else if (res == 0) {
 	    auip->thr_spec = 0;
+	    check_disable_carrier_migration(auip);
 	    break;
 	}
 	goto bad_switch;
@@ -1312,7 +1389,6 @@ static void
 handle_args(int *argc, char **argv, erts_alc_hndl_args_init_t *init)
 {
     struct au_init *aui[] = {
-	&init->sbmbc_alloc,
 	&init->binary_alloc,
 	&init->std_alloc,
 	&init->ets_alloc,
@@ -1339,25 +1415,22 @@ handle_args(int *argc, char **argv, erts_alc_hndl_args_init_t *init)
 	    case 'M':
 		switch (argv[i][2]) {
 		case 'B':
-		    handle_au_arg(&init->binary_alloc, &argv[i][3], argv, &i);
-		    break;
-		case 'C':
-		    handle_au_arg(&init->sbmbc_alloc, &argv[i][3], argv, &i);
+		    handle_au_arg(&init->binary_alloc, &argv[i][3], argv, &i, 0);
 		    break;
 		case 'D':
-		    handle_au_arg(&init->std_alloc, &argv[i][3], argv, &i);
+		    handle_au_arg(&init->std_alloc, &argv[i][3], argv, &i, 0);
 		    break;
 		case 'E':
-		    handle_au_arg(&init->ets_alloc, &argv[i][3], argv, &i);
+		    handle_au_arg(&init->ets_alloc, &argv[i][3], argv, &i, 0);
 		    break;
 		case 'F':
-		    handle_au_arg(&init->fix_alloc, &argv[i][3], argv, &i);
+		    handle_au_arg(&init->fix_alloc, &argv[i][3], argv, &i, 0);
 		    break;
 		case 'H':
-		    handle_au_arg(&init->eheap_alloc, &argv[i][3], argv, &i);
+		    handle_au_arg(&init->eheap_alloc, &argv[i][3], argv, &i, 0);
 		    break;
 		case 'L':
-		    handle_au_arg(&init->ll_alloc, &argv[i][3], argv, &i);
+		    handle_au_arg(&init->ll_alloc, &argv[i][3], argv, &i, 0);
 		    break;
 		case 'M':
 		    if (has_prefix("amcbf", argv[i]+3)) {
@@ -1383,13 +1456,13 @@ handle_args(int *argc, char **argv, erts_alc_hndl_args_init_t *init)
 		    }
 		    break;
 		case 'R':
-		    handle_au_arg(&init->driver_alloc, &argv[i][3], argv, &i);
+		    handle_au_arg(&init->driver_alloc, &argv[i][3], argv, &i, 0);
 		    break;
 		case 'S':
-		    handle_au_arg(&init->sl_alloc, &argv[i][3], argv, &i);
+		    handle_au_arg(&init->sl_alloc, &argv[i][3], argv, &i, 0);
 		    break;
 		case 'T':
-		    handle_au_arg(&init->temp_alloc, &argv[i][3], argv, &i);
+		    handle_au_arg(&init->temp_alloc, &argv[i][3], argv, &i, 0);
 		    break;
 		case 'Y': { /* sys_alloc */
 		    if (has_prefix("tt", param+2)) {
@@ -1448,9 +1521,6 @@ handle_args(int *argc, char **argv, erts_alc_hndl_args_init_t *init)
 			else if (strcmp("max", arg) == 0) {
 			    for (a = 0; a < aui_sz; a++)
 				aui[a]->enable = 1;
-#if !HAVE_ERTS_SBMBC
-			    init->sbmbc_alloc.enable = 0;
-#endif
 			}
 			else if (strcmp("config", arg) == 0) {
 			    init->erts_alloc_config = 1;
@@ -1478,6 +1548,7 @@ handle_args(int *argc, char **argv, erts_alc_hndl_args_init_t *init)
 
 			    for (a = 0; a < aui_sz; a++) {
 				aui[a]->thr_spec = 0;
+				check_disable_carrier_migration(aui[a]);
 				aui[a]->init.util.ramv = 0;
 				aui[a]->init.util.mmmbc = 10;
 				aui[a]->init.util.lmbcs = 5*1024*1024;
@@ -1542,7 +1613,7 @@ handle_args(int *argc, char **argv, erts_alc_hndl_args_init_t *init)
 				    argv[start + 1] = val;
 				i = start;
 			    }
-			    handle_au_arg(aui[a], &argv[i][3], argv, &i);
+			    handle_au_arg(aui[a], &argv[i][3], argv, &i, 1);
 			}
 		    }
 		    break;
@@ -2088,15 +2159,11 @@ erts_memory(int *print_to_p, void *print_to_arg, void *proc, Eterm earg)
 	    return am_badarg;
     }
 
-    /* All alloc_util allocators except sbmbc_alloc *have* to be enabled */
+    /* All alloc_util allocators *have* to be enabled */
     
     for (ai = ERTS_ALC_A_MIN; ai <= ERTS_ALC_A_MAX; ai++) {
 	switch (ai) {
 	case ERTS_ALC_A_SYSTEM:
-	case ERTS_ALC_A_SBMBC:
-#if HALFWORD_HEAP
-	case ERTS_ALC_A_SBMBC_LOW:
-#endif
 	    break;
 	default:
 	    if (!erts_allctrs_info[ai].enabled
@@ -2136,12 +2203,6 @@ erts_memory(int *print_to_p, void *print_to_arg, void *proc, Eterm earg)
 		      * Often not thread safe and usually never
 		      * contain any allocated memory.
 		      */
-		case ERTS_ALC_A_SBMBC:
-		    /* Included in other allocators */
-#if HALFWORD_HEAP
-		case ERTS_ALC_A_SBMBC_LOW:
-		    /* Included in other allocators */
-#endif
 		    continue;
 		case ERTS_ALC_A_EHEAP:
 		    save = &size.processes;
@@ -2585,7 +2646,7 @@ erts_allocator_info(int to, void *arg)
 			as = erts_allctr_thr_spec[a].allctr[ai];
 		    }
 		    /* Binary alloc has its own thread safety... */
-		    erts_alcu_info(as, 0, &to, arg, NULL, NULL);
+		    erts_alcu_info(as, 0, 0, &to, arg, NULL, NULL);
 		}
 		else {
 		    switch (a) {
@@ -2847,6 +2908,7 @@ reply_alloc_info(void *vair)
     int i;
     Eterm (*info_func)(Allctr_t *,
 		       int,
+		       int,
 		       int *,
 		       void *,
 		       Uint **,
@@ -2975,8 +3037,8 @@ reply_alloc_info(void *vair)
 			    allctr = erts_allctr_thr_spec[ai].allctr[0];
 			else
 			    allctr = erts_allctrs_info[ai].extra;
-			ainfo = info_func(allctr, hpp != NULL, NULL,
-					  NULL, hpp, szp);
+			ainfo = info_func(allctr, air->internal, hpp != NULL,
+					  NULL, NULL, hpp, szp);
 			ainfo = erts_bld_tuple(hpp, szp, 3, alloc_atom,
 					       make_small(0), ainfo);
 		    }
@@ -3011,7 +3073,7 @@ reply_alloc_info(void *vair)
 		    alloc_atom = erts_bld_atom(hpp, szp,
 					       (char *) ERTS_ALC_A2AD(ai));
 		    allctr = erts_allctr_thr_spec[ai].allctr[sched_id];
-		    ainfo = info_func(allctr, hpp != NULL, NULL,
+		    ainfo = info_func(allctr, air->internal, hpp != NULL, NULL,
 				      NULL, hpp, szp);
 		    ai_list = erts_bld_cons(hpp, szp,
 					    erts_bld_tuple(
@@ -3067,7 +3129,8 @@ int
 erts_request_alloc_info(struct process *c_p,
 			Eterm ref,
 			Eterm allocs,
-			int only_sz)
+			int only_sz,
+			int internal)
 {
     ErtsAllocInfoReq *air = aireq_alloc();
     Eterm req_ai[ERTS_ALC_A_MAX+1+2] = {0};
@@ -3079,6 +3142,8 @@ erts_request_alloc_info(struct process *c_p,
 
     air->only_sz = only_sz;
 
+    air->internal = internal;
+
     air->proc = c_p;
 
     if (is_not_internal_ref(ref))
@@ -3273,14 +3338,13 @@ UWord erts_alc_test(UWord op, UWord a1, UWord a2, UWord a3)
 	    init.atype = GOODFIT;
 	    init.init.util.name_prefix = (char *) a1;
 	    init.init.util.ts = a2 ? 1 : 0;
-	    init.init.util.sbmbct = 0;
 
 	    if ((char **) a3) {
 		char **argv = (char **) a3;
 		int i = 0;
 		while (argv[i]) {
 		    if (argv[i][0] == '-' && argv[i][1] == 't')
-			handle_au_arg(&init, &argv[i][2], argv, &i);
+			handle_au_arg(&init, &argv[i][2], argv, &i, 0);
 		    else
 			return (UWord) NULL;
 		    i++;
@@ -3400,6 +3464,11 @@ UWord erts_alc_test(UWord op, UWord a1, UWord a2, UWord a3)
 	    ERTS_ALC_TEST_ABORT;
 	    break;
 #endif /* #ifdef USE_THREADS */
+#ifdef ERTS_SMP
+	case 0xf13: return (UWord) 1;
+#else
+	case 0xf13: return (UWord) 0;
+#endif
 	default:
 	    break;
 	}
diff --git a/erts/emulator/beam/erl_alloc.h b/erts/emulator/beam/erl_alloc.h
index 9cafd8ddc8..d9fdfc6f58 100644
--- a/erts/emulator/beam/erl_alloc.h
+++ b/erts/emulator/beam/erl_alloc.h
@@ -65,7 +65,7 @@ Eterm erts_allocator_options(void *proc);
 struct process;
 
 int erts_request_alloc_info(struct process *c_p, Eterm ref, Eterm allocs,
-			    int only_sz);
+			    int only_sz, int internal);
 
 #define ERTS_ALLOC_INIT_DEF_OPTS_INITER {0}
 typedef struct {
@@ -100,14 +100,6 @@ UWord erts_alc_test(UWord,
 
 #define ERTS_ALC_MIN_LONG_LIVED_TIME	(10*60*1000)
 
-#if HALFWORD_HEAP
-#define ERTS_IS_SBMBC_ALLOCATOR_NO__(NO) \
-  ((NO) == ERTS_ALC_A_SBMBC || (NO) == ERTS_ALC_A_SBMBC_LOW)
-#else
-#define ERTS_IS_SBMBC_ALLOCATOR_NO__(NO) \
-  ((NO) == ERTS_ALC_A_SBMBC)
-#endif
-
 typedef struct {
     int alloc_util;
     int enabled;
diff --git a/erts/emulator/beam/erl_alloc.types b/erts/emulator/beam/erl_alloc.types
index f913525726..095ad24387 100644
--- a/erts/emulator/beam/erl_alloc.types
+++ b/erts/emulator/beam/erl_alloc.types
@@ -76,11 +76,6 @@
 
 allocator	SYSTEM		true		sys_alloc
 
-allocator	SBMBC		true		sbmbc_alloc
-+if halfword
-allocator	SBMBC_LOW	true		sbmbc_low_alloc
-+endif
-
 +if smp
 
 allocator	TEMPORARY	true		temp_alloc
@@ -146,7 +141,6 @@ class	SYSTEM		system_data
 #
 #	<TYPE>		<ALLOCATOR>	<CLASS>		<DESCRIPTION>
 
-type	SBMBC		SBMBC		SYSTEM		small_block_mbc
 type	PROC		FIXED_SIZE	PROCESSES	proc
 type	PORT		DRIVER		SYSTEM		port
 type	ATOM		LONG_LIVED	ATOM		atom_entry
@@ -351,7 +345,6 @@ type	SSB		SHORT_LIVED	PROCESSES	ssb
 
 +if halfword
 
-type	SBMBC_LOW	SBMBC_LOW	SYSTEM		small_block_mbc_low
 type	DDLL_PROCESS	STANDARD_LOW	SYSTEM		ddll_processes
 type	MONITOR_LH	STANDARD_LOW	PROCESSES	monitor_lh
 type	NLINK_LH	STANDARD_LOW	PROCESSES	nlink_lh
diff --git a/erts/emulator/beam/erl_alloc_util.c b/erts/emulator/beam/erl_alloc_util.c
index 53062979a6..b19e603a5f 100644
--- a/erts/emulator/beam/erl_alloc_util.c
+++ b/erts/emulator/beam/erl_alloc_util.c
@@ -71,21 +71,16 @@
 
 #define ALLOC_ZERO_EQ_NULL 0
 
+#ifndef ERTS_MSEG_FLG_2POW
+#  define ERTS_MSEG_FLG_2POW 0
+#endif
+#ifndef ERTS_MSEG_FLG_NONE
+#  define ERTS_MSEG_FLG_NONE 0
+#endif
+
 static int atoms_initialized = 0;
 static int initialized = 0;
 
-int erts_have_sbmbc_alloc;
-
-#if HAVE_ERTS_MSEG
-
-#define MSEG_UNIT_SHIFT         MSEG_ALIGN_BITS
-#define MSEG_UNIT_SZ            (1 << MSEG_UNIT_SHIFT)
-#define MSEG_UNIT_MASK		((~(UWord)0) << MSEG_UNIT_SHIFT)
-
-#define MSEG_UNIT_FLOOR(X)	((X) & MSEG_UNIT_MASK)
-#define MSEG_UNIT_CEILING(X)	MSEG_UNIT_FLOOR((X) + ~MSEG_UNIT_MASK)
-
-#endif
 
 #define INV_SYS_ALLOC_CARRIER_MASK	((UWord) (sys_alloc_carrier_size - 1))
 #define SYS_ALLOC_CARRIER_MASK		(~INV_SYS_ALLOC_CARRIER_MASK)
@@ -110,13 +105,12 @@ static Uint max_mseg_carriers;
 
 #define ONE_GIGA (1000000000)
 
-#define INC_CC(CC) ((CC).no == ONE_GIGA - 1				\
-		    ? ((CC).giga_no++, (CC).no = 0)			\
-		    : (CC).no++)
+#define ERTS_ALC_CC_GIGA_VAL(CC) ((CC) / ONE_GIGA)
+#define ERTS_ALC_CC_VAL(CC) ((CC) % ONE_GIGA)
+
+#define INC_CC(CC) ((CC)++)
 
-#define DEC_CC(CC) ((CC).no == 0					\
-		    ? ((CC).giga_no--, (CC).no = ONE_GIGA - 1)		\
-		    : (CC).no--)
+#define DEC_CC(CC) ((CC)--)
 
 /* Multi block carrier (MBC) memory layout in R16: 
 
@@ -173,14 +167,6 @@ MBC after deallocating first block:
 #define SET_BLK_SZ_FTR(B, SZ) \
   (((FreeBlkFtr_t *) (((char *) (B)) + (SZ)))[-1] = (SZ))
 
-#define THIS_FREE_BLK_HDR_FLG 	(((UWord) 1) << 0)
-#define PREV_FREE_BLK_HDR_FLG 	(((UWord) 1) << 1)
-#define LAST_BLK_HDR_FLG 	(((UWord) 1) << 2)
-
-/* Special flag combo for (allocated) SBC blocks 
-*/
-#define SBC_BLK_HDR_FLG (THIS_FREE_BLK_HDR_FLG | PREV_FREE_BLK_HDR_FLG | LAST_BLK_HDR_FLG)
-
 #define SET_MBC_ABLK_SZ(B, SZ) \
   (ASSERT(((SZ) & FLG_MASK) == 0), \
    (B)->bhdr = (((B)->bhdr) & ~MBC_ABLK_SZ_MASK) | (SZ))
@@ -222,18 +208,7 @@ MBC after deallocating first block:
      ASSERT(((UWord)(F) & (~FLG_MASK|THIS_FREE_BLK_HDR_FLG|PREV_FREE_BLK_HDR_FLG)) == THIS_FREE_BLK_HDR_FLG), \
      (B)->bhdr = ((Sz) | (F)), \
      (B)->u.carrier = (C))
-
-#  define ABLK_TO_MBC(B) \
-    (ASSERT(IS_MBC_BLK(B) && IS_ALLOCED_BLK(B)), \
-     (Carrier_t*)((MSEG_UNIT_FLOOR((UWord)(B)) - \
-		  (((B)->bhdr >> MBC_ABLK_OFFSET_SHIFT) << MSEG_UNIT_SHIFT))))
-
-#  define FBLK_TO_MBC(B) \
-    (ASSERT(IS_MBC_BLK(B) && IS_FREE_BLK(B)), \
-     (B)->u.carrier)
       
-#  define BLK_TO_MBC(B) (IS_FREE_BLK(B) ? FBLK_TO_MBC(B) : ABLK_TO_MBC(B))
-
 #  define IS_MBC_FIRST_ABLK(AP,B) \
   ((((UWord)(B) & ~MSEG_UNIT_MASK) == MBC_HEADER_SIZE(AP)) \
    && ((B)->bhdr & MBC_ABLK_OFFSET_MASK) == 0)
@@ -272,10 +247,6 @@ MBC after deallocating first block:
      (B)->bhdr = ((Sz) | (F)), \
      (B)->carrier = (C))
 
-#  define BLK_TO_MBC(B) ((B)->carrier)
-#  define ABLK_TO_MBC(B) BLK_TO_MBC(B)
-#  define FBLK_TO_MBC(B) BLK_TO_MBC(B)
-
 #  define IS_MBC_FIRST_BLK(AP,B) \
   ((char*)(B) == (char*)((B)->carrier) + MBC_HEADER_SIZE(AP))
 #  define IS_MBC_FIRST_ABLK(AP,B) IS_MBC_FIRST_BLK(AP,B)
@@ -300,8 +271,6 @@ MBC after deallocating first block:
   ((B)->bhdr & PREV_FREE_BLK_HDR_FLG)
 #define IS_PREV_BLK_ALLOCED(B) \
   (!IS_PREV_BLK_FREE((B)))
-#define IS_FREE_BLK(B) \
-  (ASSERT(!IS_SBC_BLK(B)), (B)->bhdr & THIS_FREE_BLK_HDR_FLG)
 #define IS_ALLOCED_BLK(B) \
   (!IS_FREE_BLK((B)))  
 #define IS_LAST_BLK(B) \
@@ -318,13 +287,6 @@ MBC after deallocating first block:
 #define GET_BLK_HDR_FLGS(B) \
   ((B)->bhdr & FLG_MASK)
 
-#define IS_SBC_BLK(B) \
-    (((B)->bhdr & FLG_MASK) == SBC_BLK_HDR_FLG)
-#define IS_MBC_BLK(B) \
-  (!IS_SBC_BLK((B)))
-
-#define MBC_BLK_SZ(B) (IS_FREE_BLK(B) ? MBC_FBLK_SZ(B) : MBC_ABLK_SZ(B))
-
 #define NXT_BLK(B) \
   (ASSERT(IS_MBC_BLK(B)), \
    (Block_t *) (((char *) (B)) + MBC_BLK_SZ((B))))
@@ -338,9 +300,96 @@ MBC after deallocating first block:
 
 /* Carriers ... */
 
-#define SBC_HEADER_SIZE	   (UNIT_CEILING(sizeof(Carrier_t) + ABLK_HDR_SZ) \
-			    - ABLK_HDR_SZ)
-#define MBC_HEADER_SIZE(AP) SBC_HEADER_SIZE
+/* #define ERTS_ALC_CPOOL_DEBUG */
+
+#if defined(DEBUG) && !defined(ERTS_ALC_CPOOL_DEBUG)
+#  define ERTS_ALC_CPOOL_DEBUG
+#endif
+
+#ifndef ERTS_SMP
+#  undef ERTS_ALC_CPOOL_DEBUG
+#endif
+
+#ifdef ERTS_ALC_CPOOL_DEBUG
+#  define ERTS_ALC_CPOOL_ASSERT(A)				\
+    ((void) ((A)						\
+	     ? 1						\
+	     : (erts_alcu_assert_failed(#A,			\
+					(char *) __FILE__,	\
+					__LINE__,		\
+					(char *) __func__),	\
+		0)))
+#else
+#  define ERTS_ALC_CPOOL_ASSERT(A) ((void) 1)
+#endif
+
+#ifdef ERTS_SMP
+#define ERTS_ALC_IS_CPOOL_ENABLED(A)	((A)->cpool.util_limit)
+#else
+#define ERTS_ALC_IS_CPOOL_ENABLED(A)	(0)
+#endif
+
+#ifdef ERTS_SMP
+
+#define ERTS_ALC_CPOOL_MAX_DISABLE_ABANDON		1000
+#define ERTS_ALC_CPOOL_ALLOC_OP_INC			8
+#define ERTS_ALC_CPOOL_FREE_OP_DEC			10
+
+#define ERTS_ALC_CPOOL_ALLOC_OP(A)						\
+do {										\
+    if ((A)->cpool.disable_abandon < ERTS_ALC_CPOOL_MAX_DISABLE_ABANDON) { 	\
+	(A)->cpool.disable_abandon += ERTS_ALC_CPOOL_ALLOC_OP_INC;		\
+	if ((A)->cpool.disable_abandon > ERTS_ALC_CPOOL_MAX_DISABLE_ABANDON)	\
+	    (A)->cpool.disable_abandon = ERTS_ALC_CPOOL_MAX_DISABLE_ABANDON;	\
+    }										\
+} while (0)
+
+
+#if ERTS_ALC_CPOOL_ALLOC_OP_INC >= ERTS_ALC_CPOOL_FREE_OP_DEC
+#  error "Implementation assume ERTS_ALC_CPOOL_ALLOC_OP_INC < ERTS_ALC_CPOOL_FREE_OP_DEC"
+#endif
+
+#define ERTS_ALC_CPOOL_REALLOC_OP(A)						\
+do {										\
+    if ((A)->cpool.disable_abandon) {						\
+	(A)->cpool.disable_abandon -= (ERTS_ALC_CPOOL_FREE_OP_DEC		\
+				       - ERTS_ALC_CPOOL_ALLOC_OP_INC);		\
+	if ((A)->cpool.disable_abandon < 0)					\
+	    (A)->cpool.disable_abandon = 0;					\
+    }										\
+} while (0)
+
+#define ERTS_ALC_CPOOL_FREE_OP(A)						\
+do {										\
+    if ((A)->cpool.disable_abandon) {						\
+	(A)->cpool.disable_abandon -= ERTS_ALC_CPOOL_FREE_OP_DEC;		\
+	if ((A)->cpool.disable_abandon < 0)					\
+	    (A)->cpool.disable_abandon = 0;					\
+    }										\
+} while (0)
+
+#else
+#define ERTS_ALC_CPOOL_ALLOC_OP(A)
+#define ERTS_ALC_CPOOL_REALLOC_OP(A)
+#define ERTS_ALC_CPOOL_FREE_OP(A)
+#endif
+
+#define ERTS_CRR_ALCTR_FLG_IN_POOL	(((erts_aint_t) 1) << 0)
+#define ERTS_CRR_ALCTR_FLG_BUSY		(((erts_aint_t) 1) << 1)
+
+#ifdef ERTS_SMP
+#define SBC_HEADER_SIZE	   						\
+    (UNIT_CEILING(sizeof(Carrier_t)					\
+		  - sizeof(ErtsAlcCPoolData_t)				\
+		  + ABLK_HDR_SZ)					\
+     - ABLK_HDR_SZ)
+#else
+#define SBC_HEADER_SIZE	   						\
+    (UNIT_CEILING(sizeof(Carrier_t)					\
+		  + ABLK_HDR_SZ)					\
+     - ABLK_HDR_SZ)
+#endif
+#define MBC_HEADER_SIZE(AP) ((AP)->mbc_header_size)
 
 
 #define MSEG_CARRIER_HDR_FLAG		(((UWord) 1) << 0)
@@ -352,7 +401,8 @@ MBC after deallocating first block:
 #define SCH_SBC				SBC_CARRIER_HDR_FLAG
 
 #define SET_CARRIER_HDR(C, Sz, F, AP) \
-  (ASSERT(((Sz) & FLG_MASK) == 0), (C)->chdr = ((Sz) | (F)), (C)->allctr = (AP))
+  (ASSERT(((Sz) & FLG_MASK) == 0), (C)->chdr = ((Sz) | (F)), \
+   erts_smp_atomic_init_nob(&(C)->allctr, (erts_aint_t) (AP)))
 
 #define BLK_TO_SBC(B) \
   ((Carrier_t *) (((char *) (B)) - SBC_HEADER_SIZE))
@@ -385,6 +435,7 @@ MBC after deallocating first block:
 #define CFLG_FORCE_SYS_ALLOC			(1 << 3)
 #define CFLG_FORCE_SIZE				(1 << 4)
 #define CFLG_MAIN_CARRIER			(1 << 5)
+#define CFLG_NO_CPOOL				(1 << 6)
 
 #ifdef ERTS_ALLOC_UTIL_HARD_DEBUG
 static void check_blk_carrier(Allctr_t *, Block_t *);
@@ -412,11 +463,7 @@ static void check_blk_carrier(Allctr_t *, Block_t *);
     ASSERT(((AP)->mbcs.curr.norm.sys_alloc.no				\
 	    && (AP)->mbcs.curr.norm.sys_alloc.size)			\
 	   || (!(AP)->mbcs.curr.norm.sys_alloc.no			\
-	       && !(AP)->mbcs.curr.norm.sys_alloc.size));		\
-    ASSERT(((AP)->sbmbcs.curr.small_block.no				\
-	    && (AP)->sbmbcs.curr.small_block.size)			\
-	   || (!(AP)->sbmbcs.curr.small_block.no			\
-	       && !(AP)->sbmbcs.curr.small_block.size))
+	       && !(AP)->mbcs.curr.norm.sys_alloc.size));
 
 #else
 #define DEBUG_CHECK_CARRIER_NO_SZ(AP)
@@ -487,17 +534,6 @@ do {									\
 			       + (AP)->mbcs.curr.norm.sys_alloc.size)
 
 
-#define STAT_SBMBC_ALLOC(AP, CSZ)					\
-do {									\
-    (AP)->sbmbcs.curr.small_block.no++;					\
-    (AP)->sbmbcs.curr.small_block.size += (CSZ);			\
-    if ((AP)->sbmbcs.max.no < (AP)->sbmbcs.curr.small_block.no)		\
-	(AP)->sbmbcs.max.no = (AP)->sbmbcs.curr.small_block.no;		\
-    if ((AP)->sbmbcs.max.size < (AP)->sbmbcs.curr.small_block.size)	\
-	(AP)->sbmbcs.max.size = (AP)->sbmbcs.curr.small_block.size;	\
-    DEBUG_CHECK_CARRIER_NO_SZ((AP));					\
-} while (0)
-
 #define STAT_MSEG_MBC_ALLOC(AP, CSZ)					\
 do {									\
     (AP)->mbcs.curr.norm.mseg.no++;					\
@@ -514,13 +550,19 @@ do {									\
     DEBUG_CHECK_CARRIER_NO_SZ((AP));					\
 } while (0)
 
-#define STAT_SBMBC_FREE(AP, CSZ)					\
+#define STAT_MBC_CPOOL_FETCH(AP, CRR)					\
 do {									\
-    ASSERT((AP)->sbmbcs.curr.small_block.no > 0);			\
-    (AP)->sbmbcs.curr.small_block.no--;					\
-    ASSERT((AP)->sbmbcs.curr.small_block.size >= (CSZ));		\
-    (AP)->sbmbcs.curr.small_block.size -= (CSZ);			\
-    DEBUG_CHECK_CARRIER_NO_SZ((AP));					\
+    UWord csz__ = CARRIER_SZ((CRR));					\
+    if (IS_MSEG_CARRIER((CRR)))						\
+	STAT_MSEG_MBC_ALLOC((AP), csz__);				\
+    else								\
+	STAT_SYS_ALLOC_MBC_ALLOC((AP), csz__);				\
+    (AP)->mbcs.blocks.curr.no += (CRR)->cpool.blocks;			\
+    if ((AP)->mbcs.blocks.max.no < (AP)->mbcs.blocks.curr.no)		\
+	(AP)->mbcs.blocks.max.no = (AP)->mbcs.blocks.curr.no;		\
+    (AP)->mbcs.blocks.curr.size += (CRR)->cpool.blocks_size;		\
+    if ((AP)->mbcs.blocks.max.size < (AP)->mbcs.blocks.curr.size)	\
+	(AP)->mbcs.blocks.max.size = (AP)->mbcs.blocks.curr.size;	\
 } while (0)
 
 #define STAT_MSEG_MBC_FREE(AP, CSZ)					\
@@ -541,28 +583,88 @@ do {									\
     DEBUG_CHECK_CARRIER_NO_SZ((AP));					\
 } while (0)
 
-#define STAT_MBC_BLK_ALLOC(AP, BSZ, FLGS)	       			\
+#define STAT_MBC_CPOOL_INSERT(AP, CRR)					\
+do {									\
+    UWord csz__ = CARRIER_SZ((CRR));					\
+    if (IS_MSEG_CARRIER((CRR)))						\
+	STAT_MSEG_MBC_FREE((AP), csz__);				\
+    else								\
+	STAT_SYS_ALLOC_MBC_FREE((AP), csz__);				\
+    ERTS_ALC_CPOOL_ASSERT((AP)->mbcs.blocks.curr.no			\
+			  >= (CRR)->cpool.blocks);			\
+    (AP)->mbcs.blocks.curr.no -= (CRR)->cpool.blocks;			\
+    ERTS_ALC_CPOOL_ASSERT((AP)->mbcs.blocks.curr.size 			\
+			  >= (CRR)->cpool.blocks_size);			\
+    (AP)->mbcs.blocks.curr.size -= (CRR)->cpool.blocks_size;		\
+} while (0)
+
+#ifdef ERTS_SMP
+#define STAT_MBC_BLK_ALLOC_CRR(CRR, BSZ)				\
+do {									\
+    (CRR)->cpool.blocks++;						\
+    (CRR)->cpool.blocks_size += (BSZ);					\
+} while (0)
+#else
+#define STAT_MBC_BLK_ALLOC_CRR(CRR, BSZ) ((void) (CRR)) /* Get rid of warning */
+#endif
+
+#define STAT_MBC_BLK_ALLOC(AP, CRR, BSZ, FLGS)	       			\
 do {									\
-    CarriersStats_t *cstats__ = (((FLGS) & ERTS_ALCU_FLG_SBMBC)		\
-				 ? &(AP)->sbmbcs			\
-				 : &(AP)->mbcs);			\
+    CarriersStats_t *cstats__ = &(AP)->mbcs;			        \
     cstats__->blocks.curr.no++;						\
     if (cstats__->blocks.max.no < cstats__->blocks.curr.no)		\
 	cstats__->blocks.max.no = cstats__->blocks.curr.no;		\
     cstats__->blocks.curr.size += (BSZ);				\
     if (cstats__->blocks.max.size < cstats__->blocks.curr.size)		\
 	cstats__->blocks.max.size = cstats__->blocks.curr.size;		\
+    STAT_MBC_BLK_ALLOC_CRR((CRR), (BSZ));				\
 } while (0)
 
-#define STAT_MBC_BLK_FREE(AP, BSZ, FLGS)				\
+static ERTS_INLINE int
+stat_cpool_mbc_blk_free(Allctr_t *allctr,
+			Carrier_t *crr,
+			Carrier_t **busy_pcrr_pp,
+			UWord blksz)
+{
+#ifdef ERTS_SMP
+
+    ERTS_ALC_CPOOL_ASSERT(crr->cpool.blocks > 0);
+    crr->cpool.blocks--;
+    ERTS_ALC_CPOOL_ASSERT(crr->cpool.blocks_size >= blksz);
+    crr->cpool.blocks_size -= blksz;
+
+    if (!busy_pcrr_pp || !*busy_pcrr_pp)
+	return 0;
+
+    ERTS_ALC_CPOOL_ASSERT(crr == *busy_pcrr_pp);
+
+#ifdef ERTS_ALC_CPOOL_DEBUG
+    ERTS_ALC_CPOOL_ASSERT(
+	erts_atomic_dec_read_nob(&allctr->cpool.stat.no_blocks) >= 0);
+    ERTS_ALC_CPOOL_ASSERT(
+	erts_atomic_add_read_nob(&allctr->cpool.stat.blocks_size,
+				 -((erts_aint_t) blksz)) >= 0);
+#else
+    erts_atomic_dec_nob(&allctr->cpool.stat.no_blocks);
+    erts_atomic_add_nob(&allctr->cpool.stat.blocks_size,
+			-((erts_aint_t) blksz));
+#endif
+
+    return 1;
+#else
+    return 0;
+#endif
+}
+
+#define STAT_MBC_BLK_FREE(AP, CRR, BPCRRPP, BSZ, FLGS)			\
 do {									\
-    CarriersStats_t *cstats__ = (((FLGS) & ERTS_ALCU_FLG_SBMBC)		\
-				 ? &(AP)->sbmbcs			\
-				 : &(AP)->mbcs);			\
-    ASSERT(cstats__->blocks.curr.no > 0);				\
-    cstats__->blocks.curr.no--;						\
-    ASSERT(cstats__->blocks.curr.size >= (BSZ));			\
-    cstats__->blocks.curr.size -= (BSZ);				\
+    if (!stat_cpool_mbc_blk_free((AP), (CRR), (BPCRRPP), (BSZ))) {	\
+	CarriersStats_t *cstats__ = &(AP)->mbcs;			\
+	ASSERT(cstats__->blocks.curr.no > 0);				\
+	cstats__->blocks.curr.no--;					\
+	ASSERT(cstats__->blocks.curr.size >= (BSZ));			\
+	cstats__->blocks.curr.size -= (BSZ);				\
+    }									\
 } while (0)
 
 /* Debug stuff... */
@@ -613,13 +715,42 @@ do {									\
 #define ERTS_ALCU_DBG_CHK_THR_ACCESS(A)
 #endif
 
-
 static void make_name_atoms(Allctr_t *allctr);
 
 static Block_t *create_carrier(Allctr_t *, Uint, UWord);
-static void destroy_carrier(Allctr_t *, Block_t *);
-static void mbc_free(Allctr_t *allctr, void *p);
+static void destroy_carrier(Allctr_t *, Block_t *, Carrier_t **);
+static void mbc_free(Allctr_t *allctr, void *p, Carrier_t **busy_pcrr_pp);
+static void dealloc_block(Allctr_t *, void *, int);
+
+/* internal data... */
+
+#if 0
+
+static ERTS_INLINE void *
+internal_alloc(UWord size)
+{
+    void *res = erts_sys_alloc(0, NULL, size);
+    if (!res)
+	erts_alloc_enomem(ERTS_ALC_T_UNDEF, size);
+    return res;
+}
 
+static ERTS_INLINE void *
+internal_realloc(void *ptr, UWord size)
+{
+    void *res = erts_sys_realloc(0, NULL, ptr, size);
+    if (!res)
+	erts_alloc_enomem(ERTS_ALC_T_UNDEF, size);
+    return res;
+}
+
+static ERTS_INLINE void
+internal_free(void *ptr)
+{
+    erts_sys_free(0, NULL, ptr);
+}
+
+#endif
 
 /* mseg ... */
 
@@ -781,10 +912,35 @@ unlink_carrier(CarrierList_t *cl, Carrier_t *crr)
     }
 }
 
-static Block_t *create_sbmbc(Allctr_t *allctr, Uint umem_sz);
-static void destroy_sbmbc(Allctr_t *allctr, Block_t *blk);
-static Block_t *create_carrier(Allctr_t *, Uint, UWord);
-static void destroy_carrier(Allctr_t *, Block_t *);
+#ifdef ERTS_SMP
+
+static ERTS_INLINE void
+clear_busy_pool_carrier(Allctr_t *allctr, Carrier_t *crr)
+{
+    if (crr) {
+	erts_aint_t max_size;
+	erts_aint_t new_val;
+
+	max_size = (erts_aint_t) allctr->largest_fblk_in_mbc(allctr, crr);
+	erts_atomic_set_nob(&crr->cpool.max_size, max_size);
+
+	new_val = (((erts_aint_t) allctr)|ERTS_CRR_ALCTR_FLG_IN_POOL);
+
+#ifdef ERTS_ALC_CPOOL_DEBUG
+	{
+	    erts_aint_t old_val = new_val|ERTS_CRR_ALCTR_FLG_BUSY;
+
+	    ERTS_ALC_CPOOL_ASSERT(old_val
+				  == erts_smp_atomic_xchg_relb(&crr->allctr,
+							       new_val));
+	}
+#else
+	erts_smp_atomic_set_relb(&crr->allctr, new_val);
+#endif
+    }
+}
+
+#endif
 
 #if 0
 #define ERTS_DBG_CHK_FIX_LIST(A, FIX, IX, B)			\
@@ -806,13 +962,154 @@ chk_fix_list(Allctr_t *allctr, ErtsAlcFixList_t *fix, int ix, int before)
 #define ERTS_DBG_CHK_FIX_LIST(A, FIX, IX, B)
 #endif
 
-erts_aint32_t
-erts_alcu_fix_alloc_shrink(Allctr_t *allctr, erts_aint32_t flgs)
+static void *mbc_alloc(Allctr_t *allctr, Uint size);
+
+#ifdef ERTS_SMP
+typedef struct {
+    ErtsAllctrDDBlock_t ddblock__; /* must be first */
+    ErtsAlcType_t fix_type;
+} ErtsAllctrFixDDBlock_t;
+#endif
+
+static ERTS_INLINE void
+dealloc_fix_block(Allctr_t *allctr,
+		  ErtsAlcType_t type,
+		  void *ptr,
+		  int dec_cc_on_redirect)
+{
+#ifdef ERTS_SMP
+    /* May be redirected... */
+    ((ErtsAllctrFixDDBlock_t *) ptr)->fix_type = type;
+#endif
+    dealloc_block(allctr, ptr, dec_cc_on_redirect);
+}
+
+static ERTS_INLINE void
+sched_fix_shrink(Allctr_t *allctr, int on)
+{
+    if (on && !allctr->fix_shrink_scheduled) {
+	allctr->fix_shrink_scheduled = 1;
+	erts_set_aux_work_timeout(allctr->ix,
+				  (ERTS_SSI_AUX_WORK_FIX_ALLOC_LOWER_LIM
+				   | ERTS_SSI_AUX_WORK_FIX_ALLOC_DEALLOC),
+				  1);
+    }
+    else if (!on && allctr->fix_shrink_scheduled) {
+	allctr->fix_shrink_scheduled = 0;
+	erts_set_aux_work_timeout(allctr->ix,
+				  (ERTS_SSI_AUX_WORK_FIX_ALLOC_LOWER_LIM
+				   | ERTS_SSI_AUX_WORK_FIX_ALLOC_DEALLOC),
+				  0);
+    }
+}
+
+static ERTS_INLINE void
+fix_cpool_check_shrink(Allctr_t *allctr,
+		       ErtsAlcType_t type,
+		       ErtsAlcFixList_t *fix,
+		       Carrier_t **busy_pcrr_pp)
+{
+    if (fix->u.cpool.shrink_list > 0) {
+	if (fix->list_size == 0)
+	    fix->u.cpool.shrink_list = 0;
+	else {
+	    void *p;
+#ifdef ERTS_SMP
+	    if (busy_pcrr_pp) {
+		clear_busy_pool_carrier(allctr, *busy_pcrr_pp);
+		*busy_pcrr_pp = NULL;
+	    }
+#endif
+	    fix->u.cpool.shrink_list--;
+	    p = fix->list;
+	    fix->list = *((void **) p);
+	    fix->list_size--;
+	    if (fix->u.cpool.min_list_size > fix->list_size)
+		fix->u.cpool.min_list_size = fix->list_size;
+
+	    fix->u.cpool.allocated--;
+	    dealloc_fix_block(allctr, type, p, 0);
+	}
+    }
+}
+
+static ERTS_INLINE void *
+fix_cpool_alloc(Allctr_t *allctr, ErtsAlcType_t type, Uint size)
+{
+    void *res;
+    ErtsAlcFixList_t *fix;
+
+    ASSERT(ERTS_ALC_N_MIN_A_FIXED_SIZE <= type
+	   && type <= ERTS_ALC_N_MAX_A_FIXED_SIZE);
+
+    fix = &allctr->fix[type - ERTS_ALC_N_MIN_A_FIXED_SIZE];
+
+    res = fix->list;
+    if (res) {
+	fix->list = *((void **) res);
+	fix->list_size--;
+	if (fix->u.cpool.min_list_size > fix->list_size)
+	    fix->u.cpool.min_list_size = fix->list_size;
+	fix->u.cpool.used++;
+	fix_cpool_check_shrink(allctr, type, fix, NULL);
+	return res;
+    }
+    if (size < 2*sizeof(UWord))
+	size += sizeof(UWord);
+    if (size >= allctr->sbc_threshold) {
+	Block_t *blk;
+	blk = create_carrier(allctr, size, CFLG_SBC);
+	res = blk ? BLK2UMEM(blk) : NULL;
+    }
+    else
+	res = mbc_alloc(allctr, size);
+    if (res) {
+	fix->u.cpool.used++;
+	fix->u.cpool.allocated++;
+    }
+    return res;
+}
+
+static ERTS_INLINE void
+fix_cpool_free(Allctr_t *allctr,
+	       ErtsAlcType_t type,
+	       void *p,
+	       Carrier_t **busy_pcrr_pp)
+{
+    ErtsAlcFixList_t *fix;
+
+    ASSERT(ERTS_ALC_N_MIN_A_FIXED_SIZE <= type
+	   && type <= ERTS_ALC_N_MAX_A_FIXED_SIZE);
+
+    fix = &allctr->fix[type - ERTS_ALC_N_MIN_A_FIXED_SIZE];
+    
+    fix->u.cpool.used--;
+
+    if ((!busy_pcrr_pp || !*busy_pcrr_pp)
+	&& !fix->u.cpool.shrink_list
+	&& fix->list_size < ERTS_ALCU_FIX_MAX_LIST_SZ) {
+	*((void **) p) = fix->list;
+	fix->list = p;
+	fix->list_size++;
+	sched_fix_shrink(allctr, 1);
+    }
+    else {
+	Block_t *blk = UMEM2BLK(p);
+	if (IS_SBC_BLK(blk))
+	    destroy_carrier(allctr, blk, NULL);
+	else
+	    mbc_free(allctr, p, busy_pcrr_pp);
+	fix->u.cpool.allocated--;
+	fix_cpool_check_shrink(allctr, type, fix, busy_pcrr_pp);
+    }
+}
+
+static ERTS_INLINE erts_aint32_t
+fix_cpool_alloc_shrink(Allctr_t *allctr, erts_aint32_t flgs)
 {
     int all_empty = 1;
     erts_aint32_t res = 0;
     int ix, o;
-    ErtsAlcFixList_t *fix = allctr->fix;
     int flush = flgs == 0;
 
 #ifdef USE_THREADS
@@ -821,56 +1118,204 @@ erts_alcu_fix_alloc_shrink(Allctr_t *allctr, erts_aint32_t flgs)
 #endif
 
     for (ix = 0; ix < ERTS_ALC_NO_FIXED_SIZES; ix++) {
+	ErtsAlcFixList_t *fix = &allctr->fix[ix];
+	ErtsAlcType_t type;
 	ERTS_DBG_CHK_FIX_LIST(allctr, fix, ix, 1);
-	if (flgs & ERTS_SSI_AUX_WORK_FIX_ALLOC_LOWER_LIM) {
-	    fix[ix].limit = fix[ix].max_used;
-	    if (fix[ix].limit < fix[ix].used)
-		fix[ix].limit = fix[ix].used;
-	    fix[ix].max_used = fix[ix].used;
-	    ASSERT(fix[ix].limit >= 0);
-
-	}
-	if (flush) {
-	    fix[ix].limit = 0;
-	    fix[ix].max_used = fix[ix].used;
-	    ASSERT(fix[ix].limit >= 0);
+	if (flush)
+	    fix->u.cpool.shrink_list = fix->list_size;
+	else if (flgs & ERTS_SSI_AUX_WORK_FIX_ALLOC_LOWER_LIM) {
+	    fix->u.cpool.shrink_list = fix->u.cpool.min_list_size;
+	    fix->u.cpool.min_list_size = fix->list_size;
 	}
+	type = (ErtsAlcType_t) (ix + ERTS_ALC_N_MIN_A_FIXED_SIZE);
 	for (o = 0; o < ERTS_ALC_FIX_MAX_SHRINK_OPS || flush; o++) {
-	    Block_t *blk;
 	    void *ptr;
 
-	    if (!flush && fix[ix].limit >= fix[ix].allocated)
+	    if (fix->u.cpool.shrink_list == 0)
 		break;
-	    if (fix[ix].list_size == 0)
+	    if (fix->list_size == 0) {
+		fix->u.cpool.shrink_list = 0;
 		break;
-	    ptr = fix[ix].list;
-	    fix[ix].list = *((void **) ptr);
-	    fix[ix].list_size--;	    
+	    }
+	    ptr = fix->list;
+	    fix->list = *((void **) ptr);
+	    fix->list_size--;
+	    fix->u.cpool.shrink_list--;
+	    fix->u.cpool.allocated--;
+	    dealloc_fix_block(allctr, type, ptr, 0);
+	}
+	if (fix->u.cpool.min_list_size > fix->list_size)
+	    fix->u.cpool.min_list_size = fix->list_size;
+	if (fix->list_size != 0) {
+	    if (fix->u.cpool.shrink_list > 0)
+		res |= ERTS_SSI_AUX_WORK_FIX_ALLOC_DEALLOC;
+	    all_empty = 0;
+	}
+    }
+
+    if (all_empty)
+	sched_fix_shrink(allctr, 0);
+
+#ifdef USE_THREADS
+    if (allctr->thread_safe)
+	erts_mtx_unlock(&allctr->mutex);
+#endif
 
-	    blk = UMEM2BLK(ptr);
+    return res;
+}
 
+static ERTS_INLINE void *
+fix_nocpool_alloc(Allctr_t *allctr, ErtsAlcType_t type, Uint size)
+{
+    ErtsAlcFixList_t *fix;
+    void *res;
+
+    ASSERT(ERTS_ALC_N_MIN_A_FIXED_SIZE <= type
+	   && type <= ERTS_ALC_N_MAX_A_FIXED_SIZE);
+
+    fix = &allctr->fix[type - ERTS_ALC_N_MIN_A_FIXED_SIZE];
+
+    ERTS_DBG_CHK_FIX_LIST(allctr, fix, ix, 1);
+    fix->u.nocpool.used++;
+    res = fix->list;
+    if (res) {
+	fix->list_size--;
+	fix->list = *((void **) res);
+	if (fix->list && fix->u.nocpool.allocated > fix->u.nocpool.limit) {
+	    Block_t *blk;
+	    void *p = fix->list;
+	    fix->list = *((void **) p);
+	    fix->list_size--;
+	    blk = UMEM2BLK(p);
 	    if (IS_SBC_BLK(blk))
-		destroy_carrier(allctr, blk);
+		destroy_carrier(allctr, blk, NULL);
 	    else
-		mbc_free(allctr, ptr);
+		mbc_free(allctr, p, NULL);
+	    fix->u.nocpool.allocated--;
+	}
+	ERTS_DBG_CHK_FIX_LIST(allctr, fix, ix, 0);
+	return res;
+    }
+    if (size < 2*sizeof(UWord))
+	size += sizeof(UWord);
+    if (fix->u.nocpool.limit < fix->u.nocpool.used)
+	fix->u.nocpool.limit = fix->u.nocpool.used;
+    if (fix->u.nocpool.max_used < fix->u.nocpool.used)
+	fix->u.nocpool.max_used = fix->u.nocpool.used;
+    fix->u.nocpool.allocated++;
 
-	    fix[ix].allocated--;
+    if (size >= allctr->sbc_threshold) {
+	Block_t *blk;
+	blk = create_carrier(allctr, size, CFLG_SBC);
+	res = blk ? BLK2UMEM(blk) : NULL;
+    }
+    else
+	res = mbc_alloc(allctr, size);
+
+    if (!res) {
+	fix->u.nocpool.allocated--;
+	fix->u.nocpool.used--;
+    }
+    return res;
+}
+
+static ERTS_INLINE void
+fix_nocpool_free(Allctr_t *allctr,
+		 ErtsAlcType_t type,
+		 void *p)
+{
+    Block_t *blk;
+    ErtsAlcFixList_t *fix;
+
+    ASSERT(ERTS_ALC_N_MIN_A_FIXED_SIZE <= type
+	   && type <= ERTS_ALC_N_MAX_A_FIXED_SIZE);
+
+    fix = &allctr->fix[type - ERTS_ALC_N_MIN_A_FIXED_SIZE];
+
+    ERTS_DBG_CHK_FIX_LIST(allctr, fix, ix, 1);
+    fix->u.nocpool.used--;
+    if (fix->u.nocpool.allocated < fix->u.nocpool.limit
+	&& fix->list_size < ERTS_ALCU_FIX_MAX_LIST_SZ) {
+	*((void **) p) = fix->list;
+	fix->list = p;
+	fix->list_size++;
+	sched_fix_shrink(allctr, 1);
+	ERTS_DBG_CHK_FIX_LIST(allctr, fix, ix, 0);
+	return;
+    }
+    fix->u.nocpool.allocated--;
+    if (fix->list && fix->u.nocpool.allocated > fix->u.nocpool.limit) {
+	blk = UMEM2BLK(p);
+	if (IS_SBC_BLK(blk))
+	    destroy_carrier(allctr, blk, NULL);
+	else
+	    mbc_free(allctr, p, NULL);
+	p = fix->list;
+	fix->list = *((void **) p);
+	fix->list_size--;
+	fix->u.nocpool.allocated--;
+    }
+
+    blk = UMEM2BLK(p);
+    if (IS_SBC_BLK(blk))
+	destroy_carrier(allctr, blk, NULL);
+    else
+	mbc_free(allctr, p, NULL);
+    ERTS_DBG_CHK_FIX_LIST(allctr, fix, ix, 0);
+}
+
+static ERTS_INLINE erts_aint32_t
+fix_nocpool_alloc_shrink(Allctr_t *allctr, erts_aint32_t flgs)
+{
+    int all_empty = 1;
+    erts_aint32_t res = 0;
+    int ix, o;
+    int flush = flgs == 0;
+
+#ifdef USE_THREADS
+    if (allctr->thread_safe)
+	erts_mtx_lock(&allctr->mutex);
+#endif
+
+    for (ix = 0; ix < ERTS_ALC_NO_FIXED_SIZES; ix++) {
+	ErtsAlcFixList_t *fix = &allctr->fix[ix];
+	ERTS_DBG_CHK_FIX_LIST(allctr, fix, ix, 1);
+	if (flgs & ERTS_SSI_AUX_WORK_FIX_ALLOC_LOWER_LIM) {
+	    fix->u.nocpool.limit = fix->u.nocpool.max_used;
+	    if (fix->u.nocpool.limit < fix->u.nocpool.used)
+		fix->u.nocpool.limit = fix->u.nocpool.used;
+	    fix->u.nocpool.max_used = fix->u.nocpool.used;
+	    ASSERT(fix->u.nocpool.limit >= 0);
+
+	}
+	if (flush) {
+	    fix->u.nocpool.limit = 0;
+	    fix->u.nocpool.max_used = fix->u.nocpool.used;
+	    ASSERT(fix->u.nocpool.limit >= 0);
 	}
-	if (fix[ix].list_size != 0) {
-	    if (fix[ix].limit < fix[ix].allocated)
+	for (o = 0; o < ERTS_ALC_FIX_MAX_SHRINK_OPS || flush; o++) {
+	    void *ptr;
+
+	    if (!flush && fix->u.nocpool.limit >= fix->u.nocpool.allocated)
+		break;
+	    if (fix->list_size == 0)
+		break;
+	    ptr = fix->list;
+	    fix->list = *((void **) ptr);
+	    fix->list_size--;
+	    dealloc_block(allctr, ptr, 0);
+	    fix->u.nocpool.allocated--;
+	}
+	if (fix->list_size != 0) {
+	    if (fix->u.nocpool.limit < fix->u.nocpool.allocated)
 		res |= ERTS_SSI_AUX_WORK_FIX_ALLOC_DEALLOC;
 	    all_empty = 0;
 	}
 	ERTS_DBG_CHK_FIX_LIST(allctr, fix, ix, 0);
     }
 
-    if (all_empty && allctr->fix_shrink_scheduled) {
-	allctr->fix_shrink_scheduled = 0;
-	erts_set_aux_work_timeout(allctr->ix,
-				  (ERTS_SSI_AUX_WORK_FIX_ALLOC_LOWER_LIM
-				   | ERTS_SSI_AUX_WORK_FIX_ALLOC_DEALLOC),
-				  0);
-    }
+    if (all_empty)
+	sched_fix_shrink(allctr, 0);
 
 #ifdef USE_THREADS
     if (allctr->thread_safe)
@@ -880,13 +1325,18 @@ erts_alcu_fix_alloc_shrink(Allctr_t *allctr, erts_aint32_t flgs)
     return res;
 }
 
-#ifdef ERTS_SMP
+erts_aint32_t
+erts_alcu_fix_alloc_shrink(Allctr_t *allctr, erts_aint32_t flgs)
+{
+    if (ERTS_ALC_IS_CPOOL_ENABLED(allctr))
+	return fix_cpool_alloc_shrink(allctr, flgs);
+    else
+	return fix_nocpool_alloc_shrink(allctr, flgs);
+}
 
-typedef struct {
-    ErtsAllctrDDBlock_t ddblock__; /* must be first */
-    ErtsAlcType_t fix_type;
-}ErtsAllctrFixDDBlock_t;
+static void dealloc_carrier(Allctr_t *allctr, Carrier_t *crr, Uint mseg_flags);
 
+#ifdef ERTS_SMP
 
 static ERTS_INLINE Allctr_t*
 get_pref_allctr(void *extra)
@@ -902,6 +1352,9 @@ get_pref_allctr(void *extra)
     return tspec->allctr[pref_ix];
 }
 
+#define ERTS_ALC_TS_PREF_LOCK_IF_USED	(1)
+#define ERTS_ALC_TS_PREF_LOCK_NO	(0)
+
 /* SMP note:
  * get_used_allctr() must be safe WITHOUT locking the allocator while
  * concurrent threads may be updating adjacent blocks.
@@ -910,22 +1363,85 @@ get_pref_allctr(void *extra)
  * the "PREV_FREE" flag bit. 
  */
 static ERTS_INLINE Allctr_t*
-get_used_allctr(void *extra, void *p, UWord *sizep)
+get_used_allctr(Allctr_t *pref_allctr, int pref_lock, void *p, UWord *sizep,
+		Carrier_t **busy_pcrr_pp)
 {
     Block_t* blk = UMEM2BLK(p);
-    Carrier_t* crr;
+    Carrier_t *crr;
+    erts_aint_t iallctr;
+    Allctr_t *used_allctr;
+
+    *busy_pcrr_pp = NULL;
 
     if (IS_SBC_BLK(blk)) {
 	crr = BLK_TO_SBC(blk);
 	if (sizep)
 	    *sizep = SBC_BLK_SZ(blk) - ABLK_HDR_SZ;  
+	iallctr = erts_smp_atomic_read_dirty(&crr->allctr);
     }
     else {
 	crr = ABLK_TO_MBC(blk);
+
 	if (sizep)
 	    *sizep = MBC_ABLK_SZ(blk) - ABLK_HDR_SZ;
+	if (!ERTS_ALC_IS_CPOOL_ENABLED(pref_allctr))
+	    iallctr = erts_smp_atomic_read_dirty(&crr->allctr);
+	else {
+	    int locked_pref_allctr = 0;
+	    iallctr = erts_smp_atomic_read_ddrb(&crr->allctr);
+
+	    if (ERTS_ALC_TS_PREF_LOCK_IF_USED == pref_lock
+		&& pref_allctr->thread_safe) {
+		used_allctr = (Allctr_t *) (iallctr & ~FLG_MASK);
+		if (pref_allctr == used_allctr) {
+		    erts_mtx_lock(&pref_allctr->mutex);
+		    locked_pref_allctr = 1;
+		}
+	    }
+
+	    while ((iallctr & ((~FLG_MASK)|ERTS_CRR_ALCTR_FLG_IN_POOL))
+		   == (((erts_aint_t) pref_allctr)|ERTS_CRR_ALCTR_FLG_IN_POOL)) {
+		erts_aint_t act;
+
+		ERTS_ALC_CPOOL_ASSERT(!(iallctr & ERTS_CRR_ALCTR_FLG_BUSY));
+		act = erts_smp_atomic_cmpxchg_ddrb(&crr->allctr,
+						   iallctr|ERTS_CRR_ALCTR_FLG_BUSY,
+						   iallctr);
+		if (act == iallctr) {
+		    *busy_pcrr_pp = crr;
+		    break;
+		}
+		iallctr = act;
+	    }
+
+	    used_allctr = (Allctr_t *) (iallctr & ~FLG_MASK);
+
+	    if (ERTS_ALC_TS_PREF_LOCK_IF_USED == pref_lock) {
+		if (locked_pref_allctr && used_allctr != pref_allctr) {
+		    /* Was taken out of pool; now owned by someone else */
+		    erts_mtx_unlock(&pref_allctr->mutex);
+		}
+	    }
+
+	    ERTS_ALC_CPOOL_ASSERT(
+		(((iallctr & ~FLG_MASK) == (erts_aint_t) pref_allctr)
+		 ? (((iallctr & FLG_MASK) == ERTS_CRR_ALCTR_FLG_IN_POOL)
+		    || ((iallctr & FLG_MASK) == 0))
+		 : 1));
+
+	    return used_allctr;
+	}
+    }
+
+    used_allctr = (Allctr_t *) (iallctr & ~FLG_MASK);
+
+    if (ERTS_ALC_TS_PREF_LOCK_IF_USED == pref_lock
+	&& used_allctr == pref_allctr
+	&& pref_allctr->thread_safe) {
+	erts_mtx_lock(&pref_allctr->mutex);
     }
-    return crr->allctr;
+
+    return used_allctr;
 }
 
 static void
@@ -1020,7 +1536,7 @@ check_insert_marker(ErtsAllctrDDQueue_t *ddq, erts_aint_t ilast)
 }
 
 static ERTS_INLINE int
-ddq_enqueue(ErtsAlcType_t type, ErtsAllctrDDQueue_t *ddq, void *ptr, int cinit)
+ddq_enqueue(ErtsAllctrDDQueue_t *ddq, void *ptr, int cinit)
 {
     int last_elem;
     int um_refc_ix = 0;
@@ -1121,6 +1637,59 @@ store_earliest_thr_prgr(ErtsThrPrgrVal *prev_val, ErtsAllctrDDQueue_t *ddq)
     }
 }
 
+static void
+check_pending_dealloc_carrier(Allctr_t *allctr,
+			      int *need_thr_progress,
+			      ErtsThrPrgrVal *thr_prgr_p,
+			      int *need_more_work);
+
+static void
+handle_delayed_fix_dealloc(Allctr_t *allctr, void *ptr)
+{
+    ErtsAlcType_t type;
+
+    type = ((ErtsAllctrFixDDBlock_t *) ptr)->fix_type;
+
+    ASSERT(ERTS_ALC_N_MIN_A_FIXED_SIZE <= type
+	   && type <= ERTS_ALC_N_MAX_A_FIXED_SIZE);
+
+    if (!ERTS_ALC_IS_CPOOL_ENABLED(allctr))
+	fix_nocpool_free(allctr, type, ptr);
+    else {
+	Block_t *blk = UMEM2BLK(ptr);
+	Carrier_t *busy_pcrr_p;
+	Allctr_t *used_allctr;
+
+	if (IS_SBC_BLK(blk)) {
+	    busy_pcrr_p = NULL;
+	    goto doit;
+	}
+
+	used_allctr = get_used_allctr(allctr, ERTS_ALC_TS_PREF_LOCK_NO, ptr,
+				      NULL, &busy_pcrr_p);
+	if (used_allctr == allctr) {
+	doit:
+	    fix_cpool_free(allctr, type, ptr, &busy_pcrr_p);
+	    clear_busy_pool_carrier(allctr, busy_pcrr_p);
+	}
+	else {
+	    /* Carrier migrated; need to redirect block to new owner... */
+	    int cinit = used_allctr->dd.ix - allctr->dd.ix;
+
+	    ERTS_ALC_CPOOL_ASSERT(!busy_pcrr_p);
+
+	    DEC_CC(allctr->calls.this_free);
+
+	    ((ErtsAllctrFixDDBlock_t *) ptr)->fix_type = type;
+	    if (ddq_enqueue(&used_allctr->dd.q, ptr, cinit))
+		erts_alloc_notify_delayed_dealloc(used_allctr->ix);
+	}
+    }
+}
+
+static void
+schedule_dealloc_carrier(Allctr_t *allctr, Carrier_t *crr);
+
 static ERTS_INLINE int
 handle_delayed_dealloc(Allctr_t *allctr,
 		       int allctr_locked,
@@ -1152,7 +1721,6 @@ handle_delayed_dealloc(Allctr_t *allctr,
     while (1) {
 	Block_t *blk;
 	void *ptr;
-	int ix;
 
 	if (use_limit && ++ops > ops_limit) {
 	    if (ddq->head.first != ddq->head.unref_end) {
@@ -1181,52 +1749,29 @@ handle_delayed_dealloc(Allctr_t *allctr,
 
 	res = 1;
 
-	INC_CC(allctr->calls.this_free);
-
-	if (fix) {
-	    ErtsAlcType_t type;
-
-	    type = ((ErtsAllctrFixDDBlock_t*) ptr)->fix_type;
-	    ix = type - ERTS_ALC_N_MIN_A_FIXED_SIZE;
-	    ERTS_DBG_CHK_FIX_LIST(allctr, fix, ix, 1);
-	    fix[ix].used--;
-	    if (fix[ix].allocated < fix[ix].limit
-		&& fix[ix].list_size < ERTS_ALCU_FIX_MAX_LIST_SZ) {
-		*((void **) ptr) = fix[ix].list;
-		fix[ix].list = ptr;
-		fix[ix].list_size++;
-		if (!allctr->fix_shrink_scheduled) {
-		    allctr->fix_shrink_scheduled = 1;
-		    erts_set_aux_work_timeout(
-			allctr->ix,
-			(ERTS_SSI_AUX_WORK_FIX_ALLOC_LOWER_LIM
-			 | ERTS_SSI_AUX_WORK_FIX_ALLOC_DEALLOC),
-			1);
-		}
-		ERTS_DBG_CHK_FIX_LIST(allctr, fix, ix, 0);
-		continue;
-	    }
-	    fix[ix].allocated--;
-	    if (fix[ix].list && fix[ix].allocated > fix[ix].limit) {
-		blk = UMEM2BLK(ptr);
-		if (IS_SBC_BLK(blk))
-		    destroy_carrier(allctr, blk);
-		else
-		    mbc_free(allctr, ptr);
-		ptr = fix[ix].list;
-		fix[ix].list = *((void **) ptr);
-		fix[ix].list_size--;
-		fix[ix].allocated--;
-	    }
+	blk = UMEM2BLK(ptr);
+	if (IS_FREE_LAST_MBC_BLK(blk)) {
+	    /*
+	     * A multiblock carrier that previously has been migrated away
+	     * from us and now is back to be deallocated...
+	     *
+	     * Note that we cannot use FBLK_TO_MBC(blk) since it
+	     * data has been overwritten by the queue.
+	     */
+	    Carrier_t *crr = FIRST_BLK_TO_MBC(allctr, blk);
+	    ERTS_ALC_CPOOL_ASSERT(ERTS_ALC_IS_CPOOL_ENABLED(allctr));
+	    ERTS_ALC_CPOOL_ASSERT(allctr == crr->cpool.orig_allctr);
+	    schedule_dealloc_carrier(allctr, crr);
 	}
+	else {
 
-	blk = UMEM2BLK(ptr);
+	    INC_CC(allctr->calls.this_free);
 
-	if (IS_SBC_BLK(blk))
-	    destroy_carrier(allctr, blk);
-	else
-	    mbc_free(allctr, ptr);
-	ERTS_DBG_CHK_FIX_LIST(allctr, fix, ix, 0);
+	    if (fix)
+		handle_delayed_fix_dealloc(allctr, ptr);
+	    else
+		dealloc_block(allctr, ptr, 1);
+	}
     }
 
     if (need_thr_progress && !(need_thr_prgr | need_mr_wrk)) {
@@ -1236,6 +1781,12 @@ handle_delayed_dealloc(Allctr_t *allctr,
 	    store_earliest_thr_prgr(thr_prgr_p, ddq);
     }
 
+    if (ERTS_ALC_IS_CPOOL_ENABLED(allctr))
+	check_pending_dealloc_carrier(allctr,
+				      need_thr_progress,
+				      thr_prgr_p,
+				      need_more_work);
+
     if (allctr->thread_safe && !allctr_locked)
 	erts_mtx_unlock(&allctr->mutex);
    return res;
@@ -1250,13 +1801,59 @@ enqueue_dealloc_other_instance(ErtsAlcType_t type,
     if (allctr->fix)
 	((ErtsAllctrFixDDBlock_t*) ptr)->fix_type = type;
 
-    if (ddq_enqueue(type, &allctr->dd.q, ptr, cinit))
+    if (ddq_enqueue(&allctr->dd.q, ptr, cinit))
 	erts_alloc_notify_delayed_dealloc(allctr->ix);
 }
 
 #endif
 
 #ifdef ERTS_SMP
+static void
+set_new_allctr_abandon_limit(Allctr_t *allctr);
+static void
+abandon_carrier(Allctr_t *allctr, Carrier_t *crr);
+
+
+static ERTS_INLINE void
+check_abandon_carrier(Allctr_t *allctr, Block_t *fblk, Carrier_t **busy_pcrr_pp)
+{
+    Carrier_t *crr;
+
+    if (busy_pcrr_pp && *busy_pcrr_pp)
+	return;
+
+    if (!ERTS_ALC_IS_CPOOL_ENABLED(allctr))
+	return;
+
+    allctr->cpool.check_limit_count--;
+    if (--allctr->cpool.check_limit_count <= 0)
+	set_new_allctr_abandon_limit(allctr);
+
+    if (!erts_thr_progress_is_managed_thread())
+	return;
+
+    if (allctr->cpool.disable_abandon)
+	return;
+
+    if (allctr->mbcs.blocks.curr.size > allctr->cpool.abandon_limit)
+	return;
+
+
+    crr = FBLK_TO_MBC(fblk);
+
+    if (allctr->main_carrier == crr)
+	return;
+
+    if (crr->cpool.blocks_size > crr->cpool.abandon_limit)
+	return;
+
+    if (crr->cpool.thr_prgr != ERTS_THR_PRGR_INVALID
+	&& !erts_thr_progress_has_reached(crr->cpool.thr_prgr))
+	return;
+
+    abandon_carrier(allctr, crr);
+}
+
 void
 erts_alcu_check_delayed_dealloc(Allctr_t *allctr,
 				int limit,
@@ -1274,78 +1871,88 @@ erts_alcu_check_delayed_dealloc(Allctr_t *allctr,
 }
 #endif
 
-#define ERTS_ALCU_HANDLE_DD_IN_OP(Allctr, Locked) \
-    handle_delayed_dealloc((Allctr), (Locked), 1, \
+#define ERTS_ALCU_HANDLE_DD_IN_OP(Allctr, Locked)			\
+    handle_delayed_dealloc((Allctr), (Locked), 1, 			\
 			   ERTS_ALCU_DD_OPS_LIM_LOW, NULL, NULL, NULL)
 
+static void
+dealloc_block(Allctr_t *allctr, void *ptr, int dec_cc_on_redirect)
+{
+    Block_t *blk = UMEM2BLK(ptr);
+
+    ERTS_SMP_LC_ASSERT(!allctr->thread_safe
+		       || erts_lc_mtx_is_locked(&allctr->mutex));
+
+    if (IS_SBC_BLK(blk))
+	destroy_carrier(allctr, blk, NULL);
+#ifndef ERTS_SMP
+    else
+	mbc_free(allctr, ptr, NULL);
+#else
+    else if (!ERTS_ALC_IS_CPOOL_ENABLED(allctr))
+	mbc_free(allctr, ptr, NULL);
+    else {
+	Carrier_t *busy_pcrr_p;
+	Allctr_t *used_allctr;
+	used_allctr = get_used_allctr(allctr, ERTS_ALC_TS_PREF_LOCK_NO, ptr,
+				      NULL, &busy_pcrr_p);
+	if (used_allctr == allctr) {
+	    mbc_free(allctr, ptr, &busy_pcrr_p);
+	    clear_busy_pool_carrier(allctr, busy_pcrr_p);
+	}
+	else {
+	    /* Carrier migrated; need to redirect block to new owner... */
+	    int cinit = used_allctr->dd.ix - allctr->dd.ix;
+
+	    ERTS_ALC_CPOOL_ASSERT(!busy_pcrr_p);
+
+	    if (dec_cc_on_redirect)
+		DEC_CC(allctr->calls.this_free);
+	    if (ddq_enqueue(&used_allctr->dd.q, ptr, cinit))
+		erts_alloc_notify_delayed_dealloc(used_allctr->ix);
+	}
+    }
+#endif
+}
+
 /* Multi block carrier alloc/realloc/free ... */
 
 /* NOTE! mbc_alloc() may in case of memory shortage place the requested
  * block in a sbc.
  */
 static ERTS_INLINE void *
-mbc_alloc_block(Allctr_t *allctr, Uint size, Uint *blk_szp, Uint32 *alcu_flgsp)
+mbc_alloc_block(Allctr_t *allctr, Uint size, Uint *blk_szp)
 {
     Block_t *blk;
     Uint get_blk_sz;
-    Uint sbmbct;
 
     ASSERT(size);
     ASSERT(size < allctr->sbc_threshold);
 
     *blk_szp = get_blk_sz = UMEMSZ2BLKSZ(allctr, size);
 
-    sbmbct = allctr->sbmbc_threshold;
-    if (sbmbct) {
-	if (get_blk_sz < sbmbct) {
-	    *alcu_flgsp |= ERTS_ALCU_FLG_SBMBC;
-	    if (get_blk_sz + allctr->min_block_size > sbmbct) {
-		/* Since we use block size to determine if blocks are
-		   located in sbmbc or not... */
-		get_blk_sz += allctr->min_block_size;
-	    }
-	}
-    }
-
-#ifdef ERTS_SMP
-    if (allctr->dd.use)
-	ERTS_ALCU_HANDLE_DD_IN_OP(allctr, 1);
-#endif
-
-    blk = (*allctr->get_free_block)(allctr, get_blk_sz, NULL, 0, *alcu_flgsp);
-
-#ifdef ERTS_SMP
-    if (!blk && allctr->dd.use) {
-	if (ERTS_ALCU_HANDLE_DD_IN_OP(allctr, 1))
-	    blk = (*allctr->get_free_block)(allctr, get_blk_sz, NULL, 0,
-					    *alcu_flgsp);
-    }
-#endif
+    blk = (*allctr->get_free_block)(allctr, get_blk_sz, NULL, 0);
 
     if (!blk) {
-	if ((*alcu_flgsp) & ERTS_ALCU_FLG_SBMBC) 
-	    blk = create_sbmbc(allctr, get_blk_sz);
-	else {
-	    blk = create_carrier(allctr, get_blk_sz, CFLG_MBC);
+	blk = create_carrier(allctr, get_blk_sz, CFLG_MBC);
 #if !HALFWORD_HEAP && !HAVE_SUPER_ALIGNED_MB_CARRIERS
-	    if (!blk) {
-		/* Emergency! We couldn't create the carrier as we wanted.
-		   Try to place it in a sys_alloced sbc. */
-		blk = create_carrier(allctr,
-				     size,
-				     (CFLG_SBC
-				      | CFLG_FORCE_SIZE
-				      | CFLG_FORCE_SYS_ALLOC));
-	    }
-#endif
+	if (!blk) {
+	    /* Emergency! We couldn't create the carrier as we wanted.
+	       Try to place it in a sys_alloced sbc. */
+	    blk = create_carrier(allctr,
+				 size,
+				 (CFLG_SBC
+				  | CFLG_FORCE_SIZE
+				  | CFLG_FORCE_SYS_ALLOC));
 	}
+#endif
     }
 
 #ifdef ERTS_ALLOC_UTIL_HARD_DEBUG
     if (IS_MBC_BLK(blk)) {
-	(*allctr->link_free_block)(allctr, blk, *alcu_flgsp);
+	(*allctr->link_free_block)(allctr, blk);
 	HARD_CHECK_BLK_CARRIER(allctr, blk);
-	(*allctr->unlink_free_block)(allctr, blk, *alcu_flgsp);
+	(*allctr->unlink_free_block)(allctr, blk);
     }
 #endif
 
@@ -1359,8 +1966,7 @@ mbc_alloc_finalize(Allctr_t *allctr,
 		   UWord flags,
 		   Carrier_t *crr,
 		   Uint want_blk_sz,
-		   int valid_blk_info,
-		   Uint32 alcu_flgs)
+		   int valid_blk_info)
 {
     Uint blk_sz;
     Uint nxt_blk_sz;
@@ -1392,7 +1998,7 @@ mbc_alloc_finalize(Allctr_t *allctr,
 		SET_PREV_BLK_FREE(allctr, nxt_nxt_blk);
 	    }
 	}
-	(*allctr->link_free_block)(allctr, nxt_blk, alcu_flgs);
+	(*allctr->link_free_block)(allctr, nxt_blk);
 
 	ASSERT(IS_NOT_LAST_BLK(blk));
 	ASSERT(IS_FREE_BLK(nxt_blk));
@@ -1433,7 +2039,8 @@ mbc_alloc_finalize(Allctr_t *allctr,
 	ASSERT(ABLK_TO_MBC(blk) == crr);
     }
 
-    STAT_MBC_BLK_ALLOC(allctr, blk_sz, alcu_flgs);
+    ERTS_ALC_CPOOL_ALLOC_OP(allctr);
+    STAT_MBC_BLK_ALLOC(allctr, crr, blk_sz, alcu_flgs);
 
     ASSERT(IS_ALLOCED_BLK(blk));
     ASSERT(blk_sz == MBC_BLK_SZ(blk));
@@ -1453,8 +2060,7 @@ mbc_alloc(Allctr_t *allctr, Uint size)
 {
     Block_t *blk;
     Uint blk_sz;
-    Uint32 alcu_flgs = 0;
-    blk = mbc_alloc_block(allctr, size, &blk_sz, &alcu_flgs);
+    blk = mbc_alloc_block(allctr, size, &blk_sz);
     if (!blk)
 	return NULL;
     if (IS_MBC_BLK(blk))
@@ -1464,35 +2070,34 @@ mbc_alloc(Allctr_t *allctr, Uint size)
 			   GET_BLK_HDR_FLGS(blk),
 			   FBLK_TO_MBC(blk),
 			   blk_sz,
-			   1,
-			   alcu_flgs);
+			   1);
     return BLK2UMEM(blk);
 }
 
 static void
-mbc_free(Allctr_t *allctr, void *p)
+mbc_free(Allctr_t *allctr, void *p, Carrier_t **busy_pcrr_pp)
 {
     Uint is_first_blk;
     Uint is_last_blk;
-    Uint32 alcu_flgs = 0;
     Uint blk_sz;
     Block_t *blk;
     Block_t *nxt_blk;
-
+    Carrier_t *crr;
 
     ASSERT(p);
 
     blk = UMEM2BLK(p);
     blk_sz = MBC_ABLK_SZ(blk);
-    if (blk_sz < allctr->sbmbc_threshold)
-	alcu_flgs |= ERTS_ALCU_FLG_SBMBC;
 
     ASSERT(IS_MBC_BLK(blk));
     ASSERT(blk_sz >= allctr->min_block_size);
 
     HARD_CHECK_BLK_CARRIER(allctr, blk);
 
-    STAT_MBC_BLK_FREE(allctr, blk_sz, alcu_flgs);
+    crr = ABLK_TO_MBC(blk);
+
+    ERTS_ALC_CPOOL_FREE_OP(allctr);
+    STAT_MBC_BLK_FREE(allctr, crr, busy_pcrr_pp, blk_sz, alcu_flgs);
 
     is_first_blk = IS_MBC_FIRST_ABLK(allctr, blk);
     is_last_blk = IS_LAST_BLK(blk);
@@ -1501,7 +2106,7 @@ mbc_free(Allctr_t *allctr, void *p)
 	ASSERT(!is_first_blk); 
 	/* Coalesce with previous block... */
 	blk = PREV_BLK(blk);
-	(*allctr->unlink_free_block)(allctr, blk, alcu_flgs);
+	(*allctr->unlink_free_block)(allctr, blk);
 
 	blk_sz += MBC_FBLK_SZ(blk);
 	is_first_blk = IS_MBC_FIRST_FBLK(allctr, blk);
@@ -1517,7 +2122,7 @@ mbc_free(Allctr_t *allctr, void *p)
 	nxt_blk = BLK_AFTER(blk, blk_sz);
 	if (IS_FREE_BLK(nxt_blk)) {
 	    /* Coalesce with next block... */
-	    (*allctr->unlink_free_block)(allctr, nxt_blk, alcu_flgs);
+	    (*allctr->unlink_free_block)(allctr, nxt_blk);
 	    blk_sz += MBC_FBLK_SZ(nxt_blk);
 	    SET_MBC_FBLK_SZ(blk, blk_sz);
 
@@ -1550,19 +2155,20 @@ mbc_free(Allctr_t *allctr, void *p)
     if (is_first_blk
 	&& is_last_blk
 	&& allctr->main_carrier != FIRST_BLK_TO_MBC(allctr, blk)) {
-	if (alcu_flgs & ERTS_ALCU_FLG_SBMBC)
-	    destroy_sbmbc(allctr, blk);
-	else
-	    destroy_carrier(allctr, blk);
+	destroy_carrier(allctr, blk, busy_pcrr_pp);
     }
     else {
-	(*allctr->link_free_block)(allctr, blk, alcu_flgs);
+	(*allctr->link_free_block)(allctr, blk);
 	HARD_CHECK_BLK_CARRIER(allctr, blk);
+#ifdef ERTS_SMP
+	check_abandon_carrier(allctr, blk, busy_pcrr_pp);
+#endif
     }
 }
 
 static void *
-mbc_realloc(Allctr_t *allctr, void *p, Uint size, Uint32 alcu_flgs)
+mbc_realloc(Allctr_t *allctr, void *p, Uint size, Uint32 alcu_flgs,
+	    Carrier_t **busy_pcrr_pp)
 {
     void *new_p;
     Uint old_blk_sz;
@@ -1576,11 +2182,6 @@ mbc_realloc(Allctr_t *allctr, void *p, Uint size, Uint32 alcu_flgs)
     Uint is_last_blk;
 #endif /* #ifndef MBC_REALLOC_ALWAYS_MOVES */
 
-#ifdef ERTS_SMP
-    if (allctr->dd.use)
-	ERTS_ALCU_HANDLE_DD_IN_OP(allctr, 1);
-#endif
-
     ASSERT(p);
     ASSERT(size);
     ASSERT(size < allctr->sbc_threshold);
@@ -1594,13 +2195,13 @@ mbc_realloc(Allctr_t *allctr, void *p, Uint size, Uint32 alcu_flgs)
     if (alcu_flgs & ERTS_ALCU_FLG_FAIL_REALLOC_MOVE)
 	return NULL;
 #else /* !MBC_REALLOC_ALWAYS_MOVES */
+
+#ifdef ERTS_SMP
+    if (busy_pcrr_pp && *busy_pcrr_pp)
+	goto realloc_move; /* Don't want to use carrier in pool */
+#endif
+
     get_blk_sz = blk_sz = UMEMSZ2BLKSZ(allctr, size);
-    if ((alcu_flgs & ERTS_ALCU_FLG_SBMBC)
-	&& (blk_sz + allctr->min_block_size > allctr->sbmbc_threshold)) {
-	/* Since we use block size to determine if blocks are
-	   located in sbmbc or not... */
-	get_blk_sz = blk_sz + allctr->min_block_size;
-    }
 
     ASSERT(IS_ALLOCED_BLK(blk));
     ASSERT(IS_MBC_BLK(blk));
@@ -1648,8 +2249,7 @@ mbc_realloc(Allctr_t *allctr, void *p, Uint size, Uint32 alcu_flgs)
 	    new_blk = (*allctr->get_free_block)(allctr,
 						get_blk_sz,
 						cand_blk,
-						cand_blk_sz,
-						alcu_flgs);
+						cand_blk_sz);
 	    if (new_blk || cand_blk != blk)
 		goto move_into_new_blk;
 	}
@@ -1671,8 +2271,11 @@ mbc_realloc(Allctr_t *allctr, void *p, Uint size, Uint32 alcu_flgs)
 
 	nxt_blk = BLK_AFTER(blk, blk_sz);
 
-	STAT_MBC_BLK_FREE(allctr, old_blk_sz, alcu_flgs);
-	STAT_MBC_BLK_ALLOC(allctr, blk_sz, alcu_flgs);
+	crr = ABLK_TO_MBC(blk);
+
+	ERTS_ALC_CPOOL_REALLOC_OP(allctr);
+	STAT_MBC_BLK_FREE(allctr, crr, NULL, old_blk_sz, alcu_flgs);
+	STAT_MBC_BLK_ALLOC(allctr, crr, blk_sz, alcu_flgs);
 
 	ASSERT(MBC_BLK_SZ(blk) >= allctr->min_block_size);
 
@@ -1680,7 +2283,7 @@ mbc_realloc(Allctr_t *allctr, void *p, Uint size, Uint32 alcu_flgs)
 	    if (IS_FREE_BLK(nxt_nxt_blk)) {
 		/* Coalesce with next free block... */
 		nxt_blk_sz += MBC_FBLK_SZ(nxt_nxt_blk);
-		(*allctr->unlink_free_block)(allctr, nxt_nxt_blk, alcu_flgs);
+		(*allctr->unlink_free_block)(allctr, nxt_nxt_blk);
 
 		is_last_blk = GET_LAST_BLK_HDR_FLG(nxt_nxt_blk);
 	    }
@@ -1690,12 +2293,11 @@ mbc_realloc(Allctr_t *allctr, void *p, Uint size, Uint32 alcu_flgs)
 	    SET_BLK_SZ_FTR(nxt_blk, nxt_blk_sz);
 	}
 
-	crr = ABLK_TO_MBC(blk);
 	SET_MBC_FBLK_HDR(nxt_blk, nxt_blk_sz,
 			SBH_THIS_FREE | (is_last_blk ? SBH_LAST_BLK : 0),
 			crr);
 
-	(*allctr->link_free_block)(allctr, nxt_blk, alcu_flgs);
+	(*allctr->link_free_block)(allctr, nxt_blk);
 
 
 	ASSERT(IS_ALLOCED_BLK(blk));
@@ -1718,6 +2320,10 @@ mbc_realloc(Allctr_t *allctr, void *p, Uint size, Uint32 alcu_flgs)
 		    
 	HARD_CHECK_BLK_CARRIER(allctr, blk);
 
+#ifdef ERTS_SMP
+	check_abandon_carrier(allctr, nxt_blk, NULL);
+#endif
+
 	return p;
     }
 
@@ -1727,11 +2333,12 @@ mbc_realloc(Allctr_t *allctr, void *p, Uint size, Uint32 alcu_flgs)
 	nxt_blk = BLK_AFTER(blk, old_blk_sz);
 	nxt_blk_sz = MBC_BLK_SZ(nxt_blk);
 	if (IS_FREE_BLK(nxt_blk) && get_blk_sz <= old_blk_sz + nxt_blk_sz) {
+	    Carrier_t* crr = ABLK_TO_MBC(blk);
 	    /* Grow into next block... */
 
 	    HARD_CHECK_BLK_CARRIER(allctr, blk);
 
-	    (*allctr->unlink_free_block)(allctr, nxt_blk, alcu_flgs);
+	    (*allctr->unlink_free_block)(allctr, nxt_blk);
 	    nxt_blk_sz -= blk_sz - old_blk_sz;
 
 	    is_last_blk = IS_LAST_BLK(nxt_blk);
@@ -1756,7 +2363,6 @@ mbc_realloc(Allctr_t *allctr, void *p, Uint size, Uint32 alcu_flgs)
 		}
 	    }
 	    else {
-		Carrier_t* crr = ABLK_TO_MBC(blk);
 		SET_MBC_ABLK_SZ(blk, blk_sz);
 
 		nxt_blk = BLK_AFTER(blk, blk_sz);
@@ -1767,15 +2373,15 @@ mbc_realloc(Allctr_t *allctr, void *p, Uint size, Uint32 alcu_flgs)
 		else
 		    SET_BLK_SZ_FTR(nxt_blk, nxt_blk_sz);
 
-		(*allctr->link_free_block)(allctr, nxt_blk, alcu_flgs);
+		(*allctr->link_free_block)(allctr, nxt_blk);
 
 		ASSERT(IS_FREE_BLK(nxt_blk));
 		ASSERT(FBLK_TO_MBC(nxt_blk) == crr);
 	    }
 
-	    STAT_MBC_BLK_FREE(allctr, old_blk_sz, alcu_flgs);
-	    STAT_MBC_BLK_ALLOC(allctr, blk_sz, alcu_flgs);
-
+	    ERTS_ALC_CPOOL_REALLOC_OP(allctr);
+	    STAT_MBC_BLK_FREE(allctr, crr, NULL, old_blk_sz, alcu_flgs);
+	    STAT_MBC_BLK_ALLOC(allctr, crr, blk_sz, alcu_flgs);
 
 	    ASSERT(IS_ALLOCED_BLK(blk));
 	    ASSERT(blk_sz == MBC_BLK_SZ(blk));
@@ -1828,13 +2434,16 @@ mbc_realloc(Allctr_t *allctr, void *p, Uint size, Uint32 alcu_flgs)
 
     if (cand_blk_sz < get_blk_sz) {
 	/* We wont fit in cand_blk get a new one */
+#ifdef ERTS_SMP
+    realloc_move:
+#endif
 #endif /* !MBC_REALLOC_ALWAYS_MOVES */
 
 	new_p = mbc_alloc(allctr, size);
 	if (!new_p)
 	    return NULL;
 	sys_memcpy(new_p, p, MIN(size, old_blk_sz - ABLK_HDR_SZ));
-	mbc_free(allctr, p);
+	mbc_free(allctr, p, busy_pcrr_pp);
 
 	return new_p;
 
@@ -1847,8 +2456,7 @@ mbc_realloc(Allctr_t *allctr, void *p, Uint size, Uint32 alcu_flgs)
 	new_blk = (*allctr->get_free_block)(allctr,
 					    get_blk_sz,
 					    cand_blk,
-					    cand_blk_sz,
-					    alcu_flgs);
+					    cand_blk_sz);
     move_into_new_blk:
 	/*
 	 * new_blk, and cand_blk have to be correctly set
@@ -1862,11 +2470,10 @@ mbc_realloc(Allctr_t *allctr, void *p, Uint size, Uint32 alcu_flgs)
 			       GET_BLK_HDR_FLGS(new_blk),
 			       FBLK_TO_MBC(new_blk),
 			       blk_sz,
-			       1,
-			       alcu_flgs);
+			       1);
 	    new_p = BLK2UMEM(new_blk);
 	    sys_memcpy(new_p, p, MIN(size, old_blk_sz - ABLK_HDR_SZ));
-	    mbc_free(allctr, p);
+	    mbc_free(allctr, p, NULL);
 	    return new_p;
 	}
 	else {
@@ -1886,7 +2493,7 @@ mbc_realloc(Allctr_t *allctr, void *p, Uint size, Uint32 alcu_flgs)
 
 	    HARD_CHECK_BLK_CARRIER(allctr, blk);
 
-	    (*allctr->unlink_free_block)(allctr, new_blk, alcu_flgs); /* prev */
+	    (*allctr->unlink_free_block)(allctr, new_blk); /* prev */
 
 	    if (is_last_blk) 
 		new_blk_flgs |= LAST_BLK_HDR_FLG;
@@ -1895,7 +2502,7 @@ mbc_realloc(Allctr_t *allctr, void *p, Uint size, Uint32 alcu_flgs)
 		if (IS_FREE_BLK(nxt_blk)) {
 		    new_blk_flgs |= GET_LAST_BLK_HDR_FLG(nxt_blk);
 		    new_blk_sz += MBC_FBLK_SZ(nxt_blk);
-		    (*allctr->unlink_free_block)(allctr, nxt_blk, alcu_flgs);
+		    (*allctr->unlink_free_block)(allctr, nxt_blk);
 		}
 	    }
 
@@ -1920,10 +2527,10 @@ mbc_realloc(Allctr_t *allctr, void *p, Uint size, Uint32 alcu_flgs)
 			       new_blk_flgs,
 			       crr,
 			       blk_sz,
-			       0,
-			       alcu_flgs);
+			       0);
 
-	    STAT_MBC_BLK_FREE(allctr, old_blk_sz, alcu_flgs);
+	    ERTS_ALC_CPOOL_FREE_OP(allctr);
+	    STAT_MBC_BLK_FREE(allctr, crr, NULL, old_blk_sz, alcu_flgs);
 
 	    return new_p;
 	}
@@ -1931,6 +2538,635 @@ mbc_realloc(Allctr_t *allctr, void *p, Uint size, Uint32 alcu_flgs)
 #endif /* !MBC_REALLOC_ALWAYS_MOVES */
 }
 
+#ifdef ERTS_SMP
+
+#define ERTS_ALC_MAX_DEALLOC_CARRIER		10
+#define ERTS_ALC_CPOOL_MAX_FETCH_INSPECT	10
+#define ERTS_ALC_CPOOL_CHECK_LIMIT_COUNT	100
+#define ERTS_ALC_CPOOL_MAX_NO_CARRIERS		5
+#define ERTS_ALC_CPOOL_INSERT_ALLOWED_OFFSET	100
+#define ERTS_ALC_CPOOL_MAX_FAILED_STAT_READS	3
+
+#define ERTS_ALC_CPOOL_PTR_MOD_MRK		(((erts_aint_t) 1) << 0)
+#define ERTS_ALC_CPOOL_PTR_DEL_MRK		(((erts_aint_t) 1) << 1)
+
+#define ERTS_ALC_CPOOL_PTR_MRKS \
+    (ERTS_ALC_CPOOL_PTR_MOD_MRK | ERTS_ALC_CPOOL_PTR_DEL_MRK)
+
+/*
+ * When setting multiple mod markers we always
+ * set mod markers in pointer order and always
+ * on next pointers before prev pointers.
+ */
+
+typedef union {
+    ErtsAlcCPoolData_t sentinel;
+    char align__[ERTS_ALC_CACHE_LINE_ALIGN_SIZE(sizeof(ErtsAlcCPoolData_t))];
+} ErtsAlcCrrPool_t;
+
+#if ERTS_ALC_A_INVALID != 0
+#  error "Carrier pool implementation assumes ERTS_ALC_A_INVALID == 0"
+#endif
+#if ERTS_ALC_A_MIN <= ERTS_ALC_A_INVALID
+#  error "Carrier pool implementation assumes ERTS_ALC_A_MIN > ERTS_ALC_A_INVALID"
+#endif
+
+/*
+ * The pool is only allowed to be manipulated by managed
+ * threads except in the alloc_SUITE:cpool case. In this
+ * test case carrier_pool[ERTS_ALC_A_INVALID] will be
+ * used.
+ */
+
+static ErtsAlcCrrPool_t carrier_pool[ERTS_ALC_A_MAX+1] erts_align_attribute(ERTS_CACHE_LINE_SIZE);
+
+#define ERTS_ALC_CPOOL_MAX_BACKOFF (1 << 8)
+
+static int
+backoff(int n)
+{
+    int i;
+
+    for (i = 0; i < n; i++)
+	ERTS_SPIN_BODY;
+
+    if (n >= ERTS_ALC_CPOOL_MAX_BACKOFF)
+	return ERTS_ALC_CPOOL_MAX_BACKOFF;
+    else
+	return n << 1;
+}
+
+static int
+cpool_dbg_is_in_pool(Allctr_t *allctr, Carrier_t *crr)
+{
+    ErtsAlcCPoolData_t *sentinel = &carrier_pool[allctr->alloc_no].sentinel;
+    ErtsAlcCPoolData_t *cpdp = sentinel;
+    Carrier_t *tmp_crr;
+
+    while (1) {
+	cpdp = (ErtsAlcCPoolData_t *) (erts_atomic_read_ddrb(&cpdp->next) & ~FLG_MASK);
+	if (cpdp == sentinel)
+	    return 0;
+	tmp_crr = (Carrier_t *) (((char *) cpdp) - offsetof(Carrier_t, cpool));
+	if (tmp_crr == crr)
+	    return 1;
+    }
+}
+
+static int
+cpool_is_empty(Allctr_t *allctr)
+{
+    ErtsAlcCPoolData_t *sentinel = &carrier_pool[allctr->alloc_no].sentinel;
+    return ((erts_atomic_read_rb(&sentinel->next) == (erts_aint_t) sentinel)
+	    && (erts_atomic_read_rb(&sentinel->prev) == (erts_aint_t) sentinel));
+}
+
+static ERTS_INLINE ErtsAlcCPoolData_t *
+cpool_aint2cpd(erts_aint_t aint)
+{
+    return (ErtsAlcCPoolData_t *) (aint & ~ERTS_ALC_CPOOL_PTR_MRKS);
+}
+
+static ERTS_INLINE erts_aint_t
+cpool_read(erts_atomic_t *aptr)
+{
+    return erts_atomic_read_acqb(aptr);
+}
+
+static ERTS_INLINE void
+cpool_init(erts_atomic_t *aptr, erts_aint_t val)
+{
+    erts_atomic_set_nob(aptr, val);
+}
+
+static ERTS_INLINE void
+cpool_set_mod_marked(erts_atomic_t *aptr, erts_aint_t new, erts_aint_t old)
+{
+#ifdef ERTS_ALC_CPOOL_DEBUG
+    erts_aint_t act = erts_atomic_xchg_relb(aptr, new);
+    ERTS_ALC_CPOOL_ASSERT(act == (old | ERTS_ALC_CPOOL_PTR_MOD_MRK));
+#else
+    erts_atomic_set_relb(aptr, new);
+#endif
+}
+
+
+static ERTS_INLINE erts_aint_t
+cpool_try_mod_mark_exp(erts_atomic_t *aptr, erts_aint_t exp)
+{
+    ERTS_ALC_CPOOL_ASSERT((exp & ERTS_ALC_CPOOL_PTR_MOD_MRK) == 0);
+    return erts_atomic_cmpxchg_nob(aptr, exp | ERTS_ALC_CPOOL_PTR_MOD_MRK, exp);
+}
+
+static ERTS_INLINE erts_aint_t
+cpool_mod_mark_exp(erts_atomic_t *aptr, erts_aint_t exp)
+{
+    int b;
+    erts_aint_t act;
+    ERTS_ALC_CPOOL_ASSERT((exp & ERTS_ALC_CPOOL_PTR_MOD_MRK) == 0);
+    while (1) {
+	act = erts_atomic_cmpxchg_nob(aptr,
+				      exp | ERTS_ALC_CPOOL_PTR_MOD_MRK,
+				      exp);
+	if (act == exp)
+	    return exp;
+	b = 1;
+	do {
+	    if ((act & ~ERTS_ALC_CPOOL_PTR_MOD_MRK) != exp)
+		return act;
+	    b = backoff(b);
+	    act = erts_atomic_read_nob(aptr);
+	} while (act != exp);
+    }
+}
+
+static ERTS_INLINE erts_aint_t
+cpool_mod_mark(erts_atomic_t *aptr)
+{
+    int b;
+    erts_aint_t act, exp;
+    act = cpool_read(aptr);
+    while (1) {
+	b = 1;
+	while (act & ERTS_ALC_CPOOL_PTR_MOD_MRK) {
+	    b = backoff(b);
+	    act = erts_atomic_read_nob(aptr);
+	}
+	exp = act;
+	act = erts_atomic_cmpxchg_acqb(aptr,
+				       exp | ERTS_ALC_CPOOL_PTR_MOD_MRK,
+				       exp);
+	if (act == exp)
+	    return exp;
+    }
+}
+
+static void
+cpool_insert(Allctr_t *allctr, Carrier_t *crr)
+{
+    ErtsAlcCPoolData_t *cpd1p, *cpd2p;
+    erts_aint_t val;
+    ErtsAlcCPoolData_t *sentinel = &carrier_pool[allctr->alloc_no].sentinel;
+
+    ERTS_ALC_CPOOL_ASSERT(allctr->alloc_no == ERTS_ALC_A_INVALID /* testcase */
+			  || erts_thr_progress_is_managed_thread());
+    ERTS_ALC_CPOOL_ASSERT(erts_smp_atomic_read_nob(&crr->allctr)
+			  == (erts_aint_t) allctr);
+
+    erts_atomic_add_nob(&allctr->cpool.stat.blocks_size,
+			(erts_aint_t) crr->cpool.blocks_size);
+    erts_atomic_add_nob(&allctr->cpool.stat.no_blocks,
+			(erts_aint_t) crr->cpool.blocks);
+    erts_atomic_add_nob(&allctr->cpool.stat.carriers_size,
+			(erts_aint_t) CARRIER_SZ(crr));
+    erts_atomic_inc_nob(&allctr->cpool.stat.no_carriers);
+
+    erts_smp_atomic_set_nob(&crr->allctr,
+			    ((erts_aint_t) allctr)|ERTS_CRR_ALCTR_FLG_IN_POOL);
+
+    /*
+     * We search in 'next' direction and begin by passing
+     * one element before trying to insert. This in order to
+     * avoid contention with threads fetching elements.
+     */
+
+    val = cpool_read(&sentinel->next);
+
+    /* Find a predecessor to be, and set mod marker on its next ptr */
+
+    while (1) {
+	cpd1p = cpool_aint2cpd(val);
+	if (cpd1p == sentinel) {
+	    val = cpool_mod_mark(&cpd1p->next);
+	    break;
+	}
+	val = cpool_read(&cpd1p->next);
+	if (!(val & ERTS_ALC_CPOOL_PTR_MRKS)) {
+	    erts_aint_t tmp = cpool_try_mod_mark_exp(&cpd1p->next, val);
+	    if (tmp == val) {
+		val = tmp;
+		break;
+	    }
+	    val = tmp;
+	}
+    }
+
+    /* Set mod marker on prev ptr of the to be successor */
+
+    cpd2p = cpool_aint2cpd(val);
+
+    cpool_init(&crr->cpool.next, (erts_aint_t) cpd2p);
+    cpool_init(&crr->cpool.prev, (erts_aint_t) cpd1p);
+
+    val = (erts_aint_t) cpd1p;
+
+    while (1) {
+	int b;
+	erts_aint_t tmp;
+
+	tmp = cpool_mod_mark_exp(&cpd2p->prev, val);
+	if (tmp == val)
+	    break;
+	b = 1;
+	do {
+	    b = backoff(b);
+	    tmp = cpool_read(&cpd2p->prev);
+	} while (tmp != val);
+    }
+
+    /* Write pointers to this element in successor and predecessor */
+
+    cpool_set_mod_marked(&cpd1p->next,
+			 (erts_aint_t) &crr->cpool,
+			 (erts_aint_t) cpd2p);
+    cpool_set_mod_marked(&cpd2p->prev,
+			 (erts_aint_t) &crr->cpool,
+			 (erts_aint_t) cpd1p);
+}
+
+static void
+cpool_delete(Allctr_t *allctr, Allctr_t *prev_allctr, Carrier_t *crr)
+{
+    ErtsAlcCPoolData_t *cpd1p, *cpd2p;
+    erts_aint_t val;
+#ifdef ERTS_ALC_CPOOL_DEBUG
+    ErtsAlcCPoolData_t *sentinel = &carrier_pool[allctr->alloc_no].sentinel;
+#endif
+
+    ERTS_ALC_CPOOL_ASSERT(allctr->alloc_no == ERTS_ALC_A_INVALID /* testcase */
+			  || erts_thr_progress_is_managed_thread());
+    ERTS_ALC_CPOOL_ASSERT(sentinel != &crr->cpool);
+
+    /* Set mod marker on next ptr of our predecessor */
+
+    val = (erts_aint_t) &crr->cpool;
+    while (1) {
+	erts_aint_t tmp;
+	cpd1p = cpool_aint2cpd(cpool_read(&crr->cpool.prev));
+	tmp = cpool_mod_mark_exp(&cpd1p->next, val);
+	if (tmp == val)
+	    break;
+    }
+
+    /* Set mod marker on our next ptr */
+
+    val = cpool_mod_mark(&crr->cpool.next);
+
+    /* Set mod marker on the prev ptr of our successor */
+
+    cpd2p = cpool_aint2cpd(val);
+
+    val = (erts_aint_t) &crr->cpool;
+
+    while (1) {
+	int b;
+	erts_aint_t tmp;
+
+	tmp = cpool_mod_mark_exp(&cpd2p->prev, val);
+	if (tmp == val)
+	    break;
+	b = 1;
+	do {
+	    b = backoff(b);
+	    tmp = cpool_read(&cpd2p->prev);
+	} while (tmp != val);
+    }
+
+    /* Set mod marker on our prev ptr */
+
+    val = (erts_aint_t) cpd1p;
+
+    while (1) {
+	int b;
+	erts_aint_t tmp;
+
+	tmp = cpool_mod_mark_exp(&crr->cpool.prev, val);
+	if (tmp == val)
+	    break;
+	b = 1;
+	do {
+	    b = backoff(b);
+	    tmp = cpool_read(&cpd2p->prev);
+	} while (tmp != val);
+    }
+
+    /* Write pointers past this element in predecessor and successor */
+
+    cpool_set_mod_marked(&cpd1p->next,
+			 (erts_aint_t) cpd2p,
+			 (erts_aint_t) &crr->cpool);
+    cpool_set_mod_marked(&cpd2p->prev,
+			 (erts_aint_t) cpd1p,
+			 (erts_aint_t) &crr->cpool);
+
+    /* Repleace mod markers with delete markers on this element */
+    cpool_set_mod_marked(&crr->cpool.next,
+			 ((erts_aint_t) cpd2p) | ERTS_ALC_CPOOL_PTR_DEL_MRK,
+			 ((erts_aint_t) cpd2p) | ERTS_ALC_CPOOL_PTR_MOD_MRK);
+    cpool_set_mod_marked(&crr->cpool.prev,
+			 ((erts_aint_t) cpd1p) | ERTS_ALC_CPOOL_PTR_DEL_MRK,
+			 ((erts_aint_t) cpd1p) | ERTS_ALC_CPOOL_PTR_MOD_MRK);
+
+    crr->cpool.thr_prgr = erts_thr_progress_later(NULL);
+
+    erts_atomic_add_nob(&prev_allctr->cpool.stat.blocks_size,
+			-((erts_aint_t) crr->cpool.blocks_size));
+    erts_atomic_add_nob(&prev_allctr->cpool.stat.no_blocks,
+			-((erts_aint_t) crr->cpool.blocks));
+    erts_atomic_add_nob(&prev_allctr->cpool.stat.carriers_size,
+			-((erts_aint_t) CARRIER_SZ(crr)));
+    erts_atomic_dec_wb(&prev_allctr->cpool.stat.no_carriers);
+
+}
+
+static Carrier_t *
+cpool_fetch(Allctr_t *allctr, UWord size)
+{
+    int i;
+    Carrier_t *crr;
+    ErtsAlcCPoolData_t *cpdp;
+    ErtsAlcCPoolData_t *sentinel = &carrier_pool[allctr->alloc_no].sentinel;
+
+    ERTS_ALC_CPOOL_ASSERT(allctr->alloc_no == ERTS_ALC_A_INVALID /* testcase */
+			  || erts_thr_progress_is_managed_thread());
+
+    i = 0;
+
+    /* First; check our own pending dealloc carrier list... */
+    crr = allctr->cpool.dc_list.last;
+    while (crr && i < ERTS_ALC_CPOOL_MAX_FETCH_INSPECT) {
+	if (erts_atomic_read_nob(&crr->cpool.max_size) >= size) {
+	    unlink_carrier(&allctr->cpool.dc_list, crr);
+#ifdef ERTS_ALC_CPOOL_DEBUG
+	    ERTS_ALC_CPOOL_ASSERT(erts_smp_atomic_xchg_nob(&crr->allctr,
+							   ((erts_aint_t) allctr))
+				  == (((erts_aint_t) allctr) & ~FLG_MASK));
+#else
+	    erts_smp_atomic_set_nob(&crr->allctr, ((erts_aint_t) allctr));
+#endif
+	    return crr;
+	}
+	crr = crr->prev;
+	i++;
+    }
+
+    /* ... then the pool ... */
+
+    /*
+     * We search in 'prev' direction and begin by passing
+     * one element before trying to fetch. This in order to
+     * avoid contention with threads inserting elements.
+     */
+
+    cpdp = cpool_aint2cpd(cpool_read(&sentinel->prev));
+    if (cpdp == sentinel)
+	return NULL;
+
+    while (i < ERTS_ALC_CPOOL_MAX_FETCH_INSPECT) {
+	erts_aint_t exp;
+	cpdp = cpool_aint2cpd(cpool_read(&cpdp->prev));
+	if (cpdp == sentinel) {
+	    cpdp = cpool_aint2cpd(cpool_read(&cpdp->prev));
+	    if (cpdp == sentinel)
+		return NULL;
+	    i = ERTS_ALC_CPOOL_MAX_FETCH_INSPECT; /* Last one to inspect */
+	}
+	crr = (Carrier_t *) (((char *) cpdp) - offsetof(Carrier_t, cpool));
+	exp = erts_smp_atomic_read_rb(&crr->allctr);
+	if (((exp & (ERTS_CRR_ALCTR_FLG_IN_POOL|ERTS_CRR_ALCTR_FLG_BUSY))
+	     == ERTS_CRR_ALCTR_FLG_IN_POOL)
+	    && (erts_atomic_read_nob(&cpdp->max_size) >= size)) {
+	    erts_aint_t act;
+	    /* Try to fetch it... */
+	    act = erts_smp_atomic_cmpxchg_mb(&crr->allctr,
+					     (erts_aint_t) allctr,
+					     exp);
+	    if (act == exp) {
+		cpool_delete(allctr, ((Allctr_t *) (act & ~FLG_MASK)), crr);
+		return crr;
+	    }
+	}
+	i++;
+    }
+    return NULL;
+}
+
+static void
+check_pending_dealloc_carrier(Allctr_t *allctr,
+			      int *need_thr_progress,
+			      ErtsThrPrgrVal *thr_prgr_p,
+			      int *need_more_work)
+{
+    Carrier_t *crr = allctr->cpool.dc_list.first;
+
+    if (crr) {
+	ErtsThrPrgrVal current = erts_thr_progress_current();
+	int i = 0;
+
+	do {
+	    Carrier_t *dcrr;
+
+	    if (!erts_thr_progress_has_reached_this(current, crr->cpool.thr_prgr))
+		break;
+
+	    dcrr = crr;
+	    crr = crr->next;
+	    dealloc_carrier(allctr, dcrr, ERTS_MSEG_FLG_2POW);
+	    i++;
+	} while (crr && i < ERTS_ALC_MAX_DEALLOC_CARRIER);
+
+	allctr->cpool.dc_list.first = crr;
+	if (!crr)
+	    allctr->cpool.dc_list.last = NULL;
+	else {
+	    crr->prev = NULL;
+
+	    if (need_more_work) {
+		ERTS_ALC_CPOOL_ASSERT(need_thr_progress && thr_prgr_p);
+		if (erts_thr_progress_has_reached_this(current, crr->cpool.thr_prgr))
+		    *need_more_work = 1;
+		else {
+		    *need_thr_progress = 1;
+		    if (*thr_prgr_p == ERTS_THR_PRGR_INVALID
+			|| erts_thr_progress_cmp(crr->cpool.thr_prgr,
+						 *thr_prgr_p) < 0) {
+			*thr_prgr_p = crr->cpool.thr_prgr;
+		    }
+		}
+	    }
+	}
+    }
+}
+
+static void
+schedule_dealloc_carrier(Allctr_t *allctr, Carrier_t *crr)
+{
+    Allctr_t *used_allctr;
+    int check_pending_dealloc;
+    erts_aint_t max_size;
+
+    if (!ERTS_ALC_IS_CPOOL_ENABLED(allctr)) {
+	dealloc_carrier(allctr, crr, ERTS_MSEG_FLG_2POW);
+	return;
+    }
+
+    used_allctr = crr->cpool.orig_allctr;
+
+    if (allctr != used_allctr) {
+	Block_t *blk = MBC_TO_FIRST_BLK(allctr, crr);
+	int cinit = used_allctr->dd.ix - allctr->dd.ix;
+
+	/*
+	 * Receiver will recognize that this is a carrier to
+	 * deallocate since the block is an mbc block that
+	 * is free and last in carrier...
+	 */
+	ERTS_ALC_CPOOL_ASSERT(IS_FREE_LAST_MBC_BLK(blk));
+
+	ERTS_ALC_CPOOL_ASSERT(IS_MBC_FIRST_ABLK(allctr, blk));
+	ERTS_ALC_CPOOL_ASSERT(crr == FBLK_TO_MBC(blk));
+	ERTS_ALC_CPOOL_ASSERT(crr == FIRST_BLK_TO_MBC(used_allctr, blk));
+
+	if (ddq_enqueue(&used_allctr->dd.q, BLK2UMEM(blk), cinit))
+	    erts_alloc_notify_delayed_dealloc(used_allctr->ix);
+	return;
+    }
+
+    if (crr->cpool.thr_prgr == ERTS_THR_PRGR_INVALID
+	|| erts_thr_progress_has_reached(crr->cpool.thr_prgr)) {
+	dealloc_carrier(allctr, crr, ERTS_MSEG_FLG_2POW);
+	return;
+    }
+
+    max_size = (erts_aint_t) allctr->largest_fblk_in_mbc(allctr, crr);
+    erts_atomic_set_nob(&crr->cpool.max_size, max_size);
+
+    crr->next = NULL;
+    crr->prev = allctr->cpool.dc_list.last;
+    if (allctr->cpool.dc_list.last) {
+	check_pending_dealloc = 1;
+	allctr->cpool.dc_list.last->next = crr;
+    }
+    else {
+	check_pending_dealloc = 0;
+	allctr->cpool.dc_list.first = crr;
+    }
+    allctr->cpool.dc_list.last = crr;
+    if (check_pending_dealloc)
+	check_pending_dealloc_carrier(allctr, NULL, NULL, NULL);
+    erts_alloc_ensure_handle_delayed_dealloc_call(allctr->ix);
+}
+
+static ERTS_INLINE void
+cpool_init_carrier_data(Allctr_t *allctr, Carrier_t *crr)
+{
+    erts_atomic_init_nob(&crr->cpool.next, ERTS_AINT_NULL);
+    erts_atomic_init_nob(&crr->cpool.prev, ERTS_AINT_NULL);
+    crr->cpool.orig_allctr = allctr;
+    crr->cpool.thr_prgr = ERTS_THR_PRGR_INVALID;
+    erts_atomic_init_nob(&crr->cpool.max_size, 0);
+    crr->cpool.blocks = 0;
+    crr->cpool.blocks_size = 0;
+    if (!ERTS_ALC_IS_CPOOL_ENABLED(allctr))
+	crr->cpool.abandon_limit = 0;
+    else {
+	UWord csz = CARRIER_SZ(crr);
+	UWord limit = csz*allctr->cpool.util_limit;
+	if (limit > csz)
+	    limit /= 100;
+	else
+	    limit = (csz/100)*allctr->cpool.util_limit;
+	crr->cpool.abandon_limit = limit;
+    }
+}
+
+static void
+set_new_allctr_abandon_limit(Allctr_t *allctr)
+{
+    UWord limit;
+    UWord csz;
+
+    allctr->cpool.check_limit_count = ERTS_ALC_CPOOL_CHECK_LIMIT_COUNT;
+
+    csz = allctr->mbcs.curr.norm.mseg.size;
+    csz += allctr->mbcs.curr.norm.sys_alloc.size;
+
+    limit = csz*allctr->cpool.util_limit;
+    if (limit > csz)
+	limit /= 100;
+    else
+	limit = (csz/100)*allctr->cpool.util_limit;
+
+    allctr->cpool.abandon_limit = limit;
+}
+
+static void
+abandon_carrier(Allctr_t *allctr, Carrier_t *crr)
+{
+    erts_aint_t max_size;
+
+    STAT_MBC_CPOOL_INSERT(allctr, crr);
+
+    unlink_carrier(&allctr->mbc_list, crr);
+
+    allctr->remove_mbc(allctr, crr);
+
+    max_size = (erts_aint_t) allctr->largest_fblk_in_mbc(allctr, crr);
+    erts_atomic_set_nob(&crr->cpool.max_size, max_size);
+
+    cpool_insert(allctr, crr);
+
+    set_new_allctr_abandon_limit(allctr);
+}
+
+static void
+cpool_read_stat(Allctr_t *allctr, UWord *nocp, UWord *cszp, UWord *nobp, UWord *bszp)
+{
+    int i;
+    UWord noc = 0, csz = 0, nob = 0, bsz = 0;
+
+    /*
+     * We try to get consistent values, but after
+     * ERTS_ALC_CPOOL_MAX_FAILED_STAT_READS failed
+     * tries we give up and present what we got...
+     */
+    for (i = 0; i <= ERTS_ALC_CPOOL_MAX_FAILED_STAT_READS; i++) {
+	UWord tnoc, tcsz, tnob, tbsz;
+
+	tnoc = (UWord) (nocp
+			? erts_atomic_read_nob(&allctr->cpool.stat.no_carriers)
+			: 0);
+	tcsz = (UWord) (cszp
+			? erts_atomic_read_nob(&allctr->cpool.stat.carriers_size)
+			: 0);
+	tnob = (UWord) (nobp
+			? erts_atomic_read_nob(&allctr->cpool.stat.no_blocks)
+			: 0);
+	tbsz = (UWord) (bszp
+			? erts_atomic_read_nob(&allctr->cpool.stat.blocks_size)
+			: 0);
+	if (tnoc == noc && tcsz == csz && tnob == nob && tbsz == bsz)
+	    break;
+	noc = tnoc;
+	csz = tcsz;
+	nob = tnob;
+	bsz = tbsz;
+	ERTS_THR_READ_MEMORY_BARRIER;
+    }
+
+    if (nocp)
+	*nocp = noc;
+    if (cszp)
+	*cszp = csz;
+    if (nobp)
+	*nobp = nob;
+    if (bszp)
+	*bszp = bsz;
+}
+
+
+#endif /* ERTS_SMP */
+
 #ifdef DEBUG
 
 #if HAVE_ERTS_MSEG
@@ -1974,81 +3210,6 @@ static void CHECK_1BLK_CARRIER(Allctr_t* A, int SBC, int MSEGED, Carrier_t* C,
 #endif
 
 static Block_t *
-create_sbmbc(Allctr_t *allctr, Uint umem_sz)
-{
-    Block_t *blk;
-    Uint blk_sz;
-    Uint crr_sz = allctr->sbmbc_size;
-    Carrier_t *crr;
-
-#if HALFWORD_HEAP
-    if (allctr->mseg_opt.low_mem)
-	crr = erts_alloc(ERTS_ALC_T_SBMBC_LOW, crr_sz);
-    else
-#endif
-	crr = erts_alloc(ERTS_ALC_T_SBMBC, crr_sz);
-
-    INC_CC(allctr->calls.sbmbc_alloc);
-    SET_CARRIER_HDR(crr, crr_sz, SCH_SYS_ALLOC|SCH_MBC, allctr);
-
-    blk = MBC_TO_FIRST_BLK(allctr, crr);
-
-    blk_sz = UNIT_FLOOR(crr_sz - MBC_HEADER_SIZE(allctr));
-
-    SET_MBC_FBLK_HDR(blk, blk_sz, SBH_THIS_FREE|SBH_LAST_BLK, crr);
-
-    link_carrier(&allctr->sbmbc_list, crr);
-
-    STAT_SBMBC_ALLOC(allctr, crr_sz);
-    CHECK_1BLK_CARRIER(allctr, 0, 0, crr, crr_sz, blk, blk_sz);
-    if (allctr->creating_mbc)
-	(*allctr->creating_mbc)(allctr, crr, ERTS_ALCU_FLG_SBMBC);
-
-    DEBUG_SAVE_ALIGNMENT(crr);
-    return blk;
-}
-
-static void
-destroy_sbmbc(Allctr_t *allctr, Block_t *blk)
-{
-    Uint crr_sz;
-    Carrier_t *crr;
-
-    ASSERT(IS_MBC_BLK(blk));
-    ASSERT(IS_MBC_FIRST_FBLK(allctr, blk));
-
-    crr = FIRST_BLK_TO_MBC(allctr, blk);
-    crr_sz = CARRIER_SZ(crr);
-
-#ifdef DEBUG
-    if (!allctr->stopped) {
-	ASSERT(IS_LAST_BLK(blk));
-
-#ifdef ERTS_ALLOC_UTIL_HARD_DEBUG
-	(*allctr->link_free_block)(allctr, blk, ERTS_ALCU_FLG_SBMBC);
-	HARD_CHECK_BLK_CARRIER(allctr, blk);
-	(*allctr->unlink_free_block)(allctr, blk, ERTS_ALCU_FLG_SBMBC);
-#endif
-    }
-#endif
-
-    STAT_SBMBC_FREE(allctr, crr_sz);
-
-    unlink_carrier(&allctr->sbmbc_list, crr);
-    if (allctr->destroying_mbc)
-	(*allctr->destroying_mbc)(allctr, crr, ERTS_ALCU_FLG_SBMBC);
-
-    INC_CC(allctr->calls.sbmbc_free);
-
-#if HALFWORD_HEAP
-    if (allctr->mseg_opt.low_mem)
-	erts_free(ERTS_ALC_T_SBMBC_LOW, crr);
-    else
-#endif
-	erts_free(ERTS_ALC_T_SBMBC, crr);
-}
-
-static Block_t *
 create_carrier(Allctr_t *allctr, Uint umem_sz, UWord flags)
 {
     Block_t *blk;
@@ -2077,6 +3238,24 @@ create_carrier(Allctr_t *allctr, Uint umem_sz, UWord flags)
 
     blk_sz = UMEMSZ2BLKSZ(allctr, umem_sz);
 
+#ifdef ERTS_SMP
+    allctr->cpool.disable_abandon = ERTS_ALC_CPOOL_MAX_DISABLE_ABANDON;
+
+    if ((flags & (CFLG_MBC|CFLG_NO_CPOOL)) == CFLG_MBC
+	&& ERTS_ALC_IS_CPOOL_ENABLED(allctr)
+	&& erts_thr_progress_is_managed_thread()) {
+	crr = cpool_fetch(allctr, blk_sz);
+	if (crr) {
+	    STAT_MBC_CPOOL_FETCH(allctr, crr);
+	    link_carrier(&allctr->mbc_list, crr);
+	    (*allctr->add_mbc)(allctr, crr);
+	    blk = (*allctr->get_free_block)(allctr, blk_sz, NULL, 0);
+	    ASSERT(blk);
+	    return blk;
+	}
+    }
+#endif
+
 #if HAVE_ERTS_MSEG
 
     if (flags & CFLG_FORCE_SYS_ALLOC)
@@ -2204,11 +3383,15 @@ create_carrier(Allctr_t *allctr, Uint umem_sz, UWord flags)
 	    allctr->main_carrier = crr;
 	}
 
+#ifdef ERTS_SMP
+	cpool_init_carrier_data(allctr, crr);
+#endif
+
 	link_carrier(&allctr->mbc_list, crr);
 
 	CHECK_1BLK_CARRIER(allctr, 0, is_mseg, crr, crr_sz, blk, blk_sz);
 	if (allctr->creating_mbc)
-	    (*allctr->creating_mbc)(allctr, crr, 0);
+	    (*allctr->creating_mbc)(allctr, crr);
 
     }
 
@@ -2352,14 +3535,21 @@ resize_carrier(Allctr_t *allctr, Block_t *old_blk, Uint umem_sz, UWord flags)
 }
 
 static void
-destroy_carrier(Allctr_t *allctr, Block_t *blk)
+dealloc_carrier(Allctr_t *allctr, Carrier_t *crr, Uint mseg_flags)
 {
-    Uint crr_sz;
-    Carrier_t *crr;
 #if HAVE_ERTS_MSEG
-    Uint is_mseg = 0;
-    Uint mseg_flags = ERTS_MSEG_FLG_NONE;
+    if (IS_MSEG_CARRIER(crr))
+	alcu_mseg_dealloc(allctr, crr, CARRIER_SZ(crr), mseg_flags);
+    else
 #endif
+	alcu_sys_free(allctr, crr);
+}
+
+static void
+destroy_carrier(Allctr_t *allctr, Block_t *blk, Carrier_t **busy_pcrr_pp)
+{
+    Uint crr_sz;
+    Carrier_t *crr;
 
     if (IS_SBC_BLK(blk)) {
 	Uint blk_sz = SBC_BLK_SZ(blk);
@@ -2372,7 +3562,6 @@ destroy_carrier(Allctr_t *allctr, Block_t *blk)
 
 #if HAVE_ERTS_MSEG
 	if (IS_MSEG_CARRIER(crr)) {
-	    is_mseg++;
 	    ASSERT(crr_sz % MSEG_UNIT_SZ == 0);
 	    STAT_MSEG_SBC_FREE(allctr, crr_sz, blk_sz);
 	}
@@ -2382,6 +3571,7 @@ destroy_carrier(Allctr_t *allctr, Block_t *blk)
 
 	unlink_carrier(&allctr->sbc_list, crr);
 
+	dealloc_carrier(allctr, crr, ERTS_MSEG_FLG_NONE);
     }
     else {
 	ASSERT(IS_MBC_FIRST_FBLK(allctr, blk));
@@ -2400,30 +3590,36 @@ destroy_carrier(Allctr_t *allctr, Block_t *blk)
 	}
 #endif
 
-#if HAVE_ERTS_MSEG
-	if (IS_MSEG_CARRIER(crr)) {
-	    is_mseg++;
-	    ASSERT(crr_sz % MSEG_UNIT_SZ == 0);
-	    STAT_MSEG_MBC_FREE(allctr, crr_sz);
-	    mseg_flags = ERTS_MSEG_FLG_2POW;
+	if (allctr->destroying_mbc)
+	    (*allctr->destroying_mbc)(allctr, crr);
+
+#ifdef ERTS_SMP
+	if (busy_pcrr_pp && *busy_pcrr_pp) {
+	    ERTS_ALC_CPOOL_ASSERT(*busy_pcrr_pp == crr);
+	    *busy_pcrr_pp = NULL;
+	    cpool_delete(allctr, allctr, crr);
 	}
 	else
 #endif
-	    STAT_SYS_ALLOC_MBC_FREE(allctr, crr_sz);
+	{
+	    unlink_carrier(&allctr->mbc_list, crr);
+#if HAVE_ERTS_MSEG
+	    if (IS_MSEG_CARRIER(crr)) {
+		ASSERT(crr_sz % MSEG_UNIT_SZ == 0);
+		STAT_MSEG_MBC_FREE(allctr, crr_sz);
+	    }
+	    else
+#endif
+		STAT_SYS_ALLOC_MBC_FREE(allctr, crr_sz);
+	}
 
-	unlink_carrier(&allctr->mbc_list, crr);
-	if (allctr->destroying_mbc)
-	    (*allctr->destroying_mbc)(allctr, crr, 0);
+#ifdef ERTS_SMP
+	schedule_dealloc_carrier(allctr, crr);
+#else
+	dealloc_carrier(allctr, crr, ERTS_MSEG_FLG_2POW);
+#endif
     }
 
-
-#if HAVE_ERTS_MSEG
-    if (is_mseg) {
-	alcu_mseg_dealloc(allctr, crr, crr_sz, mseg_flags);
-    }
-    else
-#endif
-	alcu_sys_free(allctr, crr);
 }
 
 
@@ -2457,19 +3653,19 @@ static struct {
     Eterm lmbcs;
     Eterm smbcs;
     Eterm mbcgs;
-    Eterm sbmbcs;
-    Eterm sbmbct;
+    Eterm acul;
 
 #if HAVE_ERTS_MSEG
     Eterm mmc;
 #endif
     Eterm ycs;
 
-    /* Eterm sbmbcs; */
-
     Eterm fix_types;
 
     Eterm mbcs;
+#ifdef ERTS_SMP
+    Eterm mbcs_pool;
+#endif
     Eterm sbcs;
 
     Eterm sys_alloc_carriers_size;
@@ -2494,8 +3690,6 @@ static struct {
     Eterm mseg_dealloc;
     Eterm mseg_realloc;
 #endif
-    Eterm sbmbc_alloc;
-    Eterm sbmbc_free;
 #ifdef DEBUG
     Eterm end_of_atoms;
 #endif
@@ -2551,19 +3745,19 @@ init_atoms(Allctr_t *allctr)
 	AM_INIT(lmbcs);
 	AM_INIT(smbcs);
 	AM_INIT(mbcgs);
-	AM_INIT(sbmbcs);
-	AM_INIT(sbmbct);
+	AM_INIT(acul);
 
 #if HAVE_ERTS_MSEG
 	AM_INIT(mmc);
 #endif
 	AM_INIT(ycs);
 
-	/*AM_INIT(sbmbcs);*/
-
 	AM_INIT(fix_types);
 
 	AM_INIT(mbcs);
+#ifdef ERTS_SMP
+	AM_INIT(mbcs_pool);
+#endif
 	AM_INIT(sbcs);
 
 	AM_INIT(sys_alloc_carriers_size);
@@ -2588,8 +3782,6 @@ init_atoms(Allctr_t *allctr)
 	AM_INIT(mseg_dealloc);
 	AM_INIT(mseg_realloc);
 #endif
-	AM_INIT(sbmbc_free);
-	AM_INIT(sbmbc_alloc);
 
 #ifdef DEBUG
 	for (atom = (Eterm *) &am; atom < &am.end_of_atoms; atom++) {
@@ -2637,19 +3829,22 @@ ensure_atoms_initialized(Allctr_t *allctr)
  * that would fit a small when size check is done may need to be built
  * as a big when the actual build is performed. Caller is required to
  * HRelease after build.
+ *
+ * Note, bld_unstable_uint() should have been called bld_unstable_uword()
+ * but we do not want to rename it...
  */
 static ERTS_INLINE Eterm
-bld_unstable_uint(Uint **hpp, Uint *szp, Uint ui)
+bld_unstable_uint(Uint **hpp, Uint *szp, UWord ui)
 {
     Eterm res = THE_NON_VALUE;
     if (szp)
-	*szp += BIG_UINT_HEAP_SIZE;
+	*szp += BIG_UWORD_HEAP_SIZE(~((UWord) 0));
     if (hpp) {
 	if (IS_USMALL(0, ui))
 	    res = make_small(ui);
 	else {
-	    res = uint_to_big(ui, *hpp);
-	    *hpp += BIG_UINT_HEAP_SIZE;
+	    res = uword_to_big(ui, *hpp);
+	    *hpp += BIG_UWORD_HEAP_SIZE(ui);
 	}
     }
     return res;
@@ -2675,8 +3870,24 @@ add_4tup(Uint **hpp, Uint *szp, Eterm *lp,
 	bld_cons(hpp, szp, bld_tuple(hpp, szp, 4, el1, el2, el3, el4), *lp);
 }
 
+static ERTS_INLINE void
+add_fix_types(Allctr_t *allctr, int internal, Uint **hpp, Uint *szp,
+	      Eterm *lp, Eterm fix)
+{
+    if (allctr->fix) {
+	if (!ERTS_ALC_IS_CPOOL_ENABLED(allctr))
+	    add_2tup(hpp, szp, lp, am.fix_types, fix);
+	else if (internal)
+	    add_3tup(hpp, szp, lp,
+		     am.fix_types,
+		     erts_bld_uword(hpp, szp, ~((UWord) 0)),
+		     fix);
+    }
+}
+
 static Eterm
 sz_info_fix(Allctr_t *allctr,
+	    int internal,
 	    int *print_to_p,
 	    void *print_to_arg,
 	    Uint **hpp,
@@ -2684,36 +3895,67 @@ sz_info_fix(Allctr_t *allctr,
 {
     Eterm res;
     int ix;
-    ErtsAlcFixList_t *fix = allctr->fix;
 
-    ASSERT(fix);
+    ASSERT(allctr->fix);
 
     res = NIL;
 
-    for (ix = ERTS_ALC_NO_FIXED_SIZES-1; ix >= 0; ix--) {
-	ErtsAlcType_t n = ix + ERTS_ALC_N_MIN_A_FIXED_SIZE;
-	Uint alloced = (fix[ix].type_size * fix[ix].allocated);
-	Uint used = fix[ix].type_size*fix[ix].used;
-
-	if (print_to_p) {
-	    int to = *print_to_p;
-	    void *arg = print_to_arg;
-	    erts_print(to,
-		       arg,
-		       "fix type: %s %bpu %bpu\n",
-		       (char *) ERTS_ALC_N2TD(n),
-		       alloced,
-		       used);
-	}
+    if (ERTS_ALC_IS_CPOOL_ENABLED(allctr)) {
+
+	if (internal) {
+	    for (ix = ERTS_ALC_NO_FIXED_SIZES-1; ix >= 0; ix--) {
+		ErtsAlcFixList_t *fix = &allctr->fix[ix];
+		UWord alloced = fix->type_size * fix->u.cpool.allocated;
+		UWord used = fix->type_size * fix->u.cpool.used;
+
+		if (print_to_p) {
+		    int to = *print_to_p;
+		    void *arg = print_to_arg;
+		    erts_print(to,
+			       arg,
+			       "fix type internal: %s %bpu %bpu\n",
+			       (char *) ERTS_ALC_N2TD(ERTS_ALC_N_MIN_A_FIXED_SIZE
+						      + ix),
+			       alloced,
+			       used);
+		}
 
-	if (hpp || szp) {
-	    add_3tup(hpp, szp, &res,
-		     fix_type_atoms[ix],
-		     bld_unstable_uint(hpp, szp, alloced),
-		     bld_unstable_uint(hpp, szp, used));
+		if (hpp || szp) {
+		    add_3tup(hpp, szp, &res,
+			     fix_type_atoms[ix],
+			     bld_unstable_uint(hpp, szp, alloced),
+			     bld_unstable_uint(hpp, szp, used));
+		}
+	    }
 	}
     }
+    else {
 
+	for (ix = ERTS_ALC_NO_FIXED_SIZES-1; ix >= 0; ix--) {
+	    ErtsAlcFixList_t *fix = &allctr->fix[ix];
+	    UWord alloced = fix->type_size * fix->u.nocpool.allocated;
+	    UWord used = fix->type_size*fix->u.nocpool.used;
+
+	    if (print_to_p) {
+		int to = *print_to_p;
+		void *arg = print_to_arg;
+		erts_print(to,
+			   arg,
+			   "fix type: %s %bpu %bpu\n",
+			   (char *) ERTS_ALC_N2TD(ERTS_ALC_N_MIN_A_FIXED_SIZE
+						  + ix),
+			   alloced,
+			   used);
+	    }
+
+	    if (hpp || szp) {
+		add_3tup(hpp, szp, &res,
+			 fix_type_atoms[ix],
+			 bld_unstable_uint(hpp, szp, alloced),
+			 bld_unstable_uint(hpp, szp, used));
+	    }
+	}
+    }
     return res;
 }
 
@@ -2727,9 +3969,7 @@ sz_info_carriers(Allctr_t *allctr,
 		 Uint *szp)
 {
     Eterm res = THE_NON_VALUE;
-    Uint curr_size = (cs == &allctr->sbmbcs
-		      ? cs->curr.small_block.size
-		      : cs->curr.norm.mseg.size + cs->curr.norm.sys_alloc.size);
+    UWord curr_size = cs->curr.norm.mseg.size + cs->curr.norm.sys_alloc.size;
 
     if (print_to_p) {
 	int to = *print_to_p;
@@ -2743,7 +3983,7 @@ sz_info_carriers(Allctr_t *allctr,
 		   cs->blocks.max_ever.size);
 	erts_print(to,
 		   arg,
-		   "%scarriers size: %beu %bpu %bpu\n",
+		   "%scarriers size: %bpu %bpu %bpu\n",
 		   prefix,
 		   curr_size,
 		   cs->max.size,
@@ -2767,6 +4007,62 @@ sz_info_carriers(Allctr_t *allctr,
     return res;
 }
 
+#ifdef ERTS_SMP
+
+static Eterm
+info_cpool(Allctr_t *allctr,
+	   int sz_only,
+	   char *prefix,
+	   int *print_to_p,
+	   void *print_to_arg,
+	   Uint **hpp,
+	   Uint *szp)
+{
+    Eterm res = THE_NON_VALUE;
+    UWord noc, csz, nob, bsz;
+
+    noc = csz = nob = bsz = ~0;
+    if (print_to_p || hpp) {
+	if (sz_only)
+	    cpool_read_stat(allctr, NULL, &csz, NULL, &bsz);
+	else
+	    cpool_read_stat(allctr, &noc, &csz, &nob, &bsz);
+    }
+
+    if (print_to_p) {
+	int to = *print_to_p;
+	void *arg = print_to_arg;
+	if (!sz_only)
+	    erts_print(to, arg, "%sblocks: %bpu\n", prefix, nob);
+	erts_print(to, arg, "%sblocks size: %bpu\n", prefix, bsz);
+	if (!sz_only)
+	    erts_print(to, arg, "%scarriers: %bpu\n", prefix, noc);
+	erts_print(to, arg, "%scarriers size: %bpu\n", prefix, csz);
+    }
+
+    if (hpp || szp) {
+	res = NIL;
+	add_2tup(hpp, szp, &res,
+		 am.carriers_size,
+		 bld_unstable_uint(hpp, szp, csz));
+	if (!sz_only)
+	    add_2tup(hpp, szp, &res,
+		     am.carriers,
+		     bld_unstable_uint(hpp, szp, noc));
+	add_2tup(hpp, szp, &res,
+		 am.blocks_size,
+		 bld_unstable_uint(hpp, szp, bsz));
+	if (!sz_only)
+	    add_2tup(hpp, szp, &res,
+		     am.blocks,
+		     bld_unstable_uint(hpp, szp, nob));
+    }
+
+    return res;
+}
+
+#endif /* ERTS_SMP */
+
 static Eterm
 info_carriers(Allctr_t *allctr,
 	      CarriersStats_t *cs,
@@ -2777,17 +4073,10 @@ info_carriers(Allctr_t *allctr,
 	      Uint *szp)
 {
     Eterm res = THE_NON_VALUE;
-    Uint curr_no, curr_size;
-    int small_block = cs == &allctr->sbmbcs;
-
-    if (small_block) {
-	curr_no = cs->curr.small_block.no;
-	curr_size = cs->curr.small_block.size;
-    }
-    else {
-	curr_no = cs->curr.norm.mseg.no + cs->curr.norm.sys_alloc.no;
-	curr_size = cs->curr.norm.mseg.size + cs->curr.norm.sys_alloc.size;
-    }
+    UWord curr_no, curr_size;
+    
+    curr_no = cs->curr.norm.mseg.no + cs->curr.norm.sys_alloc.no;
+    curr_size = cs->curr.norm.mseg.size + cs->curr.norm.sys_alloc.size;
 
     if (print_to_p) {
 	int to = *print_to_p;
@@ -2808,75 +4097,67 @@ info_carriers(Allctr_t *allctr,
 		   cs->blocks.max_ever.size);
 	erts_print(to,
 		   arg,
-		   "%scarriers: %beu %bpu %bpu\n",
+		   "%scarriers: %bpu %bpu %bpu\n",
 		   prefix,
 		   curr_no,
 		   cs->max.no,
 		   cs->max_ever.no);
-	if (!small_block) {
 #if HAVE_ERTS_MSEG
-	    erts_print(to,
-		       arg,
-		       "%smseg carriers: %bpu\n",
-		       prefix,
-		       cs->curr.norm.mseg.no);
-#endif
-	    erts_print(to,
-		       arg,
-		       "%ssys_alloc carriers: %bpu\n",
-		       prefix,
-		       cs->curr.norm.sys_alloc.no);
-	}
 	erts_print(to,
 		   arg,
-		   "%scarriers size: %beu %bpu %bpu\n",
+		   "%smseg carriers: %bpu\n",
+		   prefix,
+		   cs->curr.norm.mseg.no);
+#endif
+	erts_print(to,
+		   arg,
+		   "%ssys_alloc carriers: %bpu\n",
+		   prefix,
+		   cs->curr.norm.sys_alloc.no);
+	erts_print(to,
+		   arg,
+		   "%scarriers size: %bpu %bpu %bpu\n",
 		   prefix,
 		   curr_size,
 		   cs->max.size,
 		   cs->max_ever.size);
-	if (!small_block) {
 #if HAVE_ERTS_MSEG
-	    erts_print(to,
-		       arg,
-		       "%smseg carriers size: %bpu\n",
-		       prefix,
-		       cs->curr.norm.mseg.size);
-#endif
-	    erts_print(to,
-		       arg,
-		       "%ssys_alloc carriers size: %bpu\n",
-		       prefix,
-		       cs->curr.norm.sys_alloc.size);
-	}
+	erts_print(to,
+		   arg,
+		   "%smseg carriers size: %bpu\n",
+		   prefix,
+		   cs->curr.norm.mseg.size);
+#endif
+	erts_print(to,
+		   arg,
+		   "%ssys_alloc carriers size: %bpu\n",
+		   prefix,
+		   cs->curr.norm.sys_alloc.size);
     }
 
     if (hpp || szp) {
 	res = NIL;
-	if (!small_block) {
-	    add_2tup(hpp, szp, &res,
-		     am.sys_alloc_carriers_size,
-		     bld_unstable_uint(hpp, szp, cs->curr.norm.sys_alloc.size));
+	add_2tup(hpp, szp, &res,
+		 am.sys_alloc_carriers_size,
+		 bld_unstable_uint(hpp, szp, cs->curr.norm.sys_alloc.size));
 #if HAVE_ERTS_MSEG
-	    add_2tup(hpp, szp, &res,
-		     am.mseg_alloc_carriers_size,
-		     bld_unstable_uint(hpp, szp, cs->curr.norm.mseg.size));
+	add_2tup(hpp, szp, &res,
+		 am.mseg_alloc_carriers_size,
+		 bld_unstable_uint(hpp, szp, cs->curr.norm.mseg.size));
 #endif
-	}
 	add_4tup(hpp, szp, &res,
 		 am.carriers_size,
 		 bld_unstable_uint(hpp, szp, curr_size),
 		 bld_unstable_uint(hpp, szp, cs->max.size),
 		 bld_unstable_uint(hpp, szp, cs->max_ever.size));
-	if (!small_block) {
-	    add_2tup(hpp, szp, &res,
-		     am.sys_alloc_carriers,
-		     bld_unstable_uint(hpp, szp, cs->curr.norm.sys_alloc.no));
+	add_2tup(hpp, szp, &res,
+		 am.sys_alloc_carriers,
+		 bld_unstable_uint(hpp, szp, cs->curr.norm.sys_alloc.no));
 #if HAVE_ERTS_MSEG
-	    add_2tup(hpp, szp, &res,
-		     am.mseg_alloc_carriers,
-		     bld_unstable_uint(hpp, szp, cs->curr.norm.mseg.no));
+	add_2tup(hpp, szp, &res,
+		 am.mseg_alloc_carriers,
+		 bld_unstable_uint(hpp, szp, cs->curr.norm.mseg.no));
 #endif
-	}
 	add_4tup(hpp, szp, &res,
 		 am.carriers,
 		 bld_unstable_uint(hpp, szp, curr_no),
@@ -2935,16 +4216,10 @@ info_calls(Allctr_t *allctr,
     if (print_to_p) {
 
 #define PRINT_CC_4(TO, TOA, NAME, CC)					\
-    if ((CC).giga_no == 0)						\
-	erts_print(TO, TOA, "%s calls: %b32u\n", NAME, CC.no);		\
-    else								\
-	erts_print(TO, TOA, "%s calls: %b32u%09lu\n", NAME, CC.giga_no, CC.no)
+	erts_print(TO, TOA, "%s calls: %b64u\n", NAME, CC)
 
 #define PRINT_CC_5(TO, TOA, PRFX, NAME, CC)				\
-    if ((CC).giga_no == 0)						\
-	erts_print(TO, TOA, "%s%s calls: %b32u\n",PRFX,NAME,CC.no);	\
-    else								\
-	erts_print(TO, TOA, "%s%s calls: %b32u%09lu\n",PRFX,NAME,CC.giga_no,CC.no)
+	erts_print(TO, TOA, "%s%s calls: %b64u\n",PRFX,NAME,CC)
 
 	char *prefix = allctr->name_prefix;
 	int to = *print_to_p;
@@ -2954,9 +4229,6 @@ info_calls(Allctr_t *allctr,
 	PRINT_CC_5(to, arg, prefix, "free",         allctr->calls.this_free);
 	PRINT_CC_5(to, arg, prefix, "realloc",      allctr->calls.this_realloc);
 
-	PRINT_CC_4(to, arg,         "sbmbc_alloc",  allctr->calls.sbmbc_alloc);
-	PRINT_CC_4(to, arg,         "sbmbc_free",   allctr->calls.sbmbc_free);
-
 #if HAVE_ERTS_MSEG
 	PRINT_CC_4(to, arg,         "mseg_alloc",   allctr->calls.mseg_alloc);
 	PRINT_CC_4(to, arg,         "mseg_dealloc", allctr->calls.mseg_dealloc);
@@ -2983,50 +4255,42 @@ info_calls(Allctr_t *allctr,
 
 	add_3tup(hpp, szp, &res,
 		 am.sys_realloc,
-		 bld_unstable_uint(hpp, szp, allctr->calls.sys_realloc.giga_no),
-		 bld_unstable_uint(hpp, szp, allctr->calls.sys_realloc.no));
+		 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_GIGA_VAL(allctr->calls.sys_realloc)),
+		 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_VAL(allctr->calls.sys_realloc)));
 	add_3tup(hpp, szp, &res,
 		 am.sys_free,
-		 bld_unstable_uint(hpp, szp, allctr->calls.sys_free.giga_no),
-		 bld_unstable_uint(hpp, szp, allctr->calls.sys_free.no));
+		 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_GIGA_VAL(allctr->calls.sys_free)),
+		 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_VAL(allctr->calls.sys_free)));
 	add_3tup(hpp, szp, &res,
 		 am.sys_alloc,
-		 bld_unstable_uint(hpp, szp, allctr->calls.sys_alloc.giga_no),
-		 bld_unstable_uint(hpp, szp, allctr->calls.sys_alloc.no));
+		 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_GIGA_VAL(allctr->calls.sys_alloc)),
+		 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_VAL(allctr->calls.sys_alloc)));
 #if HAVE_ERTS_MSEG
 	add_3tup(hpp, szp, &res,
 		 am.mseg_realloc,
-		 bld_unstable_uint(hpp, szp, allctr->calls.mseg_realloc.giga_no),
-		 bld_unstable_uint(hpp, szp, allctr->calls.mseg_realloc.no));
+		 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_GIGA_VAL(allctr->calls.mseg_realloc)),
+		 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_VAL(allctr->calls.mseg_realloc)));
 	add_3tup(hpp, szp, &res,
 		 am.mseg_dealloc,
-		 bld_unstable_uint(hpp, szp, allctr->calls.mseg_dealloc.giga_no),
-		 bld_unstable_uint(hpp, szp, allctr->calls.mseg_dealloc.no));
+		 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_GIGA_VAL(allctr->calls.mseg_dealloc)),
+		 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_VAL(allctr->calls.mseg_dealloc)));
 	add_3tup(hpp, szp, &res,
 		 am.mseg_alloc,
-		 bld_unstable_uint(hpp, szp, allctr->calls.mseg_alloc.giga_no),
-		 bld_unstable_uint(hpp, szp, allctr->calls.mseg_alloc.no));
+		 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_GIGA_VAL(allctr->calls.mseg_alloc)),
+		 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_VAL(allctr->calls.mseg_alloc)));
 #endif
 	add_3tup(hpp, szp, &res,
-		 am.sbmbc_free,
-		 bld_unstable_uint(hpp, szp, allctr->calls.sbmbc_free.giga_no),
-		 bld_unstable_uint(hpp, szp, allctr->calls.sbmbc_free.no));
-	add_3tup(hpp, szp, &res,
-		 am.sbmbc_alloc,
-		 bld_unstable_uint(hpp, szp, allctr->calls.sbmbc_alloc.giga_no),
-		 bld_unstable_uint(hpp, szp, allctr->calls.sbmbc_alloc.no));
-	add_3tup(hpp, szp, &res,
 		 allctr->name.realloc,
-		 bld_unstable_uint(hpp, szp, allctr->calls.this_realloc.giga_no),
-		 bld_unstable_uint(hpp, szp, allctr->calls.this_realloc.no));
+		 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_GIGA_VAL(allctr->calls.this_realloc)),
+		 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_VAL(allctr->calls.this_realloc)));
 	add_3tup(hpp, szp, &res,
 		 allctr->name.free,
-		 bld_unstable_uint(hpp, szp, allctr->calls.this_free.giga_no),
-		 bld_unstable_uint(hpp, szp, allctr->calls.this_free.no));
+		 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_GIGA_VAL(allctr->calls.this_free)),
+		 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_VAL(allctr->calls.this_free)));
 	add_3tup(hpp, szp, &res,
 		 allctr->name.alloc,
-		 bld_unstable_uint(hpp, szp, allctr->calls.this_alloc.giga_no),
-		 bld_unstable_uint(hpp, szp, allctr->calls.this_alloc.no));
+		 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_GIGA_VAL(allctr->calls.this_alloc)),
+		 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_VAL(allctr->calls.this_alloc)));
     }
 
     return res;
@@ -3040,6 +4304,7 @@ info_options(Allctr_t *allctr,
 	     Uint *szp)
 {
     Eterm res = THE_NON_VALUE;
+    int acul;
 
     if (!allctr) {
 	if (print_to_p)
@@ -3051,6 +4316,12 @@ info_options(Allctr_t *allctr,
 	return res;
     }
 
+#ifdef ERTS_SMP
+    acul = allctr->cpool.util_limit;
+#else
+    acul = 0;
+#endif
+
     if (print_to_p) {
 	char topt[21]; /* Enough for any 64-bit integer */
 	if (allctr->t)
@@ -3079,9 +4350,8 @@ info_options(Allctr_t *allctr,
 #endif
 		   "option lmbcs: %beu\n"
 		   "option smbcs: %beu\n"
-		   "option mbcgs: %beu\n"
-		   "option sbmbcs: %beu\n"
-		   "option sbmbct: %beu\n",
+		   "option mbcgs: %beu\n",
+		   "option acul: %d\n",
 		   topt,
 		   allctr->ramv ? "true" : "false",
 #if HALFWORD_HEAP
@@ -3102,8 +4372,7 @@ info_options(Allctr_t *allctr,
 		   allctr->largest_mbc_size,
 		   allctr->smallest_mbc_size,
 		   allctr->mbc_growth_stages,
-		   allctr->sbmbc_size,
-		   allctr->sbmbc_threshold);
+		   acul);
     }
 
     res = (*allctr->info_options)(allctr, "option ", print_to_p, print_to_arg,
@@ -3111,11 +4380,8 @@ info_options(Allctr_t *allctr,
 
     if (hpp || szp) {
 	add_2tup(hpp, szp, &res,
-		 am.sbmbct,
-		 bld_uint(hpp, szp, allctr->sbmbc_threshold));
-	add_2tup(hpp, szp, &res,
-		 am.sbmbcs,
-		 bld_uint(hpp, szp, allctr->sbmbc_size));
+		 am.acul,
+		 bld_uint(hpp, szp, (UWord) acul));
 	add_2tup(hpp, szp, &res,
 		 am.mbcgs,
 		 bld_uint(hpp, szp, allctr->mbc_growth_stages));
@@ -3261,13 +4527,17 @@ erts_alcu_info_options(Allctr_t *allctr,
 
 Eterm
 erts_alcu_sz_info(Allctr_t *allctr,
+		  int internal,
 		  int begin_max_period,
 		  int *print_to_p,
 		  void *print_to_arg,
 		  Uint **hpp,
 		  Uint *szp)
 {
-    Eterm res, sbmbcs, mbcs, sbcs, fix = THE_NON_VALUE;
+    Eterm res, mbcs, sbcs, fix = THE_NON_VALUE;
+#ifdef ERTS_SMP
+    Eterm mbcs_pool;
+#endif
 
     res  = THE_NON_VALUE;
 
@@ -3296,30 +4566,35 @@ erts_alcu_sz_info(Allctr_t *allctr,
 	= allctr->sbcs.curr.norm.mseg.no + allctr->sbcs.curr.norm.sys_alloc.no;
     allctr->sbcs.blocks.max.no = allctr->sbcs.max.no;
 
-    update_max_ever_values(&allctr->sbmbcs);
     update_max_ever_values(&allctr->mbcs);
     update_max_ever_values(&allctr->sbcs);
 
     if (allctr->fix)
-	fix = sz_info_fix(allctr, print_to_p, print_to_arg, hpp, szp);
-    sbmbcs = sz_info_carriers(allctr, &allctr->sbmbcs, "sbmbcs ", print_to_p,
-			      print_to_arg, hpp, szp);
+	fix = sz_info_fix(allctr, internal, print_to_p, print_to_arg, hpp, szp);
     mbcs = sz_info_carriers(allctr, &allctr->mbcs, "mbcs ", print_to_p,
 			    print_to_arg, hpp, szp);
+#ifdef ERTS_SMP
+    if (ERTS_ALC_IS_CPOOL_ENABLED(allctr))
+	mbcs_pool = info_cpool(allctr, 1, "mbcs_pool ", print_to_p,
+			       print_to_arg, hpp, szp);
+    else
+	mbcs_pool = THE_NON_VALUE; /* shut up annoying warning... */
+#endif
     sbcs = sz_info_carriers(allctr, &allctr->sbcs, "sbcs ", print_to_p,
 			    print_to_arg, hpp, szp);
 
     if (hpp || szp) {
 	res = NIL;
 	add_2tup(hpp, szp, &res, am.sbcs, sbcs);
+#ifdef ERTS_SMP
+	if (ERTS_ALC_IS_CPOOL_ENABLED(allctr))
+	    add_2tup(hpp, szp, &res, am.mbcs_pool, mbcs_pool);
+#endif
 	add_2tup(hpp, szp, &res, am.mbcs, mbcs);
-	add_2tup(hpp, szp, &res, am.sbmbcs, sbmbcs);
-	if (allctr->fix)
-	    add_2tup(hpp, szp, &res, am.fix_types, fix);
+	add_fix_types(allctr, internal, hpp, szp, &res, fix);
     }
 
     if (begin_max_period) {
-	reset_max_values(&allctr->sbmbcs);
 	reset_max_values(&allctr->mbcs);
 	reset_max_values(&allctr->sbcs);
     }
@@ -3338,13 +4613,17 @@ erts_alcu_sz_info(Allctr_t *allctr,
 
 Eterm
 erts_alcu_info(Allctr_t *allctr,
+	       int internal,
 	       int begin_max_period,
 	       int *print_to_p,
 	       void *print_to_arg,
 	       Uint **hpp,
 	       Uint *szp)
 {
-    Eterm res, sett, sbmbcs, mbcs, sbcs, calls, fix = THE_NON_VALUE;
+    Eterm res, sett, mbcs, sbcs, calls, fix = THE_NON_VALUE;
+#ifdef ERTS_SMP
+    Eterm mbcs_pool;
+#endif
 
     res  = THE_NON_VALUE;
 
@@ -3373,7 +4652,6 @@ erts_alcu_info(Allctr_t *allctr,
 	= allctr->sbcs.curr.norm.mseg.no + allctr->sbcs.curr.norm.sys_alloc.no;
     allctr->sbcs.blocks.max.no = allctr->sbcs.max.no;
 
-    update_max_ever_values(&allctr->sbmbcs);
     update_max_ever_values(&allctr->mbcs);
     update_max_ever_values(&allctr->sbcs);
 
@@ -3387,11 +4665,16 @@ erts_alcu_info(Allctr_t *allctr,
 
     sett = info_options(allctr, print_to_p, print_to_arg, hpp, szp);
     if (allctr->fix)
-	fix = sz_info_fix(allctr, print_to_p, print_to_arg, hpp, szp);
-    sbmbcs = info_carriers(allctr, &allctr->sbmbcs, "sbmbcs ", print_to_p,
-			   print_to_arg, hpp, szp);
+	fix = sz_info_fix(allctr, internal, print_to_p, print_to_arg, hpp, szp);
     mbcs = info_carriers(allctr, &allctr->mbcs, "mbcs ", print_to_p,
 			 print_to_arg, hpp, szp);
+#ifdef ERTS_SMP
+    if (ERTS_ALC_IS_CPOOL_ENABLED(allctr))
+	mbcs_pool = info_cpool(allctr, 0, "mbcs_pool ", print_to_p,
+			       print_to_arg, hpp, szp);
+    else
+	mbcs_pool = THE_NON_VALUE; /* shut up annoying warning... */
+#endif
     sbcs = info_carriers(allctr, &allctr->sbcs, "sbcs ", print_to_p,
 			 print_to_arg, hpp, szp);
     calls = info_calls(allctr, print_to_p, print_to_arg, hpp, szp);
@@ -3401,10 +4684,12 @@ erts_alcu_info(Allctr_t *allctr,
 
 	add_2tup(hpp, szp, &res, am.calls, calls);
 	add_2tup(hpp, szp, &res, am.sbcs, sbcs);
+#ifdef ERTS_SMP
+	if (ERTS_ALC_IS_CPOOL_ENABLED(allctr))
+	    add_2tup(hpp, szp, &res, am.mbcs_pool, mbcs_pool);
+#endif
 	add_2tup(hpp, szp, &res, am.mbcs, mbcs);
-	add_2tup(hpp, szp, &res, am.sbmbcs, sbmbcs);
-	if (allctr->fix)
-	    add_2tup(hpp, szp, &res, am.fix_types, fix);
+	add_fix_types(allctr, internal, hpp, szp, &res, fix);
 	add_2tup(hpp, szp, &res, am.options, sett);
 	add_3tup(hpp, szp, &res,
 		 am.versions,
@@ -3413,7 +4698,6 @@ erts_alcu_info(Allctr_t *allctr,
     }
 
     if (begin_max_period) {
-	reset_max_values(&allctr->sbmbcs);
 	reset_max_values(&allctr->mbcs);
 	reset_max_values(&allctr->sbcs);
     }
@@ -3441,22 +4725,37 @@ erts_alcu_current_size(Allctr_t *allctr, AllctrSize_t *size, ErtsAlcUFixInfo_t *
 
     size->carriers = allctr->mbcs.curr.norm.mseg.size;
     size->carriers += allctr->mbcs.curr.norm.sys_alloc.size;
-    size->carriers += allctr->sbmbcs.curr.small_block.size;
     size->carriers += allctr->sbcs.curr.norm.mseg.size;
     size->carriers += allctr->sbcs.curr.norm.sys_alloc.size;
 
     size->blocks = allctr->mbcs.blocks.curr.size;
-    size->blocks += allctr->sbmbcs.blocks.curr.size;
     size->blocks += allctr->sbcs.blocks.curr.size;
 
+#ifdef ERTS_SMP
+    if (ERTS_ALC_IS_CPOOL_ENABLED(allctr)) {
+	UWord csz, bsz;
+	cpool_read_stat(allctr, NULL, &csz, NULL, &bsz);
+	size->blocks += bsz;
+	size->carriers += csz;
+    }
+#endif
+
     if (fi) {
 	int ix;
 	for (ix = 0; ix < fisz; ix++) {
 	    if (allctr->fix) {
-		fi[ix].allocated += (allctr->fix[ix].type_size
-				     * allctr->fix[ix].allocated);
-		fi[ix].used += (allctr->fix[ix].type_size
-				* allctr->fix[ix].used);
+		if (ERTS_ALC_IS_CPOOL_ENABLED(allctr)) {
+		    fi[ix].allocated += (allctr->fix[ix].type_size
+					 * allctr->fix[ix].u.cpool.allocated);
+		    fi[ix].used += (allctr->fix[ix].type_size
+				    * allctr->fix[ix].u.cpool.used);
+		}
+		else {
+		    fi[ix].allocated += (allctr->fix[ix].type_size
+					 * allctr->fix[ix].u.nocpool.allocated);
+		    fi[ix].used += (allctr->fix[ix].type_size
+				    * allctr->fix[ix].u.nocpool.used);
+		}
 	    }
 	}
     }
@@ -3474,7 +4773,6 @@ do_erts_alcu_alloc(ErtsAlcType_t type, void *extra, Uint size)
 {
     Allctr_t *allctr = (Allctr_t *) extra; 
     void *res;
-    ErtsAlcFixList_t *fix;
 
     ASSERT(initialized);
 
@@ -3492,57 +4790,21 @@ do_erts_alcu_alloc(ErtsAlcType_t type, void *extra, Uint size)
 
     INC_CC(allctr->calls.this_alloc);
 
-    fix = allctr->fix;
-    if (fix) {
-	int ix = type - ERTS_ALC_N_MIN_A_FIXED_SIZE;
-	ASSERT((unsigned)ix < ERTS_ALC_NO_FIXED_SIZES);
-	ERTS_DBG_CHK_FIX_LIST(allctr, fix, ix, 1);
-	ASSERT(size <= fix[ix].type_size);
-	fix[ix].used++;
-	res = fix[ix].list;
-	if (res) {
-	    fix[ix].list_size--;
-	    fix[ix].list = *((void **) res);
-	    if (fix[ix].list && fix[ix].allocated > fix[ix].limit) {
-		void *p = fix[ix].list;
-		Block_t *blk;
-		fix[ix].list = *((void **) p);
-		fix[ix].list_size--;
-		blk = UMEM2BLK(p);
-		if (IS_SBC_BLK(blk))
-		    destroy_carrier(allctr, blk);
-		else
-		    mbc_free(allctr, p);
-		fix[ix].allocated--;
-	    }
-	    ERTS_DBG_CHK_FIX_LIST(allctr, fix, ix, 0);
-	    return res;
-	}
-	size = fix[ix].type_size;
-	if (fix[ix].limit < fix[ix].used)
-	    fix[ix].limit = fix[ix].used;
-	if (fix[ix].max_used < fix[ix].used)
-	    fix[ix].max_used = fix[ix].used;
-	fix[ix].allocated++;
+    if (allctr->fix) {
+	if (ERTS_ALC_IS_CPOOL_ENABLED(allctr))
+	    return fix_cpool_alloc(allctr, type, size);
+	else
+	    return fix_nocpool_alloc(allctr, type, size);
     }
 
     if (size >= allctr->sbc_threshold) {
 	Block_t *blk;
-#ifdef ERTS_SMP
-	if (allctr->dd.use)
-	    ERTS_ALCU_HANDLE_DD_IN_OP(allctr, 1);
-#endif
 	blk = create_carrier(allctr, size, CFLG_SBC);
 	res = blk ? BLK2UMEM(blk) : NULL;
     }
     else
 	res = mbc_alloc(allctr, size);
 
-    if (!res && fix) {
-	int ix = type - ERTS_ALC_N_MIN_A_FIXED_SIZE;
-	fix[ix].allocated--;
-	fix[ix].used--;
-    }
     return res;
 }
 
@@ -3611,9 +4873,22 @@ erts_alcu_alloc_thr_pref(ErtsAlcType_t type, void *extra, Uint size)
     if (pref_allctr->thread_safe)
 	erts_mtx_lock(&pref_allctr->mutex);
 
+#ifdef ERTS_SMP
+    ASSERT(pref_allctr->dd.use);
+    ERTS_ALCU_HANDLE_DD_IN_OP(pref_allctr, 1);
+#endif
+
     ERTS_ALCU_DBG_CHK_THR_ACCESS(pref_allctr);
 
     res = do_erts_alcu_alloc(type, pref_allctr, size);
+
+#ifdef ERTS_SMP
+    if (!res && ERTS_ALCU_HANDLE_DD_IN_OP(pref_allctr, 1)) {
+	/* Cleaned up a bit more; try one more time... */
+	res = do_erts_alcu_alloc(type, pref_allctr, size);
+    }
+#endif
+
     if (pref_allctr->thread_safe)
 	erts_mtx_unlock(&pref_allctr->mutex);
 
@@ -3630,9 +4905,9 @@ erts_alcu_alloc_thr_pref(ErtsAlcType_t type, void *extra, Uint size)
 /* ------------------------------------------------------------------------- */
 
 static ERTS_INLINE void
-do_erts_alcu_free(ErtsAlcType_t type, void *extra, void *p)
+do_erts_alcu_free(ErtsAlcType_t type, void *extra, void *p,
+		  Carrier_t **busy_pcrr_pp)
 {
-    int ix;
     Allctr_t *allctr = (Allctr_t *) extra; 
     ASSERT(initialized);
 
@@ -3644,57 +4919,28 @@ do_erts_alcu_free(ErtsAlcType_t type, void *extra, void *p)
     ERTS_ALCU_DBG_CHK_THR_ACCESS(allctr);
 
     if (p) {
-	ErtsAlcFixList_t *fix = allctr->fix;
-	Block_t *blk;
 
 	INC_CC(allctr->calls.this_free);
 
-	if (fix) {
-	    ix = type - ERTS_ALC_N_MIN_A_FIXED_SIZE;
-	    ERTS_DBG_CHK_FIX_LIST(allctr, fix, ix, 1);
-	    fix[ix].used--;
-	    if (fix[ix].allocated < fix[ix].limit
-		&& fix[ix].list_size < ERTS_ALCU_FIX_MAX_LIST_SZ) {
-		*((void **) p) = fix[ix].list;
-		fix[ix].list = p;
-		fix[ix].list_size++;
-		if (!allctr->fix_shrink_scheduled) {
-		    allctr->fix_shrink_scheduled = 1;
-		    erts_set_aux_work_timeout(
-			allctr->ix,
-			(ERTS_SSI_AUX_WORK_FIX_ALLOC_LOWER_LIM
-			 | ERTS_SSI_AUX_WORK_FIX_ALLOC_DEALLOC),
-			1);
-		}
-		ERTS_DBG_CHK_FIX_LIST(allctr, fix, ix, 0);
-		return;
-	    }
-	    fix[ix].allocated--;
-	    if (fix[ix].list && fix[ix].allocated > fix[ix].limit) {
-		blk = UMEM2BLK(p);
-		if (IS_SBC_BLK(blk))
-		    destroy_carrier(allctr, blk);
-		else
-		    mbc_free(allctr, p);
-		p = fix[ix].list;
-		fix[ix].list = *((void **) p);
-		fix[ix].list_size--;
-		fix[ix].allocated--;
-	    }
+	if (allctr->fix) {
+	    if (ERTS_ALC_IS_CPOOL_ENABLED(allctr))
+		fix_cpool_free(allctr, type, p, busy_pcrr_pp);
+	    else
+		fix_nocpool_free(allctr, type, p);
+	}
+	else {
+	    Block_t *blk = UMEM2BLK(p);
+	    if (IS_SBC_BLK(blk))
+		destroy_carrier(allctr, blk, NULL);
+	    else
+		mbc_free(allctr, p, busy_pcrr_pp);
 	}
-
-	blk = UMEM2BLK(p);
-	if (IS_SBC_BLK(blk))
-	    destroy_carrier(allctr, blk);
-	else
-	    mbc_free(allctr, p);
-	ERTS_DBG_CHK_FIX_LIST(allctr, fix, ix, 0);
     }
 }
 
 void erts_alcu_free(ErtsAlcType_t type, void *extra, void *p)
 {
-    do_erts_alcu_free(type, extra, p);
+    do_erts_alcu_free(type, extra, p, NULL);
 }
 
 #ifdef USE_THREADS
@@ -3704,7 +4950,7 @@ erts_alcu_free_ts(ErtsAlcType_t type, void *extra, void *p)
 {
     Allctr_t *allctr = (Allctr_t *) extra;
     erts_mtx_lock(&allctr->mutex);
-    do_erts_alcu_free(type, extra, p);
+    do_erts_alcu_free(type, extra, p, NULL);
     erts_mtx_unlock(&allctr->mutex);
 }
 
@@ -3726,7 +4972,7 @@ erts_alcu_free_thr_spec(ErtsAlcType_t type, void *extra, void *p)
     if (allctr->thread_safe)
 	erts_mtx_lock(&allctr->mutex);
 
-    do_erts_alcu_free(type, allctr, p);
+    do_erts_alcu_free(type, allctr, p, NULL);
 
     if (allctr->thread_safe)
 	erts_mtx_unlock(&allctr->mutex);
@@ -3736,10 +4982,12 @@ void
 erts_alcu_free_thr_pref(ErtsAlcType_t type, void *extra, void *p)
 {
     if (p) {
+	Carrier_t *busy_pcrr_p;
 	Allctr_t *pref_allctr, *used_allctr;
 
 	pref_allctr = get_pref_allctr(extra);
-	used_allctr = get_used_allctr(extra, p, NULL);
+	used_allctr = get_used_allctr(pref_allctr, ERTS_ALC_TS_PREF_LOCK_IF_USED,
+				      p, NULL, &busy_pcrr_p);
 	if (pref_allctr != used_allctr)
 	    enqueue_dealloc_other_instance(type,
 					   used_allctr,
@@ -3747,12 +4995,11 @@ erts_alcu_free_thr_pref(ErtsAlcType_t type, void *extra, void *p)
 					   (used_allctr->dd.ix
 					    - pref_allctr->dd.ix));
 	else {
-	    if (used_allctr->thread_safe)
-		erts_mtx_lock(&used_allctr->mutex);
 	    ERTS_ALCU_DBG_CHK_THR_ACCESS(used_allctr);
-	    do_erts_alcu_free(type, used_allctr, p);
-	    if (used_allctr->thread_safe)
-		erts_mtx_unlock(&used_allctr->mutex);
+	    do_erts_alcu_free(type, used_allctr, p, &busy_pcrr_p);
+	    clear_busy_pool_carrier(used_allctr, busy_pcrr_p);
+	    if (pref_allctr->thread_safe)
+		erts_mtx_unlock(&pref_allctr->mutex);
 	}
     }
 }
@@ -3768,7 +5015,8 @@ do_erts_alcu_realloc(ErtsAlcType_t type,
 		     void *extra,
 		     void *p,
 		     Uint size,
-		     Uint32 alcu_flgs)
+		     Uint32 alcu_flgs,
+		     Carrier_t **busy_pcrr_pp)
 {
     Allctr_t *allctr = (Allctr_t *) extra; 
     Block_t *blk;
@@ -3793,7 +5041,7 @@ do_erts_alcu_realloc(ErtsAlcType_t type,
 #if ALLOC_ZERO_EQ_NULL
     if (!size) {
 	ASSERT(p);
-	do_erts_alcu_free(type, extra, p);
+	do_erts_alcu_free(type, extra, p, busy_pcrr_pp);
 	INC_CC(allctr->calls.this_realloc);
 	DEC_CC(allctr->calls.this_free);
 	return NULL;
@@ -3804,32 +5052,9 @@ do_erts_alcu_realloc(ErtsAlcType_t type,
     
     blk = UMEM2BLK(p);
 
-    if (allctr->sbmbc_threshold > 0) {
-	Uint old_sz, new_sz, lim;
-	lim = allctr->sbmbc_threshold;
-	old_sz = BLK_SZ(blk);
-	new_sz = UMEMSZ2BLKSZ(allctr, size);
-	if ((old_sz < lim && lim <= new_sz)
-	    || (new_sz < lim && lim <= old_sz)) {
-	    /* *Need* to move it... */
-
-	    INC_CC(allctr->calls.this_realloc);
-	    res = do_erts_alcu_alloc(type, extra, size);
-	    DEC_CC(allctr->calls.this_alloc);
-
-	    sys_memcpy(res, p, MIN(size, old_sz - ABLK_HDR_SZ));
-
-	    do_erts_alcu_free(type, extra, p);
-	    DEC_CC(allctr->calls.this_free);
-	    return res;
-	}
-	if (old_sz < lim)
-	    alcu_flgs |= ERTS_ALCU_FLG_SBMBC;
-    }
-
     if (size < allctr->sbc_threshold) {
 	if (IS_MBC_BLK(blk))
-	    res = mbc_realloc(allctr, p, size, alcu_flgs);
+	    res = mbc_realloc(allctr, p, size, alcu_flgs, busy_pcrr_pp);
 	else {
 	    Uint used_sz = SBC_HEADER_SIZE + ABLK_HDR_SZ + size;
 	    Uint crr_sz;
@@ -3868,16 +5093,12 @@ do_erts_alcu_realloc(ErtsAlcType_t type,
 		sys_memcpy((void*) res,
 			   (void*) p,
 			   MIN(SBC_BLK_SZ(blk) - ABLK_HDR_SZ, size));
-		destroy_carrier(allctr, blk);
+		destroy_carrier(allctr, blk, NULL);
 	    }
 	}
     }
     else {
 	Block_t *new_blk;
-#ifdef ERTS_SMP
-	if (allctr->dd.use)
-	    ERTS_ALCU_HANDLE_DD_IN_OP(allctr, 1);
-#endif
 	if(IS_SBC_BLK(blk)) {
 	do_carrier_resize:
 #if HALFWORD_HEAP
@@ -3896,7 +5117,7 @@ do_erts_alcu_realloc(ErtsAlcType_t type,
 		sys_memcpy((void *) res,
 			   (void *) p,
 			   MIN(MBC_ABLK_SZ(blk) - ABLK_HDR_SZ, size));
-		mbc_free(allctr, p);
+		mbc_free(allctr, p, busy_pcrr_pp);
 	    }
 	    else
 		res = NULL;
@@ -3910,7 +5131,7 @@ void *
 erts_alcu_realloc(ErtsAlcType_t type, void *extra, void *p, Uint size)
 {
     void *res;
-    res = do_erts_alcu_realloc(type, extra, p, size, 0);
+    res = do_erts_alcu_realloc(type, extra, p, size, 0, NULL);
     DEBUG_CHECK_ALIGNMENT(res);
     return res;
 }
@@ -3931,7 +5152,7 @@ erts_alcu_realloc_mv(ErtsAlcType_t type, void *extra, void *p, Uint size)
 	if (cpy_size > size)
 	    cpy_size = size;
 	sys_memcpy(res, p, cpy_size);
-	do_erts_alcu_free(type, extra, p);
+	do_erts_alcu_free(type, extra, p, NULL);
     }
     DEBUG_CHECK_ALIGNMENT(res);
     return res;
@@ -3946,7 +5167,7 @@ erts_alcu_realloc_ts(ErtsAlcType_t type, void *extra, void *ptr, Uint size)
     Allctr_t *allctr = (Allctr_t *) extra;
     void *res;
     erts_mtx_lock(&allctr->mutex);
-    res = do_erts_alcu_realloc(type, extra, ptr, size, 0);
+    res = do_erts_alcu_realloc(type, extra, ptr, size, 0, NULL);
     erts_mtx_unlock(&allctr->mutex);
     DEBUG_CHECK_ALIGNMENT(res);
     return res;
@@ -3970,7 +5191,7 @@ erts_alcu_realloc_mv_ts(ErtsAlcType_t type, void *extra, void *p, Uint size)
 	if (cpy_size > size)
 	    cpy_size = size;
 	sys_memcpy(res, p, cpy_size);
-	do_erts_alcu_free(type, extra, p);
+	do_erts_alcu_free(type, extra, p, NULL);
     }
     erts_mtx_unlock(&allctr->mutex);
     DEBUG_CHECK_ALIGNMENT(res);
@@ -3997,7 +5218,7 @@ erts_alcu_realloc_thr_spec(ErtsAlcType_t type, void *extra,
     if (allctr->thread_safe)
 	erts_mtx_lock(&allctr->mutex);
 
-    res = do_erts_alcu_realloc(type, allctr, ptr, size, 0);
+    res = do_erts_alcu_realloc(type, allctr, ptr, size, 0, NULL);
 
     if (allctr->thread_safe)
 	erts_mtx_unlock(&allctr->mutex);
@@ -4040,7 +5261,7 @@ erts_alcu_realloc_mv_thr_spec(ErtsAlcType_t type, void *extra,
 	if (cpy_size > size)
 	    cpy_size = size;
 	sys_memcpy(res, ptr, cpy_size);
-	do_erts_alcu_free(type, allctr, ptr);
+	do_erts_alcu_free(type, allctr, ptr, NULL);
 	if (allctr->thread_safe)
 	    erts_mtx_unlock(&allctr->mutex);
     }
@@ -4057,40 +5278,64 @@ realloc_thr_pref(ErtsAlcType_t type, void *extra, void *p, Uint size,
     void *res;
     Allctr_t *pref_allctr, *used_allctr;
     UWord old_user_size;
+    Carrier_t *busy_pcrr_p;
+#ifdef ERTS_SMP
+    int retried;
+#endif
 
     if (!p)
 	return erts_alcu_alloc_thr_pref(type, extra, size);
 
     pref_allctr = get_pref_allctr(extra);
-    used_allctr = get_used_allctr(extra, p, &old_user_size);
+
+    if (pref_allctr->thread_safe)
+	erts_mtx_lock(&pref_allctr->mutex);
+
+#ifdef ERTS_SMP
+    ASSERT(pref_allctr->dd.use);
+    ERTS_ALCU_HANDLE_DD_IN_OP(pref_allctr, 1);
+    retried = 0;
+restart:
+#endif
+
+    used_allctr = get_used_allctr(pref_allctr, ERTS_ALC_TS_PREF_LOCK_NO,
+				  p, &old_user_size, &busy_pcrr_p);
 
     ASSERT(used_allctr && pref_allctr);
 
     if (!force_move && used_allctr == pref_allctr) {
-	if (used_allctr->thread_safe)
-	    erts_mtx_lock(&used_allctr->mutex);
 	ERTS_ALCU_DBG_CHK_THR_ACCESS(used_allctr);
 	res = do_erts_alcu_realloc(type,
 				   used_allctr,
 				   p,
 				   size,
-				   0);
-	if (used_allctr->thread_safe)
-	    erts_mtx_unlock(&used_allctr->mutex);
+				   0,
+				   &busy_pcrr_p);
+	clear_busy_pool_carrier(used_allctr, busy_pcrr_p);
+#ifdef ERTS_SMP
+	if (!res && !retried && ERTS_ALCU_HANDLE_DD_IN_OP(pref_allctr, 1)) {
+	    /* Cleaned up a bit more; try one more time... */
+	    retried = 1;
+	    goto restart;
+	}
+#endif	    
+	if (pref_allctr->thread_safe)
+	    erts_mtx_unlock(&pref_allctr->mutex);
     }
     else {
-	if (pref_allctr->thread_safe)
-	    erts_mtx_lock(&pref_allctr->mutex);
 	res = do_erts_alcu_alloc(type, pref_allctr, size);
-	if (pref_allctr->thread_safe && used_allctr != pref_allctr) {
-	    erts_mtx_unlock(&pref_allctr->mutex);
-	}
-	if (res) {
-	    DEBUG_CHECK_ALIGNMENT(res);
+	if (!res)
+	    goto unlock_ts_return;
+	else {
 
-	    sys_memcpy(res, p, MIN(size,old_user_size));
+	    DEBUG_CHECK_ALIGNMENT(res);
 
 	    if (used_allctr != pref_allctr) {
+		if (pref_allctr->thread_safe)
+		    erts_mtx_unlock(&pref_allctr->mutex);
+
+		sys_memcpy(res, p, MIN(size, old_user_size));
+
 		enqueue_dealloc_other_instance(type,
 					       used_allctr,
 					       p,
@@ -4098,8 +5343,14 @@ realloc_thr_pref(ErtsAlcType_t type, void *extra, void *p, Uint size,
 						- pref_allctr->dd.ix));
 	    }
 	    else {
-		do_erts_alcu_free(type, used_allctr, p);
+
+		sys_memcpy(res, p, MIN(size, old_user_size));
+
+		do_erts_alcu_free(type, used_allctr, p, &busy_pcrr_p);
 		ASSERT(pref_allctr == used_allctr);
+		clear_busy_pool_carrier(used_allctr, busy_pcrr_p);
+
+	    unlock_ts_return:
 		if (pref_allctr->thread_safe)
 		    erts_mtx_unlock(&pref_allctr->mutex);
 	    }
@@ -4213,6 +5464,17 @@ erts_alcu_start(Allctr_t *allctr, AllctrInit_t *init)
 	if (sz > allctr->min_block_size)
 	    allctr->min_block_size = sz;
     }
+
+    allctr->cpool.dc_list.first = NULL;
+    allctr->cpool.dc_list.last = NULL;
+    allctr->cpool.abandon_limit = 0;
+    allctr->cpool.disable_abandon = 0;
+    erts_atomic_init_nob(&allctr->cpool.stat.blocks_size, 0);
+    erts_atomic_init_nob(&allctr->cpool.stat.no_blocks, 0);
+    erts_atomic_init_nob(&allctr->cpool.stat.carriers_size, 0);
+    erts_atomic_init_nob(&allctr->cpool.stat.no_carriers, 0);
+    allctr->cpool.check_limit_count = ERTS_ALC_CPOOL_CHECK_LIMIT_COUNT;
+    allctr->cpool.util_limit = init->acul;
 #endif
 
     allctr->sbc_threshold		= init->sbct;
@@ -4232,27 +5494,6 @@ erts_alcu_start(Allctr_t *allctr, AllctrInit_t *init)
     }
 #endif
 
-
-
-    allctr->sbmbc_threshold		= init->sbmbct;
-
-    if (!erts_have_sbmbc_alloc
-	|| ERTS_IS_SBMBC_ALLOCATOR_NO__(allctr->alloc_no))
-	allctr->sbmbc_threshold = 0;
-
-    if (!allctr->sbmbc_threshold)
-	allctr->sbmbc_size = 0;
-    else {
-	Uint min_size;
-	allctr->sbmbc_size = init->sbmbcs;
-	min_size = allctr->sbmbc_threshold;
-	min_size += allctr->min_block_size;
-	min_size += MBC_HEADER_SIZE(allctr);
-	if (allctr->sbmbc_size < min_size)
-	    allctr->sbmbc_size = min_size;
-    }
-
-
 #if HAVE_ERTS_MSEG
     if (allctr->mseg_opt.abs_shrink_th > ~((UWord) 0) / 100)
 	allctr->mseg_opt.abs_shrink_th = ~((UWord) 0) / 100;
@@ -4264,16 +5505,12 @@ erts_alcu_start(Allctr_t *allctr, AllctrInit_t *init)
 	
 #ifdef ERTS_ENABLE_LOCK_COUNT
 	erts_mtx_init_x_opt(&allctr->mutex,
-			    ERTS_IS_SBMBC_ALLOCATOR_NO__(allctr->alloc_no)
-			    ? "sbmbc_alloc"
-			    : "alcu_allocator",
+			    "alcu_allocator",
 			    make_small(allctr->alloc_no),
 			    ERTS_LCNT_LT_ALLOC);
 #else
 	erts_mtx_init_x(&allctr->mutex,
-			ERTS_IS_SBMBC_ALLOCATOR_NO__(allctr->alloc_no)
-			? "sbmbc_alloc"
-			: "alcu_allocator",
+			"alcu_allocator",
 			make_small(allctr->alloc_no));
 #endif /*ERTS_ENABLE_LOCK_COUNT*/
 	
@@ -4292,6 +5529,8 @@ erts_alcu_start(Allctr_t *allctr, AllctrInit_t *init)
     if (!allctr->get_next_mbc_size)
 	allctr->get_next_mbc_size = get_next_mbc_size;
 
+    if (allctr->mbc_header_size < sizeof(Carrier_t))
+	goto error;
 #ifdef ERTS_SMP
     allctr->dd.use = 0;
     if (init->tpref) {
@@ -4300,6 +5539,9 @@ erts_alcu_start(Allctr_t *allctr, AllctrInit_t *init)
 	allctr->dd.ix = init->ix;
     }
 #endif
+    allctr->mbc_header_size = (UNIT_CEILING(allctr->mbc_header_size
+					    + ABLK_HDR_SZ)
+			       - ABLK_HDR_SZ);
 
     if (allctr->main_carrier_size) {
 	Block_t *blk;
@@ -4308,6 +5550,7 @@ erts_alcu_start(Allctr_t *allctr, AllctrInit_t *init)
 			     allctr->main_carrier_size,
 			     CFLG_MBC
 			     | CFLG_FORCE_SIZE
+			     | CFLG_NO_CPOOL
 #if !HALFWORD_HEAP && !HAVE_SUPER_ALIGNED_MB_CARRIERS
 			     | CFLG_FORCE_SYS_ALLOC
 #endif
@@ -4315,7 +5558,7 @@ erts_alcu_start(Allctr_t *allctr, AllctrInit_t *init)
 	if (!blk)
 	    goto error;
 
-	(*allctr->link_free_block)(allctr, blk, 0);
+	(*allctr->link_free_block)(allctr, blk);
 
 	HARD_CHECK_BLK_CARRIER(allctr, blk);
 
@@ -4326,16 +5569,24 @@ erts_alcu_start(Allctr_t *allctr, AllctrInit_t *init)
 	allctr->fix = init->fix;
 	allctr->fix_shrink_scheduled = 0;
 	for (i = 0; i < ERTS_ALC_NO_FIXED_SIZES; i++) {
-	    allctr->fix[i].max_used = 0;
-	    allctr->fix[i].limit = 0;
 	    allctr->fix[i].type_size = init->fix_type_size[i];
 	    allctr->fix[i].list_size = 0;
 	    allctr->fix[i].list = NULL;
-	    allctr->fix[i].allocated = 0;
-	    allctr->fix[i].used = 0;
 #ifdef ERTS_SMP
 	    ASSERT(allctr->fix[i].type_size >= sizeof(ErtsAllctrFixDDBlock_t));
 #endif
+	    if (ERTS_ALC_IS_CPOOL_ENABLED(allctr)) {
+		allctr->fix[i].u.cpool.min_list_size = 0;
+		allctr->fix[i].u.cpool.shrink_list = 0;
+		allctr->fix[i].u.cpool.allocated = 0;
+		allctr->fix[i].u.cpool.used = 0;
+	    }
+	    else {
+		allctr->fix[i].u.nocpool.max_used = 0;
+		allctr->fix[i].u.nocpool.limit = 0;
+		allctr->fix[i].u.nocpool.allocated = 0;
+		allctr->fix[i].u.nocpool.used = 0;
+	    }
 	}
     }
 
@@ -4360,11 +5611,9 @@ erts_alcu_stop(Allctr_t *allctr)
     allctr->stopped = 1;
 
     while (allctr->sbc_list.first)
-	destroy_carrier(allctr, SBC2BLK(allctr, allctr->sbc_list.first));
+	destroy_carrier(allctr, SBC2BLK(allctr, allctr->sbc_list.first), NULL);
     while (allctr->mbc_list.first)
-	destroy_carrier(allctr, MBC_TO_FIRST_BLK(allctr, allctr->mbc_list.first));
-    while (allctr->sbmbc_list.first)
-	destroy_sbmbc(allctr, MBC_TO_FIRST_BLK(allctr, allctr->sbmbc_list.first));
+	destroy_carrier(allctr, MBC_TO_FIRST_BLK(allctr, allctr->mbc_list.first), NULL);
 
 #ifdef USE_THREADS
     if (allctr->thread_safe)
@@ -4378,6 +5627,14 @@ erts_alcu_stop(Allctr_t *allctr)
 void
 erts_alcu_init(AlcUInit_t *init)
 {
+#ifdef ERTS_SMP
+    int i;
+    for (i = 0; i <= ERTS_ALC_A_MAX; i++) {
+	ErtsAlcCPoolData_t *sentinel = &carrier_pool[i].sentinel;
+	erts_atomic_init_nob(&sentinel->next, (erts_aint_t) sentinel);
+	erts_atomic_init_nob(&sentinel->prev, (erts_aint_t) sentinel);
+    }
+#endif
     ASSERT(SBC_BLK_SZ_MASK == MBC_FBLK_SZ_MASK); /* see BLK_SZ */
 #if HAVE_ERTS_MSEG
     ASSERT(erts_mseg_unit_size() == MSEG_UNIT_SZ);
@@ -4440,8 +5697,35 @@ erts_alcu_test(UWord op, UWord a1, UWord a2)
     case 0x019:	return (UWord) PREV_BLK((Block_t *) a1);
     case 0x01a: return (UWord) IS_MBC_FIRST_BLK((Allctr_t*)a1, (Block_t *) a2);
     case 0x01b: return (UWord) sizeof(Unit_t);
+    case 0x01c: return (unsigned long) BLK_TO_MBC((Block_t*) a1);
+    case 0x01d: ((Allctr_t*) a1)->add_mbc((Allctr_t*)a1, (Carrier_t*)a2); break;
+    case 0x01e: ((Allctr_t*) a1)->remove_mbc((Allctr_t*)a1, (Carrier_t*)a2); break;
+#ifdef ERTS_SMP
+    case 0x01f: return (UWord) sizeof(ErtsAlcCrrPool_t);
+    case 0x020:
+	SET_CARRIER_HDR((Carrier_t *) a2, 0, SCH_SYS_ALLOC|SCH_MBC, (Allctr_t *) a1);
+	cpool_init_carrier_data((Allctr_t *) a1, (Carrier_t *) a2);
+	return (UWord) a2;
+    case 0x021:
+	cpool_insert((Allctr_t *) a1, (Carrier_t *) a2);
+	return (UWord) a2;
+    case 0x022:
+	cpool_delete((Allctr_t *) a1, (Allctr_t *) a1, (Carrier_t *) a2);
+	return (UWord) a2;
+    case 0x023: return (UWord) cpool_is_empty((Allctr_t *) a1);
+    case 0x024: return (UWord) cpool_dbg_is_in_pool((Allctr_t *) a1, (Carrier_t *) a2);
+#else
+    case 0x01f: return (UWord) 0;
+    case 0x020: return (UWord) 0;
+    case 0x021: return (UWord) 0;
+    case 0x022: return (UWord) 0;
+    case 0x023: return (UWord) 0;
+    case 0x024: return (UWord) 0;
+#endif
+
     default:	ASSERT(0); return ~((UWord) 0);
     }
+    return 0;
 }
 
 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *\
@@ -4449,6 +5733,20 @@ erts_alcu_test(UWord op, UWord a1, UWord a2)
 \*                                                                           */
 
 void
+erts_alcu_assert_failed(char* expr, char* file, int line, char *func)
+{
+    fflush(stdout);
+    fprintf(stderr, "%s:%d:%s(): Assertion failed: %s\n",
+	    file, line, func, expr);
+    fflush(stderr);
+#if defined(__WIN__) || defined(__WIN32__)
+    DebugBreak();
+#else
+    abort();
+#endif
+}
+
+void
 erts_alcu_verify_unused(Allctr_t *allctr)
 {
     UWord no;
@@ -4456,12 +5754,10 @@ erts_alcu_verify_unused(Allctr_t *allctr)
     no = allctr->sbcs.curr.norm.mseg.no;
     no += allctr->sbcs.curr.norm.sys_alloc.no;
     no += allctr->mbcs.blocks.curr.no;
-    no += allctr->sbmbcs.blocks.curr.no;
 
     if (no) {
 	UWord sz = allctr->sbcs.blocks.curr.size;
 	sz += allctr->mbcs.blocks.curr.size;
-	sz += allctr->sbmbcs.blocks.curr.size;
 	erl_exit(ERTS_ABORT_EXIT,
 		 "%salloc() used when expected to be unused!\n"
 		 "Total amount of blocks allocated: %bpu\n"
@@ -4595,7 +5891,7 @@ check_blk_carrier(Allctr_t *allctr, Block_t *iblk)
 	cl = &allctr->mbc_list;
     }
 
-#if 0 /* FIXIT sbmbc */
+#ifdef DEBUG
     if (cl->first == crr) {
 	ASSERT(!crr->prev);
     }
diff --git a/erts/emulator/beam/erl_alloc_util.h b/erts/emulator/beam/erl_alloc_util.h
index 4773598561..5e52b9b733 100644
--- a/erts/emulator/beam/erl_alloc_util.h
+++ b/erts/emulator/beam/erl_alloc_util.h
@@ -55,8 +55,7 @@ typedef struct {
     UWord lmbcs;
     UWord smbcs;
     UWord mbcgs;
-    UWord sbmbct;
-    UWord sbmbcs;
+    int acul;
 
     void *fix;
     size_t *fix_type_size;
@@ -100,8 +99,7 @@ typedef struct {
     10*1024*1024,	/* (bytes)  lmbcs:  largest mbc size             */\
     1024*1024,		/* (bytes)  smbcs:  smallest mbc size            */\
     10,			/* (amount) mbcgs:  mbc growth stages            */\
-    256,	       	/* (bytes)  sbmbct:  small block mbc threshold   */\
-    8*1024,		/* (bytes)  sbmbcs:  small block mbc size        */ \
+    0,			/* (%)      acul:  abandon carrier utilization limit */\
     /* --- Data not options -------------------------------------------- */\
     NULL,		/* (ptr)    fix                                  */\
     NULL		/* (ptr)    fix_type_size                        */\
@@ -134,8 +132,7 @@ typedef struct {
     1024*1024,		/* (bytes)  lmbcs:  largest mbc size             */\
     128*1024,		/* (bytes)  smbcs:  smallest mbc size            */\
     10,			/* (amount) mbcgs:  mbc growth stages            */\
-    256,	       	/* (bytes)  sbmbct:  small block mbc threshold   */\
-    8*1024,		/* (bytes)  sbmbcs:  small block mbc size        */ \
+    0,			/* (%)      acul:  abandon carrier utilization limit */\
     /* --- Data not options -------------------------------------------- */\
     NULL,		/* (ptr)    fix                                  */\
     NULL		/* (ptr)    fix_type_size                        */\
@@ -165,8 +162,8 @@ void	erts_alcu_free_thr_pref(ErtsAlcType_t, void *, void *);
 #endif
 Eterm	erts_alcu_au_info_options(int *, void *, Uint **, Uint *);
 Eterm	erts_alcu_info_options(Allctr_t *, int *, void *, Uint **, Uint *);
-Eterm	erts_alcu_sz_info(Allctr_t *, int, int *, void *, Uint **, Uint *);
-Eterm	erts_alcu_info(Allctr_t *, int, int *, void *, Uint **, Uint *);
+Eterm	erts_alcu_sz_info(Allctr_t *, int, int, int *, void *, Uint **, Uint *);
+Eterm	erts_alcu_info(Allctr_t *, int, int, int *, void *, Uint **, Uint *);
 void	erts_alcu_init(AlcUInit_t *);
 void    erts_alcu_current_size(Allctr_t *, AllctrSize_t *,
 			       ErtsAlcUFixInfo_t *, int);
@@ -181,7 +178,6 @@ erts_aint32_t erts_alcu_fix_alloc_shrink(Allctr_t *, erts_aint32_t);
 #define ERL_ALLOC_UTIL_IMPL__
 
 #define ERTS_ALCU_FLG_FAIL_REALLOC_MOVE		(((Uint32) 1) << 0)
-#define ERTS_ALCU_FLG_SBMBC			(((Uint32) 1) << 1)
 
 #ifdef USE_THREADS
 #define ERL_THREADS_EMU_INTERNAL__
@@ -221,8 +217,15 @@ erts_aint32_t erts_alcu_fix_alloc_shrink(Allctr_t *, erts_aint32_t);
 #define MBC_FBLK_SZ_MASK        UNIT_MASK
 #define CARRIER_SZ_MASK         UNIT_MASK
 
-
 #if HAVE_ERTS_MSEG
+
+#  define MSEG_UNIT_SHIFT         MSEG_ALIGN_BITS
+#  define MSEG_UNIT_SZ            (1 << MSEG_UNIT_SHIFT)
+#  define MSEG_UNIT_MASK		((~(UWord)0) << MSEG_UNIT_SHIFT)
+
+#  define MSEG_UNIT_FLOOR(X)	((X) & MSEG_UNIT_MASK)
+#  define MSEG_UNIT_CEILING(X)	MSEG_UNIT_FLOOR((X) + ~MSEG_UNIT_MASK)
+
 #  ifdef ARCH_64 
 #    define MBC_ABLK_OFFSET_BITS   24
 #  elif HAVE_SUPER_ALIGNED_MB_CARRIERS
@@ -238,10 +241,8 @@ erts_aint32_t erts_alcu_fix_alloc_shrink(Allctr_t *, erts_aint32_t);
 #  define MBC_ABLK_OFFSET_SHIFT  (sizeof(UWord)*8 - MBC_ABLK_OFFSET_BITS)
 #  define MBC_ABLK_OFFSET_MASK   (~((UWord)0) << MBC_ABLK_OFFSET_SHIFT)
 #  define MBC_ABLK_SZ_MASK	(~MBC_ABLK_OFFSET_MASK & ~FLG_MASK)
-#  define HAVE_ERTS_SBMBC 0
 #else
 #  define MBC_ABLK_SZ_MASK	(~FLG_MASK)
-#  define HAVE_ERTS_SBMBC 1
 #endif
 
 #define MBC_ABLK_SZ(B) (ASSERT_EXPR(!is_sbc_blk(B)), (B)->bhdr & MBC_ABLK_SZ_MASK)
@@ -251,18 +252,37 @@ erts_aint32_t erts_alcu_fix_alloc_shrink(Allctr_t *, erts_aint32_t);
 #define CARRIER_SZ(C) \
   ((C)->chdr & CARRIER_SZ_MASK)
 
-extern int erts_have_sbmbc_alloc;
-
 typedef union {char c[ERTS_ALLOC_ALIGN_BYTES]; long l; double d;} Unit_t;
 
+#ifdef ERTS_SMP
+
+typedef struct {
+    erts_atomic_t next;
+    erts_atomic_t prev;
+    Allctr_t *orig_allctr;
+    ErtsThrPrgrVal thr_prgr;
+    erts_atomic_t max_size;
+    UWord abandon_limit;
+    UWord blocks;
+    UWord blocks_size;
+} ErtsAlcCPoolData_t;
+
+#endif
+
 typedef struct Carrier_t_ Carrier_t;
 struct Carrier_t_ {
     UWord chdr;
     Carrier_t *next;
     Carrier_t *prev;
-    Allctr_t  *allctr;
+    erts_smp_atomic_t allctr;
+#ifdef ERTS_SMP
+    ErtsAlcCPoolData_t cpool; /* Overwritten by block if sbc */
+#endif
 };
 
+#define ERTS_ALC_CARRIER_TO_ALLCTR(C) \
+  ((Allctr_t *) (erts_smp_atomic_read_nob(&(C)->allctr) & ~FLG_MASK))
+
 typedef struct {
     Carrier_t *first;
     Carrier_t *last;
@@ -280,12 +300,46 @@ typedef struct {
 #endif
 } Block_t;
 
+#define THIS_FREE_BLK_HDR_FLG 	(((UWord) 1) << 0)
+#define PREV_FREE_BLK_HDR_FLG 	(((UWord) 1) << 1)
+#define LAST_BLK_HDR_FLG 	(((UWord) 1) << 2)
+
+#define SBC_BLK_HDR_FLG /* Special flag combo for (allocated) SBC blocks */\
+    (THIS_FREE_BLK_HDR_FLG | PREV_FREE_BLK_HDR_FLG | LAST_BLK_HDR_FLG)
+
+/*
+ * FREE_LAST_MBC_BLK_HDR_FLGS is a special flag combo used for
+ * distinguishing empty mbc's from allocated blocks in
+ * handle_delayed_dealloc().
+ */
+#define FREE_LAST_MBC_BLK_HDR_FLGS (THIS_FREE_BLK_HDR_FLG | LAST_BLK_HDR_FLG)
+
+#define IS_FREE_LAST_MBC_BLK(B) \
+    (((B)->bhdr & FLG_MASK) == FREE_LAST_MBC_BLK_HDR_FLGS)
+
+#define IS_SBC_BLK(B) (((B)->bhdr & FLG_MASK) == SBC_BLK_HDR_FLG)
+#define IS_MBC_BLK(B) (!IS_SBC_BLK((B)))
+#define IS_FREE_BLK(B) (ASSERT(IS_MBC_BLK(B)), \
+			(B)->bhdr & THIS_FREE_BLK_HDR_FLG)
+
+#if MBC_ABLK_OFFSET_BITS
+#  define FBLK_TO_MBC(B) (ASSERT(IS_MBC_BLK(B) && IS_FREE_BLK(B)), \
+			  (B)->u.carrier)
+#  define ABLK_TO_MBC(B) \
+    (ASSERT(IS_MBC_BLK(B) && !IS_FREE_BLK(B)), \
+     (Carrier_t*)((MSEG_UNIT_FLOOR((UWord)(B)) - \
+		  (((B)->bhdr >> MBC_ABLK_OFFSET_SHIFT) << MSEG_UNIT_SHIFT))))
+#  define BLK_TO_MBC(B) (IS_FREE_BLK(B) ? FBLK_TO_MBC(B) : ABLK_TO_MBC(B))
+#else
+#  define FBLK_TO_MBC(B) ((B)->carrier)
+#  define ABLK_TO_MBC(B) ((B)->carrier)
+#  define BLK_TO_MBC(B)  ((B)->carrier)
+#endif
+#define MBC_BLK_SZ(B) (IS_FREE_BLK(B) ? MBC_FBLK_SZ(B) : MBC_ABLK_SZ(B))
+
 typedef UWord FreeBlkFtr_t; /* Footer of a free block */
 
-typedef struct {
-    UWord giga_no;
-    UWord no;
-} CallCounter_t;
+typedef Uint64 CallCounter_t;
 
 typedef struct {
     UWord		no;
@@ -298,7 +352,6 @@ typedef struct {
 	    StatValues_t	mseg;
 	    StatValues_t	sys_alloc;
 	} norm;
-	StatValues_t	small_block;
     } curr;
     StatValues_t	max;
     StatValues_t	max_ever;
@@ -358,10 +411,20 @@ typedef struct {
     size_t type_size;
     SWord list_size;
     void *list;
-    SWord max_used;
-    SWord limit;
-    SWord allocated;
-    SWord used;
+    union {
+	struct {
+	    SWord max_used;
+	    SWord limit;
+	    SWord allocated;
+	    SWord used;
+	} nocpool;
+	struct {
+	    int min_list_size;
+	    int shrink_list;
+	    UWord allocated;
+	    UWord used;
+	} cpool;
+    } u;
 } ErtsAlcFixList_t;
 
 struct Allctr_t_ {
@@ -409,37 +472,56 @@ struct Allctr_t_ {
     Uint		largest_mbc_size;
     Uint		smallest_mbc_size;
     Uint		mbc_growth_stages;
-    Uint		sbmbc_threshold;
-    Uint		sbmbc_size;
 
 #if HAVE_ERTS_MSEG
     ErtsMsegOpt_t	mseg_opt;
 #endif
 
     /* */
+    Uint		mbc_header_size;
     Uint		min_mbc_size;
     Uint		min_mbc_first_free_size;
     Uint		min_block_size;
 
     /* Carriers */
-    CarrierList_t	sbmbc_list;
     CarrierList_t	mbc_list;
     CarrierList_t	sbc_list;
+#ifdef ERTS_SMP
+    struct {
+	CarrierList_t	dc_list;
+	UWord		abandon_limit;
+	int		disable_abandon;
+	int		check_limit_count;
+	int		util_limit;
+	struct {
+	    erts_atomic_t	blocks_size;
+	    erts_atomic_t	no_blocks;
+	    erts_atomic_t	carriers_size;
+	    erts_atomic_t	no_carriers;
+	} stat;
+    } cpool;
+#endif
 
     /* Main carrier (if there is one) */
     Carrier_t *		main_carrier;
 
     /* Callback functions (first 4 are mandatory) */
     Block_t *		(*get_free_block)	(Allctr_t *, Uint,
-						 Block_t *, Uint, Uint32);
-    void		(*link_free_block)	(Allctr_t *, Block_t *, Uint32);
-    void		(*unlink_free_block)	(Allctr_t *, Block_t *, Uint32);
+						 Block_t *, Uint);
+    void		(*link_free_block)	(Allctr_t *, Block_t *);
+    void		(*unlink_free_block)	(Allctr_t *, Block_t *);
     Eterm		(*info_options)		(Allctr_t *, char *, int *,
 						 void *, Uint **, Uint *);
 
     Uint		(*get_next_mbc_size)	(Allctr_t *);
-    void		(*creating_mbc)		(Allctr_t *, Carrier_t *, Uint32);
-    void		(*destroying_mbc)	(Allctr_t *, Carrier_t *, Uint32);
+    void		(*creating_mbc)		(Allctr_t *, Carrier_t *);
+    void		(*destroying_mbc)	(Allctr_t *, Carrier_t *);
+
+    /* The three callbacks below are needed to support carrier migration */
+    void		(*add_mbc)		(Allctr_t *, Carrier_t *);
+    void		(*remove_mbc)	        (Allctr_t *, Carrier_t *);
+    UWord		(*largest_fblk_in_mbc)  (Allctr_t *, Carrier_t *);
+
     void		(*init_atoms)		(void);
 
 #ifdef ERTS_ALLOC_UTIL_HARD_DEBUG
@@ -471,8 +553,6 @@ struct Allctr_t_ {
 	CallCounter_t	this_alloc;
 	CallCounter_t	this_free;
 	CallCounter_t	this_realloc;
-	CallCounter_t	sbmbc_alloc;
-	CallCounter_t	sbmbc_free;
 	CallCounter_t	mseg_alloc;
 	CallCounter_t	mseg_dealloc;
 	CallCounter_t	mseg_realloc;
@@ -483,8 +563,7 @@ struct Allctr_t_ {
 
     CarriersStats_t	sbcs;
     CarriersStats_t	mbcs;
-    CarriersStats_t	sbmbcs;
-
+    
 #ifdef DEBUG
 #ifdef USE_THREADS
     struct {
@@ -503,6 +582,8 @@ void	erts_alcu_verify_unused_ts(Allctr_t *allctr);
 
 UWord	erts_alcu_test(UWord, UWord, UWord);
 
+void erts_alcu_assert_failed(char* expr, char* file, int line, char *func);
+
 #ifdef DEBUG
 int is_sbc_blk(Block_t*);
 #endif
diff --git a/erts/emulator/beam/erl_ao_firstfit_alloc.c b/erts/emulator/beam/erl_ao_firstfit_alloc.c
index b916cb6198..f73ac2eb6e 100644
--- a/erts/emulator/beam/erl_ao_firstfit_alloc.c
+++ b/erts/emulator/beam/erl_ao_firstfit_alloc.c
@@ -28,11 +28,16 @@
  *
  *              This module is a callback-module for erl_alloc_util.c
  *
- * Algorithm:   The tree nodes are free-blocks ordered in address order.
+ * AOFF Algorithm:
+ *              The tree nodes are ordered in address order.
  *              Every node also keeps the size of the largest block in its
- *              sub-tree ('max_size'). By that we can start from root and keep
+ *              sub-tree ('max_sz'). By that we can start from root and keep
  *              left (for low addresses) while dismissing entire sub-trees with
  *              too small blocks.
+ * AOFFCBF:
+ *              The only difference for "bestfit within carrier" is the tree
+ *              sorting order. Blocks within the same carrier are sorted
+ *              wrt size instead of address. 
  *
  * Authors: 	Rickard Green/Sverker Eriksson
  */
@@ -85,21 +90,45 @@ typedef struct AOFF_RBTree_t_ AOFF_RBTree_t;
 
 struct AOFF_RBTree_t_ {
     Block_t hdr;
-    Uint flags;
     AOFF_RBTree_t *parent;
     AOFF_RBTree_t *left;
     AOFF_RBTree_t *right;
-    Uint max_sz;  /* of all blocks in this sub-tree */
+    Uint32 flags;
+    Uint32 max_sz;  /* of all blocks in this sub-tree */
 };
 #define AOFF_BLK_SZ(B) MBC_FBLK_SZ(&(B)->hdr)
 
+typedef struct AOFF_Carrier_t_ AOFF_Carrier_t;
+
+struct AOFF_Carrier_t_ {
+    Carrier_t crr;
+    AOFF_RBTree_t rbt_node;     /* My node in the carrier tree */
+    AOFF_RBTree_t* root;        /* Root of my block tree */
+};
+#define RBT_NODE_TO_MBC(PTR) ((AOFF_Carrier_t*)((char*)(PTR) - offsetof(AOFF_Carrier_t, rbt_node)))
+
+/* 
+   To support carrier migration we keep two kinds of rb-trees:
+   1. One tree of carriers for each allocator instance.
+   2. One tree of free blocks for each carrier. 
+   Both trees use the same node structure AOFF_RBTree_t and implementation.
+   Carrier nodes thus contain a phony Block_t header 'rbt_node.hdr'.
+   The size value of such a phony block is the size of the largest free block in
+   that carrier, i.e same as 'max_sz' of the root node of its block tree.  
+*/
+
 #ifdef HARD_DEBUG
-static AOFF_RBTree_t * check_tree(AOFF_RBTree_t* root, Uint);
+#  define HARD_CHECK_IS_MEMBER(ROOT,NODE) rbt_assert_is_member(ROOT,NODE)
+#  define HARD_CHECK_TREE(CRR,BF,ROOT,SZ) check_tree(CRR, BF, ROOT, SZ)
+static AOFF_RBTree_t * check_tree(Carrier_t* within_crr, int bestfit, AOFF_RBTree_t* root, Uint);
+#else
+#  define HARD_CHECK_IS_MEMBER(ROOT,NODE)
+#  define HARD_CHECK_TREE(CRR,BF,ROOT,SZ)
 #endif
 
 
-/* Calculate 'max_size' of tree node x by only looking at the direct children
- * of x and x itself.
+/* Calculate 'max_sz' of tree node x by only looking at 'max_sz' of the
+ * direct children of x and the size x itself.
  */
 static ERTS_INLINE Uint node_max_size(AOFF_RBTree_t *x)
 {
@@ -113,7 +142,7 @@ static ERTS_INLINE Uint node_max_size(AOFF_RBTree_t *x)
     return sz;
 }
 
-/* Set new possibly lower 'max_size' of node and propagate change toward root
+/* Set new possibly lower 'max_sz' of node and propagate change toward root
 */
 static ERTS_INLINE void lower_max_size(AOFF_RBTree_t *node,
 				       AOFF_RBTree_t* stop_at)
@@ -132,32 +161,53 @@ static ERTS_INLINE void lower_max_size(AOFF_RBTree_t *node,
     else ASSERT(new_max == old_max);
 }
 
+static ERTS_INLINE SWord cmp_blocks(int bestfit,
+				    AOFF_RBTree_t* lhs, AOFF_RBTree_t* rhs)
+{
+    ASSERT(lhs != rhs);
+    ASSERT(!bestfit || FBLK_TO_MBC(&lhs->hdr) == FBLK_TO_MBC(&rhs->hdr));
+    if (bestfit) {
+	SWord diff = (SWord)AOFF_BLK_SZ(lhs) - (SWord)AOFF_BLK_SZ(rhs);
+	if (diff) return diff;
+    }
+    return (char*)lhs - (char*)rhs;
+}
+
+static ERTS_INLINE SWord cmp_cand_blk(int bestfit,
+				      Block_t* cand_blk, AOFF_RBTree_t* rhs)
+{
+    if (bestfit) {
+	if (BLK_TO_MBC(cand_blk) == FBLK_TO_MBC(&rhs->hdr)) {
+	    SWord diff = (SWord)MBC_BLK_SZ(cand_blk) - (SWord)MBC_FBLK_SZ(&rhs->hdr);
+	    if (diff) return diff;
+	}
+    }
+    return (char*)cand_blk - (char*)rhs;
+}
+
 
 /* Prototypes of callback functions */
-static Block_t*	aoff_get_free_block(Allctr_t *, Uint, Block_t *, Uint, Uint32 flags);
-static void aoff_link_free_block(Allctr_t *, Block_t*, Uint32 flags);
-static void aoff_unlink_free_block(Allctr_t *allctr, Block_t *del, Uint32 flags);
+static Block_t*	aoff_get_free_block(Allctr_t *, Uint, Block_t *, Uint);
+static void aoff_link_free_block(Allctr_t *, Block_t*);
+static void aoff_unlink_free_block(Allctr_t *allctr, Block_t *del);
+static void aoff_creating_mbc(Allctr_t*, Carrier_t*);
+static void aoff_destroying_mbc(Allctr_t*, Carrier_t*);
+static void aoff_add_mbc(Allctr_t*, Carrier_t*);
+static void aoff_remove_mbc(Allctr_t*, Carrier_t*);
+static UWord aoff_largest_fblk_in_mbc(Allctr_t*, Carrier_t*);
+
+/* Generic tree functions used by both carrier and block trees. */
+static void rbt_delete(AOFF_RBTree_t** root, AOFF_RBTree_t* del);
+static void rbt_insert(int bestfit, AOFF_RBTree_t** root, AOFF_RBTree_t* blk);
+static AOFF_RBTree_t* rbt_search(AOFF_RBTree_t* root, Uint size);
+#ifdef HARD_DEBUG
+static int rbt_assert_is_member(AOFF_RBTree_t* root, AOFF_RBTree_t* node);
+#endif
 
 static Eterm info_options(Allctr_t *, char *, int *, void *, Uint **, Uint *);
 static void init_atoms(void);
 
 
-
-#ifdef DEBUG
-
-/* Destroy all tree fields */
-#define DESTROY_TREE_NODE(N)						\
-  sys_memset((void *) (((Block_t *) (N)) + 1),				\
-	     0xff,							\
-	     (sizeof(AOFF_RBTree_t) - sizeof(Block_t)))
-
-#else
-
-#define DESTROY_TREE_NODE(N)
-
-#endif
-
-
 static int atoms_initialized = 0;
 
 void
@@ -184,11 +234,14 @@ erts_aoffalc_start(AOFFAllctr_t *alc,
 
     sys_memcpy((void *) alc, (void *) &zero.allctr, sizeof(AOFFAllctr_t));
 
+    alc->bf_within_carrier              = aoffinit->bf_within_carrier;
+    allctr->mbc_header_size		= sizeof(AOFF_Carrier_t);
     allctr->min_mbc_size		= MIN_MBC_SZ;
     allctr->min_mbc_first_free_size	= MIN_MBC_FIRST_FREE_SZ;
     allctr->min_block_size		= sizeof(AOFF_RBTree_t);
 
-    allctr->vsn_str			= ERTS_ALC_AOFF_ALLOC_VSN_STR;
+    allctr->vsn_str			= aoffinit->bf_within_carrier ?
+	ERTS_ALC_AOFF_CBF_ALLOC_VSN_STR : ERTS_ALC_AOFF_ALLOC_VSN_STR;
 
 
     /* Callback functions */
@@ -199,8 +252,11 @@ erts_aoffalc_start(AOFFAllctr_t *alc,
     allctr->info_options		= info_options;
 
     allctr->get_next_mbc_size		= NULL;
-    allctr->creating_mbc		= NULL;
-    allctr->destroying_mbc		= NULL;
+    allctr->creating_mbc		= aoff_creating_mbc;
+    allctr->destroying_mbc		= aoff_destroying_mbc;
+    allctr->add_mbc                     = aoff_add_mbc;
+    allctr->remove_mbc                  = aoff_remove_mbc;
+    allctr->largest_fblk_in_mbc         = aoff_largest_fblk_in_mbc;
     allctr->init_atoms			= init_atoms;
 
 #ifdef ERTS_ALLOC_UTIL_HARD_DEBUG
@@ -306,7 +362,6 @@ replace(AOFF_RBTree_t **root, AOFF_RBTree_t *x, AOFF_RBTree_t *y)
 
     y->max_sz = x->max_sz;
     lower_max_size(y, NULL);
-    DESTROY_TREE_NODE(x);
 }
 
 static void
@@ -403,21 +458,47 @@ tree_insert_fixup(AOFF_RBTree_t** root, AOFF_RBTree_t *blk)
 }
 
 static void
-aoff_unlink_free_block(Allctr_t *allctr, Block_t *del, Uint32 flags)
+aoff_unlink_free_block(Allctr_t *allctr, Block_t *del)
+{
+#ifdef HARD_DEBUG
+    AOFFAllctr_t* alc = (AOFFAllctr_t*)allctr;
+#endif
+    AOFF_Carrier_t *crr = (AOFF_Carrier_t*) FBLK_TO_MBC(del);
+
+    ASSERT(crr->rbt_node.hdr.bhdr == crr->root->max_sz);
+    HARD_CHECK_IS_MEMBER(alc->mbc_root, &crr->rbt_node);
+    HARD_CHECK_TREE(&crr->crr, alc->bf_within_carrier, crr->root, 0);
+
+    rbt_delete(&crr->root, (AOFF_RBTree_t*)del);
+
+    HARD_CHECK_TREE(&crr->crr, alc->bf_within_carrier, crr->root, 0);
+
+   /* Update the carrier tree with a potentially new (lower) max_sz
+    */    
+    if (crr->root) {
+	if (crr->rbt_node.hdr.bhdr == crr->root->max_sz) {
+	    return;
+	}
+	ASSERT(crr->rbt_node.hdr.bhdr > crr->root->max_sz);
+	crr->rbt_node.hdr.bhdr = crr->root->max_sz; 
+    }
+    else {
+	crr->rbt_node.hdr.bhdr = 0;
+    }
+    lower_max_size(&crr->rbt_node, NULL);
+}
+
+static void
+rbt_delete(AOFF_RBTree_t** root, AOFF_RBTree_t* del)
 {
-    AOFFAllctr_t *alc = (AOFFAllctr_t *) allctr;
-    AOFF_RBTree_t **root = ((flags & ERTS_ALCU_FLG_SBMBC)
-			    ? &alc->sbmbc_root : &alc->mbc_root);
     Uint spliced_is_black;
-    AOFF_RBTree_t *x, *y, *z = (AOFF_RBTree_t *) del;
+    AOFF_RBTree_t *x, *y, *z = del;
     AOFF_RBTree_t null_x; /* null_x is used to get the fixup started when we
 			splice out a node without children. */
 
-    null_x.parent = NULL;
+    HARD_CHECK_IS_MEMBER(*root, del);
 
-#ifdef HARD_DEBUG
-    check_tree(*root, 0);
-#endif
+    null_x.parent = NULL;
 
     /* Remove node from tree... */
 
@@ -572,26 +653,43 @@ aoff_unlink_free_block(Allctr_t *allctr, Block_t *del, Uint32 flags)
 	    RBT_ASSERT(!null_x.right);
 	}
     }
-
-    DESTROY_TREE_NODE(del);
-
-#ifdef HARD_DEBUG
-    check_tree(*root, 0);
-#endif
 }
 
 static void
-aoff_link_free_block(Allctr_t *allctr, Block_t *block, Uint32 flags)
+aoff_link_free_block(Allctr_t *allctr, Block_t *block)
 {
-    AOFFAllctr_t *alc = (AOFFAllctr_t *) allctr;
+    AOFFAllctr_t* alc = (AOFFAllctr_t*) allctr;
     AOFF_RBTree_t *blk = (AOFF_RBTree_t *) block;
-    AOFF_RBTree_t **root = ((flags & ERTS_ALCU_FLG_SBMBC)
-			    ? &alc->sbmbc_root : &alc->mbc_root);
+    AOFF_RBTree_t *crr_node;
+    AOFF_Carrier_t *blk_crr = (AOFF_Carrier_t*) FBLK_TO_MBC(block);
     Uint blk_sz = AOFF_BLK_SZ(blk);
 
-#ifdef HARD_DEBUG
-    check_tree(*root, 0);
-#endif
+    ASSERT(allctr == ERTS_ALC_CARRIER_TO_ALLCTR(&blk_crr->crr));
+    ASSERT(blk_crr->rbt_node.hdr.bhdr == (blk_crr->root ? blk_crr->root->max_sz : 0));
+    HARD_CHECK_IS_MEMBER(alc->mbc_root, &blk_crr->rbt_node);
+    HARD_CHECK_TREE(&blk_crr->crr, alc->bf_within_carrier, blk_crr->root, 0);
+
+    rbt_insert(alc->bf_within_carrier, &blk_crr->root, blk);
+
+    /* Update the carrier tree with a potential new (larger) max_sz
+    */
+    crr_node = &blk_crr->rbt_node;
+    if (blk_sz > crr_node->hdr.bhdr) {
+	ASSERT(blk_sz == blk_crr->root->max_sz);
+	crr_node->hdr.bhdr = blk_sz;
+	while (blk_sz > crr_node->max_sz) {
+	    crr_node->max_sz = blk_sz;
+	    crr_node = crr_node->parent;
+	    if (!crr_node) break;
+	}
+    }
+    HARD_CHECK_TREE(&blk_crr->crr, alc->bf_within_carrier, blk_crr->root, 0);
+}
+
+static void
+rbt_insert(int bestfit, AOFF_RBTree_t** root, AOFF_RBTree_t* blk)
+{
+    Uint blk_sz = AOFF_BLK_SZ(blk);
 
     blk->flags	= 0;
     blk->left	= NULL;
@@ -609,7 +707,7 @@ aoff_link_free_block(Allctr_t *allctr, Block_t *block, Uint32 flags)
 	    if (x->max_sz < blk_sz) {
 		x->max_sz = blk_sz;
 	    }
-	    if (blk < x) {
+	    if (cmp_blocks(bestfit, blk, x) < 0) {
 		if (!x->left) {
 		    blk->parent = x;
 		    x->left = blk;
@@ -625,7 +723,6 @@ aoff_link_free_block(Allctr_t *allctr, Block_t *block, Uint32 flags)
 		}
 		x = x->right;
 	    }
-
 	}
 
 	/* Insert block into size tree */
@@ -635,38 +732,59 @@ aoff_link_free_block(Allctr_t *allctr, Block_t *block, Uint32 flags)
 	if (IS_RED(blk->parent))
 	    tree_insert_fixup(root, blk);
     }
-
-#ifdef HARD_DEBUG
-    check_tree(*root, 0);
-#endif
 }
 
-static Block_t *
-aoff_get_free_block(Allctr_t *allctr, Uint size,
-		    Block_t *cand_blk, Uint cand_size, Uint32 flags)
+static AOFF_RBTree_t*
+rbt_search(AOFF_RBTree_t* root, Uint size)
 {
-    AOFFAllctr_t *alc = (AOFFAllctr_t *) allctr;
-    AOFF_RBTree_t *x = ((flags & ERTS_ALCU_FLG_SBMBC)
-		       ? alc->sbmbc_root : alc->mbc_root);
-    AOFF_RBTree_t *blk = NULL;
-#ifdef HARD_DEBUG
-    AOFF_RBTree_t* dbg_blk = check_tree(x, size);
-#endif
+    AOFF_RBTree_t* x = root;
 
-    ASSERT(!cand_blk || cand_size >= size);
-
-    while (x) {
+    ASSERT(x);
+    for (;;) {
 	if (x->left && x->left->max_sz >= size) {
 	    x = x->left;
 	}
 	else if (AOFF_BLK_SZ(x) >= size) {
-	    blk = x;
-	    break;
+	    return x;
 	}
 	else {
 	    x = x->right;
+	    if (!x) {
+		return NULL;
+	    }
 	}
     }
+}
+
+static Block_t *
+aoff_get_free_block(Allctr_t *allctr, Uint size,
+		    Block_t *cand_blk, Uint cand_size)
+{
+    AOFFAllctr_t *alc = (AOFFAllctr_t *) allctr;
+    AOFF_RBTree_t *crr_node = alc->mbc_root;
+    AOFF_Carrier_t* crr;
+    AOFF_RBTree_t *blk = NULL;
+#ifdef HARD_DEBUG
+    AOFF_RBTree_t* dbg_blk;
+#endif
+    
+    ASSERT(!cand_blk || cand_size >= size);
+
+    /* Get first-fit carrier
+     */
+    if (!crr_node || !(blk=rbt_search(crr_node, size))) {
+	return NULL;
+    }
+    crr = RBT_NODE_TO_MBC(blk);
+
+    /* Get block within carrier tree
+     */
+#ifdef HARD_DEBUG
+    dbg_blk = HARD_CHECK_TREE(&crr->crr, alc->bf_within_carrier, crr->root, size);
+#endif
+
+    blk = rbt_search(crr->root, size);
+    ASSERT(blk);
 
 #ifdef HARD_DEBUG
     ASSERT(blk == dbg_blk);
@@ -675,15 +793,87 @@ aoff_get_free_block(Allctr_t *allctr, Uint size,
     if (!blk)
 	return NULL;
 
-    if (cand_blk && cand_blk < &blk->hdr) {
+    if (cand_blk && cmp_cand_blk(alc->bf_within_carrier, cand_blk, blk) < 0) {
 	return NULL; /* cand_blk was better */
     }
 
-    aoff_unlink_free_block(allctr, (Block_t *) blk, flags);
+    aoff_unlink_free_block(allctr, (Block_t *) blk);
 
     return (Block_t *) blk;
 }
 
+static void aoff_creating_mbc(Allctr_t *allctr, Carrier_t *carrier)
+{
+    AOFFAllctr_t *alc = (AOFFAllctr_t *) allctr;
+    AOFF_Carrier_t *crr = (AOFF_Carrier_t*) carrier;
+    AOFF_RBTree_t **root = &alc->mbc_root;
+
+    HARD_CHECK_TREE(NULL, 0, *root, 0);
+
+    /* Link carrier in address order tree
+     */
+    crr->rbt_node.hdr.bhdr = 0;
+    rbt_insert(0, root, &crr->rbt_node);
+
+    /* aoff_link_free_block will add free block later */
+    crr->root = NULL;
+
+    HARD_CHECK_TREE(NULL, 0, *root, 0);
+}
+
+static void aoff_destroying_mbc(Allctr_t *allctr, Carrier_t *carrier)
+{
+    AOFFAllctr_t *alc = (AOFFAllctr_t *) allctr;
+    AOFF_Carrier_t *crr = (AOFF_Carrier_t*) carrier;
+    AOFF_RBTree_t *root = alc->mbc_root;
+
+    if (crr->rbt_node.parent || &crr->rbt_node == root) {
+	aoff_remove_mbc(allctr, carrier);
+    }
+    /*else already removed */
+}
+
+static void aoff_add_mbc(Allctr_t *allctr, Carrier_t *carrier)
+{
+    AOFFAllctr_t *alc = (AOFFAllctr_t *) allctr;
+    AOFF_Carrier_t *crr = (AOFF_Carrier_t*) carrier;
+    AOFF_RBTree_t **root = &alc->mbc_root;
+
+    HARD_CHECK_TREE(NULL, 0, *root, 0);   
+
+    /* Link carrier in address order tree
+     */
+    rbt_insert(0, root, &crr->rbt_node);
+
+    HARD_CHECK_TREE(NULL, 0, *root, 0);
+}
+
+static void aoff_remove_mbc(Allctr_t *allctr, Carrier_t *carrier)
+{
+    AOFFAllctr_t *alc = (AOFFAllctr_t *) allctr;
+    AOFF_Carrier_t *crr = (AOFF_Carrier_t*) carrier;
+    AOFF_RBTree_t **root = &alc->mbc_root;
+
+    ASSERT(allctr == ERTS_ALC_CARRIER_TO_ALLCTR(carrier));
+    HARD_CHECK_TREE(NULL, 0, *root, 0);
+
+    rbt_delete(root, &crr->rbt_node);
+    crr->rbt_node.parent = NULL;
+    crr->rbt_node.left = NULL;
+    crr->rbt_node.right = NULL;
+    crr->rbt_node.max_sz = crr->rbt_node.hdr.bhdr;
+
+    HARD_CHECK_TREE(NULL, 0, *root, 0);
+}
+
+static UWord aoff_largest_fblk_in_mbc(Allctr_t* allctr, Carrier_t* carrier)
+{
+    AOFF_Carrier_t *crr = (AOFF_Carrier_t*) carrier;
+
+    ASSERT(allctr == ERTS_ALC_CARRIER_TO_ALLCTR(carrier));
+    ASSERT(crr->rbt_node.hdr.bhdr == (crr->root ? crr->root->max_sz : 0));
+    return crr->rbt_node.hdr.bhdr;
+}
 
 /*
  * info_options()
@@ -692,6 +882,7 @@ aoff_get_free_block(Allctr_t *allctr, Uint size,
 static struct {
     Eterm as;
     Eterm aoff;
+    Eterm aoffcaobf;
 #ifdef DEBUG
     Eterm end_of_atoms;
 #endif
@@ -720,6 +911,7 @@ init_atoms(void)
 #endif
     AM_INIT(as);
     AM_INIT(aoff);
+    AM_INIT(aoffcaobf);
 
 #ifdef DEBUG
     for (atom = (Eterm *) &am; atom < &am.end_of_atoms; atom++) {
@@ -749,6 +941,7 @@ info_options(Allctr_t *allctr,
 	     Uint **hpp,
 	     Uint *szp)
 {
+    AOFFAllctr_t* alc = (AOFFAllctr_t*) allctr;
     Eterm res = THE_NON_VALUE;
 
     if (print_to_p) {
@@ -756,7 +949,7 @@ info_options(Allctr_t *allctr,
 		   print_to_arg,
 		   "%sas: %s\n",
 		   prefix,
-		   "aoff");
+		   alc->bf_within_carrier ? "aoffcaobf" : "aoff");
     }
 
     if (hpp || szp) {
@@ -766,7 +959,8 @@ info_options(Allctr_t *allctr,
 		     __FILE__, __LINE__);;
 
 	res = NIL;
-	add_2tup(hpp, szp, &res, am.as, am.aoff);
+	add_2tup(hpp, szp, &res, am.as,
+		 alc->bf_within_carrier ? am.aoffcaobf : am.aoff);
     }
 
     return res;
@@ -784,14 +978,19 @@ UWord
 erts_aoffalc_test(UWord op, UWord a1, UWord a2)
 {
     switch (op) {
-    case 0x500:	return (UWord) 0; /* IS_AOBF */
-    case 0x501:	return (UWord) ((AOFFAllctr_t *) a1)->mbc_root;
+    case 0x501: {
+	AOFF_RBTree_t *node = ((AOFFAllctr_t *) a1)->mbc_root; 
+	Uint size = (Uint) a2;
+	node = node ? rbt_search(node, size) : NULL;
+	return (UWord) (node ? RBT_NODE_TO_MBC(node)->root : NULL);
+    }
     case 0x502:	return (UWord) ((AOFF_RBTree_t *) a1)->parent;
     case 0x503:	return (UWord) ((AOFF_RBTree_t *) a1)->left;
     case 0x504:	return (UWord) ((AOFF_RBTree_t *) a1)->right;
     case 0x506:	return (UWord) IS_BLACK((AOFF_RBTree_t *) a1);
-    case 0x508: return (UWord) 1; /* IS_AOFF */
+    case 0x508: return (UWord) 0; /* IS_BF_ALGO */
     case 0x509: return (UWord) ((AOFF_RBTree_t *) a1)->max_sz;
+    case 0x50a: return (UWord) ((AOFFAllctr_t *) a1)->bf_within_carrier;
     default:	ASSERT(0); return ~((UWord) 0);
     }
 }
@@ -804,6 +1003,16 @@ erts_aoffalc_test(UWord op, UWord a1, UWord a2)
 
 #ifdef HARD_DEBUG
 
+static int rbt_assert_is_member(AOFF_RBTree_t* root, AOFF_RBTree_t* node)
+{
+    while (node != root) {
+	ASSERT(node->parent);
+	ASSERT(node->parent->left == node || node->parent->right == node);
+	node = node->parent;
+    }    
+    return 1;
+}
+
 #define IS_LEFT_VISITED(FB)	((FB)->flags & LEFT_VISITED_FLG)
 #define IS_RIGHT_VISITED(FB)	((FB)->flags & RIGHT_VISITED_FLG)
 
@@ -840,12 +1049,14 @@ static void print_tree(AOFF_RBTree_t*);
  */
 
 static AOFF_RBTree_t *
-check_tree(AOFF_RBTree_t* root, Uint size)
+check_tree(Carrier_t* within_crr, int bestfit, AOFF_RBTree_t* root, Uint size)
 {
     AOFF_RBTree_t *res = NULL;
     Sint blacks;
     Sint curr_blacks;
     AOFF_RBTree_t *x;
+    Carrier_t* crr;
+    Uint depth, max_depth, node_cnt;
 
 #ifdef PRINT_TREE
     print_tree(root);
@@ -859,12 +1070,16 @@ check_tree(AOFF_RBTree_t* root, Uint size)
     ASSERT(!x->parent);
     curr_blacks = 1;
     blacks = -1;
+    depth = 1;
+    max_depth = 0;
+    node_cnt = 0;
 
     while (x) {
 	if (!IS_LEFT_VISITED(x)) {
 	    SET_LEFT_VISITED(x);
 	    if (x->left) {
 		x = x->left;
+		++depth;
 		if (IS_BLACK(x))
 		    curr_blacks++;
 		continue;
@@ -880,6 +1095,7 @@ check_tree(AOFF_RBTree_t* root, Uint size)
 	    SET_RIGHT_VISITED(x);
 	    if (x->right) {
 		x = x->right;
+		++depth;
 		if (IS_BLACK(x))
 		    curr_blacks++;
 		continue;
@@ -891,6 +1107,16 @@ check_tree(AOFF_RBTree_t* root, Uint size)
 	    }
 	}
 
+	++node_cnt;
+	if (depth > max_depth)
+	    max_depth = depth;
+
+	if (within_crr) {
+	    crr = FBLK_TO_MBC(&x->hdr);
+	    ASSERT(crr == within_crr);
+	    ASSERT((char*)x > (char*)crr);
+	    ASSERT(((char*)x + AOFF_BLK_SZ(x)) <= ((char*)crr + CARRIER_SZ(crr)));
+	}
 
 	if (IS_RED(x)) {
 	    ASSERT(IS_BLACK(x->right));
@@ -901,13 +1127,13 @@ check_tree(AOFF_RBTree_t* root, Uint size)
 
 	if (x->left) {
 	    ASSERT(x->left->parent == x);
-	    ASSERT(x->left < x);
+	    ASSERT(cmp_blocks(bestfit, x->left, x) < 0);
 	    ASSERT(x->left->max_sz <= x->max_sz);	    
 	}
 
 	if (x->right) {
 	    ASSERT(x->right->parent == x);
-	    ASSERT(x->right > x);
+	    ASSERT(cmp_blocks(bestfit, x->right, x) > 0);
 	    ASSERT(x->right->max_sz <= x->max_sz);	    
 	}
 	ASSERT(x->max_sz >= AOFF_BLK_SZ(x));
@@ -916,7 +1142,7 @@ check_tree(AOFF_RBTree_t* root, Uint size)
 	       || x->max_sz == (x->right ? x->right->max_sz : 0));
 
 	if (size && AOFF_BLK_SZ(x) >= size) {
-	    if (!res || x < res) {
+	    if (!res || cmp_blocks(bestfit, x, res) < 0) {
 		res = x;
 	    }
 	}
@@ -926,10 +1152,11 @@ check_tree(AOFF_RBTree_t* root, Uint size)
 	if (IS_BLACK(x))
 	    curr_blacks--;
 	x = x->parent;
-
+	--depth;
     }
-
+    ASSERT(depth == 0 || (!root && depth==1)); 
     ASSERT(curr_blacks == 0);
+    ASSERT((1 << (max_depth/2)) <= node_cnt);
 
     UNSET_LEFT_VISITED(root);
     UNSET_RIGHT_VISITED(root);
@@ -954,9 +1181,9 @@ print_tree_aux(AOFF_RBTree_t *x, int indent)
 	for (i = 0; i < indent; i++) {
 	    putc(' ', stderr);
 	}
-	fprintf(stderr, "%s: sz=%lu addr=0x%lx max_size=%lu\r\n",
+	fprintf(stderr, "%s: sz=%lu addr=0x%lx max_size=%u\r\n",
 		IS_BLACK(x) ? "BLACK" : "RED",
-		AOFF_BLK_SZ(x), (Uint)x, x->max_sz);
+		AOFF_BLK_SZ(x), (Uint)x, (unsigned)x->max_sz);
 	print_tree_aux(x->left,  indent + INDENT_STEP);
     }
 }
diff --git a/erts/emulator/beam/erl_ao_firstfit_alloc.h b/erts/emulator/beam/erl_ao_firstfit_alloc.h
index 21c36c6654..87427e8e62 100644
--- a/erts/emulator/beam/erl_ao_firstfit_alloc.h
+++ b/erts/emulator/beam/erl_ao_firstfit_alloc.h
@@ -24,11 +24,12 @@
 #include "erl_alloc_util.h"
 
 #define ERTS_ALC_AOFF_ALLOC_VSN_STR "0.9"
+#define ERTS_ALC_AOFF_CBF_ALLOC_VSN_STR "0.9"
 
 typedef struct AOFFAllctr_t_ AOFFAllctr_t;
 
 typedef struct {
-    int dummy;
+    int bf_within_carrier;
 } AOFFAllctrInit_t;
 
 #define ERTS_DEFAULT_AOFF_ALLCTR_INIT {0/*dummy*/}
@@ -51,7 +52,7 @@ struct AOFFAllctr_t_ {
     Allctr_t		allctr; /* Has to be first! */
 
     struct AOFF_RBTree_t_* mbc_root;
-    struct AOFF_RBTree_t_* sbmbc_root;
+    int bf_within_carrier;
 };
 
 UWord erts_aoffalc_test(UWord, UWord, UWord);
diff --git a/erts/emulator/beam/erl_bestfit_alloc.c b/erts/emulator/beam/erl_bestfit_alloc.c
index ed843a51fb..58e53c3d00 100644
--- a/erts/emulator/beam/erl_bestfit_alloc.c
+++ b/erts/emulator/beam/erl_bestfit_alloc.c
@@ -89,21 +89,21 @@
 static RBTree_t * check_tree(RBTree_t, int, Uint);
 #endif
 
-static void tree_delete(Allctr_t *allctr, Block_t *del, Uint32 flags);
+static void tree_delete(Allctr_t *allctr, Block_t *del);
 
 /* Prototypes of callback functions */
 
 /* "address order best fit" specific callback functions */
 static Block_t *	aobf_get_free_block	(Allctr_t *, Uint,
-						 Block_t *, Uint, Uint32);
-static void		aobf_link_free_block	(Allctr_t *, Block_t *, Uint32);
+						 Block_t *, Uint);
+static void		aobf_link_free_block	(Allctr_t *, Block_t *);
 #define			aobf_unlink_free_block	tree_delete
 
 /* "best fit" specific callback functions */
 static Block_t *	bf_get_free_block	(Allctr_t *, Uint,
-						 Block_t *, Uint, Uint32);
-static void		bf_link_free_block	(Allctr_t *, Block_t *, Uint32);
-static ERTS_INLINE void	bf_unlink_free_block	(Allctr_t *, Block_t *, Uint32);
+						 Block_t *, Uint);
+static void		bf_link_free_block	(Allctr_t *, Block_t *);
+static ERTS_INLINE void	bf_unlink_free_block	(Allctr_t *, Block_t *);
 
 
 static Eterm		info_options		(Allctr_t *, char *, int *,
@@ -179,6 +179,7 @@ erts_bfalc_start(BFAllctr_t *bfallctr,
     bfallctr->address_order		= bfinit->ao;
 
 
+    allctr->mbc_header_size		= sizeof(Carrier_t);
     allctr->min_mbc_size		= MIN_MBC_SZ;
     allctr->min_mbc_first_free_size	= MIN_MBC_FIRST_FREE_SZ;
     allctr->min_block_size		= (bfinit->ao
@@ -207,6 +208,9 @@ erts_bfalc_start(BFAllctr_t *bfallctr,
     allctr->get_next_mbc_size		= NULL;
     allctr->creating_mbc		= NULL;
     allctr->destroying_mbc		= NULL;
+    allctr->add_mbc                     = NULL;
+    allctr->remove_mbc		        = NULL;
+    allctr->largest_fblk_in_mbc         = NULL;
     allctr->init_atoms			= init_atoms;
 
 #ifdef ERTS_ALLOC_UTIL_HARD_DEBUG
@@ -407,13 +411,11 @@ tree_insert_fixup(RBTree_t **root, RBTree_t *blk)
  * callback function in the address order case.
  */
 static void
-tree_delete(Allctr_t *allctr, Block_t *del, Uint32 flags)
+tree_delete(Allctr_t *allctr, Block_t *del)
 {
     BFAllctr_t *bfallctr = (BFAllctr_t *) allctr;
     Uint spliced_is_black;
-    RBTree_t **root = ((flags & ERTS_ALCU_FLG_SBMBC)
-		       ? &bfallctr->sbmbc_root
-		       : &bfallctr->mbc_root);
+    RBTree_t **root = &bfallctr->mbc_root;
     RBTree_t *x, *y, *z = (RBTree_t *) del;
     RBTree_t null_x; /* null_x is used to get the fixup started when we
 			splice out a node without children. */
@@ -586,12 +588,10 @@ tree_delete(Allctr_t *allctr, Block_t *del, Uint32 flags)
 \*                                                                           */
 
 static void
-aobf_link_free_block(Allctr_t *allctr, Block_t *block, Uint32 flags)
+aobf_link_free_block(Allctr_t *allctr, Block_t *block)
 {
     BFAllctr_t *bfallctr = (BFAllctr_t *) allctr;
-    RBTree_t **root = ((flags & ERTS_ALCU_FLG_SBMBC)
-		       ? &bfallctr->sbmbc_root
-		       : &bfallctr->mbc_root);
+    RBTree_t **root = &bfallctr->mbc_root;
     RBTree_t *blk = (RBTree_t *) block;
     Uint blk_sz = BF_BLK_SZ(blk);
 
@@ -647,21 +647,18 @@ aobf_link_free_block(Allctr_t *allctr, Block_t *block, Uint32 flags)
 
 #if 0 /* tree_delete() is directly used instead */
 static void
-aobf_unlink_free_block(Allctr_t *allctr, Block_t *block, Uint32 flags)
+aobf_unlink_free_block(Allctr_t *allctr, Block_t *block)
 {
-    tree_delete(allctr, block, flags);
+    tree_delete(allctr, block);
 }
 #endif
 
 static Block_t *
 aobf_get_free_block(Allctr_t *allctr, Uint size,
-		    Block_t *cand_blk, Uint cand_size,
-		    Uint32 flags)
+		    Block_t *cand_blk, Uint cand_size)
 {
     BFAllctr_t *bfallctr = (BFAllctr_t *) allctr;
-    RBTree_t **root = ((flags & ERTS_ALCU_FLG_SBMBC)
-		       ? &bfallctr->sbmbc_root
-		       : &bfallctr->mbc_root);
+    RBTree_t **root = &bfallctr->mbc_root;
     RBTree_t *x = *root;
     RBTree_t *blk = NULL;
     Uint blk_sz;
@@ -694,7 +691,7 @@ aobf_get_free_block(Allctr_t *allctr, Uint size,
 	    return NULL; /* cand_blk was better */
     }
 
-    aobf_unlink_free_block(allctr, (Block_t *) blk, flags);
+    aobf_unlink_free_block(allctr, (Block_t *) blk);
 
     return (Block_t *) blk;
 }
@@ -705,12 +702,10 @@ aobf_get_free_block(Allctr_t *allctr, Uint size,
 \*                                                                           */
 
 static void
-bf_link_free_block(Allctr_t *allctr, Block_t *block, Uint32 flags)
+bf_link_free_block(Allctr_t *allctr, Block_t *block)
 {
     BFAllctr_t *bfallctr = (BFAllctr_t *) allctr;
-    RBTree_t **root = ((flags & ERTS_ALCU_FLG_SBMBC)
-		       ? &bfallctr->sbmbc_root
-		       : &bfallctr->mbc_root);
+    RBTree_t **root = &bfallctr->mbc_root;
     RBTree_t *blk = (RBTree_t *) block;
     Uint blk_sz = BF_BLK_SZ(blk);
 
@@ -779,12 +774,10 @@ bf_link_free_block(Allctr_t *allctr, Block_t *block, Uint32 flags)
 }
 
 static ERTS_INLINE void
-bf_unlink_free_block(Allctr_t *allctr, Block_t *block, Uint32 flags)
+bf_unlink_free_block(Allctr_t *allctr, Block_t *block)
 {
     BFAllctr_t *bfallctr = (BFAllctr_t *) allctr;
-    RBTree_t **root = ((flags & ERTS_ALCU_FLG_SBMBC)
-		       ? &bfallctr->sbmbc_root
-		       : &bfallctr->mbc_root);
+    RBTree_t **root = &bfallctr->mbc_root;
     RBTree_t *x = (RBTree_t *) block;
 
     if (IS_LIST_ELEM(x)) {
@@ -812,7 +805,7 @@ bf_unlink_free_block(Allctr_t *allctr, Block_t *block, Uint32 flags)
     }
     else {
 	/* Remove from tree */
-	tree_delete(allctr, block, flags);
+	tree_delete(allctr, block);
     }
 
     DESTROY_LIST_ELEM(x);
@@ -821,13 +814,10 @@ bf_unlink_free_block(Allctr_t *allctr, Block_t *block, Uint32 flags)
 
 static Block_t *
 bf_get_free_block(Allctr_t *allctr, Uint size,
-		  Block_t *cand_blk, Uint cand_size,
-		  Uint32 flags)
+		  Block_t *cand_blk, Uint cand_size)
 {
     BFAllctr_t *bfallctr = (BFAllctr_t *) allctr;
-    RBTree_t **root = ((flags & ERTS_ALCU_FLG_SBMBC)
-		       ? &bfallctr->sbmbc_root
-		       : &bfallctr->mbc_root);
+    RBTree_t **root = &bfallctr->mbc_root;
     RBTree_t *x = *root;
     RBTree_t *blk = NULL;
     Uint blk_sz;
@@ -867,7 +857,7 @@ bf_get_free_block(Allctr_t *allctr, Uint size,
        the tree node */
     blk = LIST_NEXT(blk) ? LIST_NEXT(blk) : blk;
 
-    bf_unlink_free_block(allctr, (Block_t *) blk, flags);
+    bf_unlink_free_block(allctr, (Block_t *) blk);
     return (Block_t *) blk;
 }
 
@@ -984,7 +974,7 @@ erts_bfalc_test(UWord op, UWord a1, UWord a2)
     case 0x205:	return (UWord) ((RBTreeList_t *) a1)->next;
     case 0x206:	return (UWord) IS_BLACK((RBTree_t *) a1);
     case 0x207:	return (UWord) IS_TREE_NODE((RBTree_t *) a1);
-    case 0x208:	return (UWord) 0; /* IS_AOFF */
+    case 0x208:	return (UWord) 1; /* IS_BF_ALGO */
     default:	ASSERT(0); return ~((UWord) 0);
     }
 }
diff --git a/erts/emulator/beam/erl_bestfit_alloc.h b/erts/emulator/beam/erl_bestfit_alloc.h
index f2d2f07d7a..be8b2b871d 100644
--- a/erts/emulator/beam/erl_bestfit_alloc.h
+++ b/erts/emulator/beam/erl_bestfit_alloc.h
@@ -55,7 +55,6 @@ struct BFAllctr_t_ {
     Allctr_t		allctr; /* Has to be first! */
 
     RBTree_t *		mbc_root;
-    RBTree_t *		sbmbc_root;
     int 		address_order;
 };
 
diff --git a/erts/emulator/beam/erl_bif_info.c b/erts/emulator/beam/erl_bif_info.c
index 1744afbae1..74a37f374d 100755
--- a/erts/emulator/beam/erl_bif_info.c
+++ b/erts/emulator/beam/erl_bif_info.c
@@ -1671,13 +1671,22 @@ info_1_tuple(Process* BIF_P,	/* Pointer to current process. */
 
     sel = *tp++;
 
-    if (sel == am_allocator_sizes) {
+    if (sel == am_memory_internal) {
+	switch (arity) {
+	case 3:
+	    if (erts_request_alloc_info(BIF_P, tp[0], tp[1], 1, 1))
+		return am_true;
+	default:
+	    goto badarg;
+	}
+    }
+    else if (sel == am_allocator_sizes) {
 	switch (arity) {
 	case 2:
 	    ERTS_BIF_PREP_TRAP1(ret, alloc_sizes_trap, BIF_P, *tp);
 	    return ret;
 	case 3:
-	    if (erts_request_alloc_info(BIF_P, tp[0], tp[1], 1))
+	    if (erts_request_alloc_info(BIF_P, tp[0], tp[1], 1, 0))
 		return am_true;
 	default:
 	    goto badarg;
@@ -1736,7 +1745,7 @@ info_1_tuple(Process* BIF_P,	/* Pointer to current process. */
 	    ERTS_BIF_PREP_TRAP1(ret, alloc_info_trap, BIF_P, *tp);
 	    return ret;
 	case 3:
-	    if (erts_request_alloc_info(BIF_P, tp[0], tp[1], 0))
+	    if (erts_request_alloc_info(BIF_P, tp[0], tp[1], 0, 0))
 		return am_true;
 	default:
 	    goto badarg;
diff --git a/erts/emulator/beam/erl_goodfit_alloc.c b/erts/emulator/beam/erl_goodfit_alloc.c
index 79d8b40f8c..e9d8249ee1 100644
--- a/erts/emulator/beam/erl_goodfit_alloc.c
+++ b/erts/emulator/beam/erl_goodfit_alloc.c
@@ -163,10 +163,10 @@ BKT_MIN_SZ(GFAllctr_t *gfallctr, int ix)
 
 /* Prototypes of callback functions */
 static Block_t *	get_free_block		(Allctr_t *, Uint,
-						 Block_t *, Uint, Uint32);
-static void		link_free_block		(Allctr_t *, Block_t *, Uint32);
-static void		unlink_free_block	(Allctr_t *, Block_t *, Uint32);
-static void		update_last_aux_mbc	(Allctr_t *, Carrier_t *, Uint32);
+						 Block_t *, Uint);
+static void		link_free_block		(Allctr_t *, Block_t *);
+static void		unlink_free_block	(Allctr_t *, Block_t *);
+static void		update_last_aux_mbc	(Allctr_t *, Carrier_t *);
 static Eterm		info_options		(Allctr_t *, char *, int *,
 						 void *, Uint **, Uint *);
 static void		init_atoms		(void);
@@ -203,8 +203,7 @@ erts_gfalc_start(GFAllctr_t *gfallctr,
 
     sys_memcpy((void *) gfallctr, (void *) &zero.allctr, sizeof(GFAllctr_t));
 
-    init->sbmbct = 0; /* Small mbc not yet supported by goodfit */
-
+    allctr->mbc_header_size		= sizeof(Carrier_t);
     allctr->min_mbc_size		= MIN_MBC_SZ;
     allctr->min_mbc_first_free_size	= MIN_MBC_FIRST_FREE_SZ;
     allctr->min_block_size		= sizeof(GFFreeBlock_t);
@@ -222,7 +221,9 @@ erts_gfalc_start(GFAllctr_t *gfallctr,
     allctr->get_next_mbc_size		= NULL;
     allctr->creating_mbc		= update_last_aux_mbc;
     allctr->destroying_mbc		= update_last_aux_mbc;
-
+    allctr->add_mbc		        = NULL;
+    allctr->remove_mbc		        = NULL;
+    allctr->largest_fblk_in_mbc         = NULL;
     allctr->init_atoms			= init_atoms;
 
 #ifdef ERTS_ALLOC_UTIL_HARD_DEBUG
@@ -384,7 +385,7 @@ search_bucket(Allctr_t *allctr, int ix, Uint size)
 
 static Block_t *
 get_free_block(Allctr_t *allctr, Uint size,
-	       Block_t *cand_blk, Uint cand_size, Uint32 flags)
+	       Block_t *cand_blk, Uint cand_size)
 {
     GFAllctr_t *gfallctr = (GFAllctr_t *) allctr;
     int unsafe_bi, min_bi;
@@ -403,7 +404,7 @@ get_free_block(Allctr_t *allctr, Uint size,
 	if (blk) {
 	    if (cand_blk && cand_size <= MBC_FBLK_SZ(blk))
 		return NULL; /* cand_blk was better */
-	    unlink_free_block(allctr, blk, flags);
+	    unlink_free_block(allctr, blk);
 	    return blk;
 	}
 	if (min_bi < NO_OF_BKTS - 1) {
@@ -423,14 +424,14 @@ get_free_block(Allctr_t *allctr, Uint size,
     ASSERT(blk);
     if (cand_blk && cand_size <= MBC_FBLK_SZ(blk))
 	return NULL; /* cand_blk was better */
-    unlink_free_block(allctr, blk, flags);
+    unlink_free_block(allctr, blk);
     return blk;
 }
 
 
 
 static void
-link_free_block(Allctr_t *allctr, Block_t *block, Uint32 flags)
+link_free_block(Allctr_t *allctr, Block_t *block)
 {
     GFAllctr_t *gfallctr = (GFAllctr_t *) allctr;
     GFFreeBlock_t *blk = (GFFreeBlock_t *) block;
@@ -451,7 +452,7 @@ link_free_block(Allctr_t *allctr, Block_t *block, Uint32 flags)
 }
 
 static void
-unlink_free_block(Allctr_t *allctr, Block_t *block, Uint32 flags)
+unlink_free_block(Allctr_t *allctr, Block_t *block)
 {
     GFAllctr_t *gfallctr = (GFAllctr_t *) allctr;
     GFFreeBlock_t *blk = (GFFreeBlock_t *) block;
@@ -472,7 +473,7 @@ unlink_free_block(Allctr_t *allctr, Block_t *block, Uint32 flags)
 }
 
 static void
-update_last_aux_mbc(Allctr_t *allctr, Carrier_t *mbc, Uint32 flags)
+update_last_aux_mbc(Allctr_t *allctr, Carrier_t *mbc)
 {
     GFAllctr_t *gfallctr = (GFAllctr_t *) allctr;
 
diff --git a/erts/emulator/beam/erl_instrument.c b/erts/emulator/beam/erl_instrument.c
index 1aea3f65bc..df7c443387 100644
--- a/erts/emulator/beam/erl_instrument.c
+++ b/erts/emulator/beam/erl_instrument.c
@@ -1236,8 +1236,6 @@ erts_instr_init(int stat, int map_stat)
     sys_memzero((void *) stats->n, sizeof(Stat_t)*(ERTS_ALC_N_MAX+1));
 
     for (i = ERTS_ALC_A_MIN; i <= ERTS_ALC_A_MAX; i++) {
-	if (ERTS_IS_SBMBC_ALLOCATOR_NO__(i))
-	    continue;
 	if (erts_allctrs_info[i].enabled)
 	    stats->ap[i] = &stats->a[i];
 	else
@@ -1251,8 +1249,6 @@ erts_instr_init(int stat, int map_stat)
 	erts_instr_memory_map = 1;
 	erts_instr_stat = 1;
 	for (i = ERTS_ALC_A_MIN; i <= ERTS_ALC_A_MAX; i++) {
-	    if (ERTS_IS_SBMBC_ALLOCATOR_NO__(i))
-		continue;
 	    erts_allctrs[i].alloc	= map_stat_alloc;
 	    erts_allctrs[i].realloc	= map_stat_realloc;
 	    erts_allctrs[i].free	= map_stat_free;
@@ -1265,8 +1261,6 @@ erts_instr_init(int stat, int map_stat)
     else {
 	erts_instr_stat = 1;
 	for (i = ERTS_ALC_A_MIN; i <= ERTS_ALC_A_MAX; i++) {
-	    if (ERTS_IS_SBMBC_ALLOCATOR_NO__(i))
-		continue;
 	    erts_allctrs[i].alloc	= stat_alloc;
 	    erts_allctrs[i].realloc	= stat_realloc;
 	    erts_allctrs[i].free	= stat_free;
diff --git a/erts/emulator/beam/erl_lock_check.c b/erts/emulator/beam/erl_lock_check.c
index a1d270adba..bc59fe55d4 100644
--- a/erts/emulator/beam/erl_lock_check.c
+++ b/erts/emulator/beam/erl_lock_check.c
@@ -150,7 +150,6 @@ static erts_lc_lock_order_t erts_lock_order[] = {
     {	"instr_x",				NULL			},
     {	"instr",				NULL			},
     {	"alcu_allocator",			"index"			},
-    {	"sbmbc_alloc",				"index"			},
     {	"mseg",					NULL			},
 #if HALFWORD_HEAP
     {	"pmmap",				NULL			},
diff --git a/erts/emulator/beam/erl_process.c b/erts/emulator/beam/erl_process.c
index 81799ddbb1..88eb224f84 100644
--- a/erts/emulator/beam/erl_process.c
+++ b/erts/emulator/beam/erl_process.c
@@ -1327,6 +1327,17 @@ erts_alloc_notify_delayed_dealloc(int ix)
 				       ERTS_SSI_AUX_WORK_DD);
 }
 
+void
+erts_alloc_ensure_handle_delayed_dealloc_call(int ix)
+{
+#ifdef DEBUG
+    ErtsSchedulerData *esdp = erts_get_scheduler_data();
+    ASSERT(!esdp || ix == (int) esdp->no);
+#endif
+    set_aux_work_flags_wakeup_nob(ERTS_SCHED_SLEEP_INFO_IX(ix-1),
+				  ERTS_SSI_AUX_WORK_DD);
+}
+
 static ERTS_INLINE erts_aint32_t
 handle_delayed_dealloc(ErtsAuxWorkData *awdp, erts_aint32_t aux_work, int waiting)
 {
diff --git a/erts/emulator/beam/erl_process.h b/erts/emulator/beam/erl_process.h
index 7dd8116857..865ac6c43f 100644
--- a/erts/emulator/beam/erl_process.h
+++ b/erts/emulator/beam/erl_process.h
@@ -1340,6 +1340,7 @@ int erts_is_multi_scheduling_blocked(void);
 Eterm erts_multi_scheduling_blockers(Process *);
 void erts_start_schedulers(void);
 void erts_alloc_notify_delayed_dealloc(int);
+void erts_alloc_ensure_handle_delayed_dealloc_call(int);
 void erts_smp_notify_check_children_needed(void);
 #endif
 #if ERTS_USE_ASYNC_READY_Q
diff --git a/erts/emulator/test/alloc_SUITE.erl b/erts/emulator/test/alloc_SUITE.erl
index 22b5d93983..33abd45982 100644
--- a/erts/emulator/test/alloc_SUITE.erl
+++ b/erts/emulator/test/alloc_SUITE.erl
@@ -28,7 +28,8 @@
 	 bucket_index/1,
 	 bucket_mask/1,
 	 rbtree/1,
-	 mseg_clear_cache/1]).
+	 mseg_clear_cache/1,
+	 cpool/1]).
 
 -export([init_per_testcase/2, end_per_testcase/2]).
 
@@ -40,7 +41,7 @@ suite() -> [{ct_hooks,[ts_install_cth]}].
 
 all() -> 
     [basic, coalesce, threads, realloc_copy, bucket_index,
-     bucket_mask, rbtree, mseg_clear_cache].
+     bucket_mask, rbtree, mseg_clear_cache, cpool].
 
 groups() -> 
     [].
@@ -105,6 +106,10 @@ mseg_clear_cache(suite) -> [];
 mseg_clear_cache(doc) ->   [];
 mseg_clear_cache(Cfg) -> ?line drv_case(Cfg).
 
+cpool(suite) -> [];
+cpool(doc) ->   [];
+cpool(Cfg) -> ?line drv_case(Cfg).
+
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %%                                                                        %%
 %% Internal functions                                                     %%
diff --git a/erts/emulator/test/alloc_SUITE_data/Makefile.src b/erts/emulator/test/alloc_SUITE_data/Makefile.src
index 035415d73e..1d4286e671 100644
--- a/erts/emulator/test/alloc_SUITE_data/Makefile.src
+++ b/erts/emulator/test/alloc_SUITE_data/Makefile.src
@@ -23,7 +23,8 @@ TEST_DRVS =	basic@dll@		\
 		bucket_index@dll@	\
 		bucket_mask@dll@	\
 		rbtree@dll@		\
-		mseg_clear_cache@dll@
+		mseg_clear_cache@dll@	\
+		cpool@dll@
 
 CC = @CC@
 LD = @LD@
diff --git a/erts/emulator/test/alloc_SUITE_data/allocator_test.h b/erts/emulator/test/alloc_SUITE_data/allocator_test.h
index c0396ddb61..c37b074f93 100644
--- a/erts/emulator/test/alloc_SUITE_data/allocator_test.h
+++ b/erts/emulator/test/alloc_SUITE_data/allocator_test.h
@@ -75,6 +75,15 @@ typedef void* erts_cond;
 #define PREV_BLK(B)		((Block_t *)	ALC_TEST1(0x019, (B)))
 #define IS_MBC_FIRST_BLK(A,B)	((Ulong)	ALC_TEST2(0x01a, (A), (B)))
 #define UNIT_SZ			((Ulong)	ALC_TEST0(0x01b))
+#define BLK_TO_MBC(B)		((Carrier_t *)	ALC_TEST1(0x01c, (B)))
+#define ADD_MBC(A, C)        	((void)	ALC_TEST2(0x01d, (A), (C)))
+#define REMOVE_MBC(A, C)       	((void)	ALC_TEST2(0x01e, (A), (C)))
+#define ZERO_CRR_SIZE		((Ulong)	ALC_TEST0(0x01f))
+#define ZERO_CRR_INIT(A,B)	((Carrier_t *)	ALC_TEST2(0x020, (A), (B)))
+#define CPOOL_INSERT(A,B)	((Carrier_t *)	ALC_TEST2(0x021, (A), (B)))
+#define CPOOL_DELETE(A,B)	((Carrier_t *)	ALC_TEST2(0x022, (A), (B)))
+#define CPOOL_IS_EMPTY(A)	((int)		ALC_TEST1(0x023, (A)))
+#define CPOOL_IS_IN_POOL(A,B)	((int)		ALC_TEST2(0x024, (A), (B)))
 
 /* From erl_goodfit_alloc.c */
 #define BKT_IX(A, S)		((Ulong)	ALC_TEST2(0x100, (A), (S)))
@@ -84,15 +93,16 @@ typedef void* erts_cond;
 
 /* From erl_bestfit_alloc.c and erl_ao_firstfit_alloc.c */
 #define IS_AOBF(A)		((Ulong)	ALC_TEST1(RBT_OP(0), (A)))
-#define RBT_ROOT(A)		((RBT_t *)	ALC_TEST1(RBT_OP(1), (A)))
+#define RBT_ROOT(A,SZ)		((RBT_t *)	ALC_TEST2(RBT_OP(1), (A), (SZ)))
 #define RBT_PARENT(T)		((RBT_t *)	ALC_TEST1(RBT_OP(2), (T)))
 #define RBT_LEFT(T)		((RBT_t *)	ALC_TEST1(RBT_OP(3), (T)))
 #define RBT_RIGHT(T)		((RBT_t *)	ALC_TEST1(RBT_OP(4), (T)))
 #define RBT_NEXT(T)		((RBTL_t *)	ALC_TEST1(RBT_OP(5), (T)))
 #define RBT_IS_BLACK(T)		((Ulong)	ALC_TEST1(RBT_OP(6), (T)))
 #define RBT_IS_TREE(T)		((Ulong)	ALC_TEST1(RBT_OP(7), (T)))
-#define IS_AOFF(A)		((Ulong)	ALC_TEST1(RBT_OP(8), (A)))
+#define IS_BF_ALGO(A)		((Ulong)	ALC_TEST1(RBT_OP(8), (A)))
 #define RBT_MAX_SZ(T)		((Ulong)	ALC_TEST1(RBT_OP(9), (T)))
+#define IS_CBF(A)		((Ulong)	ALC_TEST1(RBT_OP(0xa), (A)))
 
 /* From erl_mseg.c */
 #define HAVE_MSEG()		((int)		ALC_TEST0(0x400))
@@ -129,5 +139,6 @@ typedef void* erts_cond;
 #define THR_CREATE(F, A)	((erts_thread)	ALC_TEST2(0xf10, (F), (A)))
 #define THR_JOIN(T)		((void)		ALC_TEST1(0xf11, (T)))
 #define THR_EXIT(R)		((void)		ALC_TEST1(0xf12, (R)))
+#define IS_SMP_ENABLED		((int)		ALC_TEST0(0xf13))
 
 #endif
diff --git a/erts/emulator/test/alloc_SUITE_data/coalesce.c b/erts/emulator/test/alloc_SUITE_data/coalesce.c
index 981fa6d43e..36710bf7b5 100644
--- a/erts/emulator/test/alloc_SUITE_data/coalesce.c
+++ b/erts/emulator/test/alloc_SUITE_data/coalesce.c
@@ -267,7 +267,7 @@ void
 testcase_run(TestCaseState_t *tcs)
 {
     char *argv_org[] = {"-tsmbcs511","-tmmbcs511", "-tsbct512", "-trmbcmt100", "-tas", NULL, NULL};
-    char *alg[] = {"af", "gf", "bf", "aobf", "aoff", NULL};
+    char *alg[] = {"af", "gf", "bf", "aobf", "aoff", "aoffcaobf", NULL};
     int i;
 
     for (i = 0; alg[i]; i++) {
diff --git a/erts/emulator/test/alloc_SUITE_data/cpool.c b/erts/emulator/test/alloc_SUITE_data/cpool.c
new file mode 100644
index 0000000000..276ed7be04
--- /dev/null
+++ b/erts/emulator/test/alloc_SUITE_data/cpool.c
@@ -0,0 +1,157 @@
+/*
+ * %CopyrightBegin%
+ *
+ * Copyright Ericsson AB 2013. All Rights Reserved.
+ *
+ * The contents of this file are subject to the Erlang Public License,
+ * Version 1.1, (the "License"); you may not use this file except in
+ * compliance with the License. You should have received a copy of the
+ * Erlang Public License along with this software. If not, it can be
+ * retrieved online at http://www.erlang.org/.
+ *
+ * Software distributed under the License is distributed on an "AS IS"
+ * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+ * the License for the specific language governing rights and limitations
+ * under the License.
+ *
+ * %CopyrightEnd%
+ */
+
+
+#ifndef __WIN32__
+#include <sys/types.h>
+#include <unistd.h>
+#include <errno.h>
+#endif
+#include <stdio.h>
+#include <stdarg.h>
+#include <string.h>
+#include "testcase_driver.h"
+#include "allocator_test.h"
+
+#define FATAL_ASSERT(A)						\
+    ((void) ((A)						\
+	     ? 1						\
+	     : (fatal_assert_failed(#A,				\
+				    (char *) __FILE__,		\
+				    __LINE__),			\
+		0)))
+
+static void
+fatal_assert_failed(char* expr, char* file, int line)
+{
+    fflush(stdout);
+    fprintf(stderr, "%s:%d: Assertion failed: %s\n",
+	    file, line, expr);
+    fflush(stderr);
+    abort();
+}
+
+#define TEST_NO_THREADS 10
+#define TEST_NO_CARRIERS_PER_THREAD 100000
+#define TEST_CARRIERS_OFFSET 5
+
+static Allctr_t *alloc = NULL;
+
+static void stop_allocator(void)
+{
+    if (alloc) {
+	STOP_ALC(alloc);
+	alloc = NULL;
+    }
+}
+
+
+void *thread_func(void *arg);
+
+char *
+testcase_name(void)
+{
+    return "cpool";
+}
+
+void
+testcase_cleanup(TestCaseState_t *tcs)
+{
+    stop_allocator();
+}
+
+void *
+thread_func(void *arg)
+{
+    Carrier_t *crr = (Carrier_t *) arg;
+    int i;
+
+    for (i = 0; i < (TEST_NO_CARRIERS_PER_THREAD+TEST_CARRIERS_OFFSET); i++) {
+	int d;
+	if (i < TEST_NO_CARRIERS_PER_THREAD) {
+	    CPOOL_INSERT(alloc, crr[i]);
+	    if ((i & 0x7) == 0)
+		FATAL_ASSERT(CPOOL_IS_IN_POOL(alloc, crr[i]));
+	}
+	d = i-TEST_CARRIERS_OFFSET;
+	if (d >= 0) {
+	    CPOOL_DELETE(alloc, crr[d]);
+	    if ((d & 0x7) == 0)
+		FATAL_ASSERT(!CPOOL_IS_IN_POOL(alloc, crr[d]));
+	}
+    }
+    for (i = 0; i < TEST_NO_CARRIERS_PER_THREAD; i++)
+	FATAL_ASSERT(!CPOOL_IS_IN_POOL(alloc, crr[i]));
+    return NULL;
+}
+
+static struct {
+    erts_thread tid;
+    Carrier_t *crr[TEST_NO_CARRIERS_PER_THREAD];
+} threads[TEST_NO_THREADS] = {{0}};
+
+void
+testcase_run(TestCaseState_t *tcs)
+{
+    int no_threads, t, c;
+    char *block, *p;
+    Ulong zcrr_sz;
+
+    if (!IS_SMP_ENABLED)
+	testcase_skipped(tcs, "No SMP support");
+
+    alloc = START_ALC("Zero carrier allocator", 1, NULL);
+
+    zcrr_sz = ZERO_CRR_SIZE;
+
+    block = p = ALLOC(alloc, zcrr_sz*TEST_NO_THREADS*TEST_NO_CARRIERS_PER_THREAD);
+
+    ASSERT(tcs, block != NULL);    
+
+    for (t = 0; t < TEST_NO_THREADS; t++) {
+	for (c = 0; c < TEST_NO_CARRIERS_PER_THREAD; c++) {
+	    Carrier_t *crr = (Carrier_t *) p;
+	    p += zcrr_sz;
+	    ZERO_CRR_INIT(alloc, crr);
+	    threads[t].crr[c] = crr;
+	}
+    }
+
+    no_threads = 0;
+    for (t = 0; t < TEST_NO_THREADS; t++) {
+    	threads[t].tid = THR_CREATE(thread_func, (void *) threads[t].crr);
+	if (threads[t].tid) {
+	    testcase_printf(tcs, "Successfully created thread %d\n", t);
+	    no_threads++;
+	}
+	else {
+	    testcase_printf(tcs, "Failed to create thread %d\n", t);
+	    break;
+	}
+    }
+
+    for (t = 0; t < no_threads; t++)
+	THR_JOIN(threads[t].tid);
+
+    FATAL_ASSERT(CPOOL_IS_EMPTY(alloc));
+
+    FREE(alloc, block);
+
+    ASSERT(tcs, no_threads == TEST_NO_THREADS);
+}
diff --git a/erts/emulator/test/alloc_SUITE_data/rbtree.c b/erts/emulator/test/alloc_SUITE_data/rbtree.c
index 4e7f821baf..702f075304 100644
--- a/erts/emulator/test/alloc_SUITE_data/rbtree.c
+++ b/erts/emulator/test/alloc_SUITE_data/rbtree.c
@@ -85,7 +85,7 @@ print_tree(TestCaseState_t *tcs, RBT_t *root)
 static RBT_t *
 check_tree(TestCaseState_t *tcs, Allctr_t *alc, Ulong size)
 {
-    enum { BF, AOBF, AOFF }type;
+    enum { BF, AOBF, AOFF, AOFFCAOBF }type;
     int i, max_i;
     char stk[128];
     RBT_t *root, *x, *y, *res;
@@ -94,11 +94,16 @@ check_tree(TestCaseState_t *tcs, Allctr_t *alc, Ulong size)
 
     res = NULL;
 
-    if      (IS_AOBF(alc)) type = AOBF;
-    else if (IS_AOFF(alc)) type = AOFF;
-    else type = BF;
+    if (IS_BF_ALGO(alc)) {
+	if (IS_AOBF(alc)) type = AOBF;
+	else type = BF;
+    }
+    else { /* AOFF_ALGO */
+	if (IS_CBF(alc)) type = AOFFCAOBF;
+	else type = AOFF;
+    }
 
-    root = RBT_ROOT(alc);
+    root = RBT_ROOT(alc, size);
 
 #ifdef PRINT_TREE
     print_tree(tcs, root);
@@ -188,6 +193,15 @@ check_tree(TestCaseState_t *tcs, Allctr_t *alc, Ulong size)
 		ASSERT(tcs, y < x);
 		ASSERT(tcs, RBT_MAX_SZ(y) <= RBT_MAX_SZ(x));
 		break;
+	    case AOFFCAOBF:
+		{
+		    void* x_crr = BLK_TO_MBC(x);
+		    void* y_crr = BLK_TO_MBC(y);
+		    ASSERT(tcs, (y < x && (x_crr != y_crr || x_sz == y_sz))
+			   || (y_sz < x_sz && x_crr == y_crr));
+		    ASSERT(tcs, RBT_MAX_SZ(y) <= RBT_MAX_SZ(x));
+		    break;
+		}
 	    }
 	}
 
@@ -207,6 +221,15 @@ check_tree(TestCaseState_t *tcs, Allctr_t *alc, Ulong size)
 		ASSERT(tcs, y > x);
 		ASSERT(tcs, RBT_MAX_SZ(y) <= RBT_MAX_SZ(x));
 		break;
+	    case AOFFCAOBF:
+		{
+		    void* x_crr = BLK_TO_MBC(x);
+		    void* y_crr = BLK_TO_MBC(y);
+		    ASSERT(tcs, (y > x && (x_crr != y_crr || x_sz == y_sz))
+			   || (y_sz > x_sz && x_crr == y_crr));
+		    ASSERT(tcs, RBT_MAX_SZ(y) <= RBT_MAX_SZ(x));
+		    break;
+		}
 	    }
 	}
 
@@ -239,7 +262,18 @@ check_tree(TestCaseState_t *tcs, Allctr_t *alc, Ulong size)
 			res = x;
 		    }
 		    break;
+		case AOFFCAOBF:
+		    if (BLK_TO_MBC(x) != BLK_TO_MBC(res) || x_sz == y_sz) {
+			if (x < res) {
+			    res = x;
+			}
+		    }
+		    else if (x_sz < y_sz) {
+			res = x;
+		    }
+		    break;
 		}
+
 	    }
 	}
 
@@ -263,17 +297,20 @@ check_tree(TestCaseState_t *tcs, Allctr_t *alc, Ulong size)
 }
 
 static void
-do_check(TestCaseState_t *tcs, Allctr_t *a, Ulong size)
+do_check(TestCaseState_t *tcs, Allctr_t *a, Ulong size, int ignore_null)
 {
     Ulong sz = ((size + 7) / 8)*8;
     void *tmp;
     Block_t *x, *y;
 
     x = (Block_t *) check_tree(tcs, a, sz);
+    if (!x && ignore_null)
+	return;
+
     tmp = ALLOC(a, sz - ABLK_HDR_SZ);
     ASSERT(tcs, tmp);
     y = UMEM2BLK(tmp);
-    if (IS_AOBF(a)) {
+    if (!(IS_BF_ALGO(a) && !IS_AOBF(a))) {
 	ASSERT(tcs, x == y);
     }
     else {
@@ -306,7 +343,7 @@ test_it(TestCaseState_t *tcs)
 	    blk[i] = NULL;
 	}
 	if (i % (NO_BLOCKS/2) == 0)
-	    do_check(tcs, a, 50);
+	    do_check(tcs, a, 50, 0);
     }
 
     for (i = 0; i < NO_BLOCKS; i++) {
@@ -315,7 +352,7 @@ test_it(TestCaseState_t *tcs)
 	    blk[i] = NULL;
 	}
 	if (i % (NO_BLOCKS/2) == 0)
-	    do_check(tcs, a, 200);
+	    do_check(tcs, a, 200, 0);
     }
 
     for (i = 0; i < NO_BLOCKS; i++) {
@@ -324,20 +361,101 @@ test_it(TestCaseState_t *tcs)
 	    blk[i] = NULL;
 	}
 	if (i % (NO_BLOCKS/2) == 0)
-	    do_check(tcs, a, 100);
+	    do_check(tcs, a, 100, 0);
     }
 
-    do_check(tcs, a, 250);
+    do_check(tcs, a, 250, 0);
 
     for (i = 0; i < NO_BLOCKS; i++) {
 	FREE(a, fence[i]);
 	if (i % (NO_BLOCKS/3) == 0)
-	    do_check(tcs, a, 300);
+	    do_check(tcs, a, 300, 0);
+    }
+
+    ASSERT(tcs, RBT_ROOT(a,0));
+    ASSERT(tcs, !RBT_LEFT(RBT_ROOT(a,0)));
+    ASSERT(tcs, !RBT_RIGHT(RBT_ROOT(a,0)));
+}
+
+
+static int is_single_ablk_in_mbc(Allctr_t* a, void* ptr, void* crr)
+{
+    Block_t* blk = UMEM2BLK(ptr);
+    if (crr == BLK_TO_MBC(blk)) {
+	Block_t* first = MBC_TO_FIRST_BLK(a, crr);
+	if (blk == first || (IS_FREE_BLK(first) && blk == NXT_BLK(first))) {
+	    Block_t* nxt;
+	    if (IS_LAST_BLK(blk)) {
+		return 1;
+	    }
+	    nxt = NXT_BLK(blk);
+	    return IS_FREE_BLK(nxt) && IS_LAST_BLK(nxt);
+	}
+    }
+    return 0;
+}
+
+static void
+test_carrier_migration(TestCaseState_t *tcs)
+{
+    int i, j;
+    Allctr_t* a = ((rbtree_test_data *) tcs->extra)->allocator;
+    void **blk = ((rbtree_test_data *) tcs->extra)->blk;
+    void **fence = ((rbtree_test_data *) tcs->extra)->fence;
+    void *crr, *p, *free_crr;
+    Ulong min_blk_sz;
+
+    min_blk_sz = MIN_BLK_SZ(a);
+
+    for (i = 0; i < NO_BLOCKS; i++) {
+	blk[i] = ALLOC(a, min_blk_sz + i % 500);
+	fence[i] = ALLOC(a, 1);
+	ASSERT(tcs, blk[i] && fence[i]);
+    }
+
+    for (j = 0; j < NO_BLOCKS; j += 997) {
+	crr = BLK_TO_MBC(UMEM2BLK(blk[j]));
+	REMOVE_MBC(a, crr);
+
+	for (i = 0; i < NO_BLOCKS; i++) {
+	    if (i % 3 == 0) {
+		if (is_single_ablk_in_mbc(a, blk[i], crr)) {
+		    crr = NULL; /* about to destroy the removed mbc */
+		}
+		FREE(a, blk[i]);
+		blk[i] = NULL;
+	    }
+	    if (i % (NO_BLOCKS/2) == 0)
+		do_check(tcs, a, 50, 1);
+	}
+	
+	for (i = 0; i < NO_BLOCKS; i++) {
+	    if (i % 3 == 0) {
+		ASSERT(tcs, !blk[i]);
+		blk[i] = ALLOC(a, min_blk_sz + i % 500);
+		ASSERT(tcs, BLK_TO_MBC(UMEM2BLK(blk[i])) != crr);
+	    }
+	    if (i % (NO_BLOCKS/2) == 0)
+		do_check(tcs, a, 50, 1);
+	}
+	if (crr) {
+	    ADD_MBC(a, crr);
+	}
+    }
+	
+    for (crr = FIRST_MBC(a); crr; crr = NEXT_C(crr)) {
+	REMOVE_MBC(a, crr);
     }
 
-    ASSERT(tcs, RBT_ROOT(a));
-    ASSERT(tcs, !RBT_LEFT(RBT_ROOT(a)));
-    ASSERT(tcs, !RBT_RIGHT(RBT_ROOT(a)));
+    p = ALLOC(a, 1);
+    free_crr = BLK_TO_MBC(UMEM2BLK(p));
+    FREE(a, p);
+
+    for (crr = FIRST_MBC(a); crr; crr = NEXT_C(crr)) {
+	ASSERT(tcs, free_crr != crr);
+    }
+
+    ASSERT(tcs, !RBT_ROOT(a,0));
 }
 
 
@@ -369,6 +487,7 @@ testcase_run(TestCaseState_t *tcs)
     char *argv1[] = {"-tasbf", NULL};
     char *argv2[] = {"-tasaobf", NULL};
     char *argv3[] = {"-tasaoff", NULL};
+    char *argv4[] = {"-tasaoffcaobf", NULL};
     Allctr_t *a;
     rbtree_test_data *td;
 
@@ -390,6 +509,7 @@ testcase_run(TestCaseState_t *tcs)
     td->allocator = a = START_ALC("rbtree_bf_", 0, argv1);
 
     ASSERT(tcs, a);
+    ASSERT(tcs, IS_BF_ALGO(a));
     ASSERT(tcs, !IS_AOBF(a));
 
     test_it(tcs);
@@ -407,6 +527,7 @@ testcase_run(TestCaseState_t *tcs)
     td->allocator = a = START_ALC("rbtree_aobf_", 0, argv2);
 
     ASSERT(tcs, a);
+    ASSERT(tcs, IS_BF_ALGO(a));
     ASSERT(tcs, IS_AOBF(a));
 
     test_it(tcs);
@@ -424,11 +545,34 @@ testcase_run(TestCaseState_t *tcs)
     td->allocator = a = START_ALC("rbtree_aoff_", 0, argv3);
 
     ASSERT(tcs, a);
+    ASSERT(tcs, !IS_BF_ALGO(a));
+    ASSERT(tcs, !IS_CBF(a));
 
     test_it(tcs);
+    test_carrier_migration(tcs);
 
     STOP_ALC(a);
     td->allocator = NULL;
 
     testcase_printf(tcs, "Address order first fit test succeeded!\n");
+
+    /* Address order first fit, best fit within carrier */
+
+    testcase_printf(tcs, "Starting test of aoffcaobf...\n");
+
+    current_rbt_type_op_base = AO_FIRSTFIT_OP_BASE;
+    td->allocator = a = START_ALC("rbtree_aoffcaobf_", 0, argv4);
+
+    ASSERT(tcs, a);
+    ASSERT(tcs, !IS_BF_ALGO(a));
+    ASSERT(tcs, IS_CBF(a));
+
+    test_it(tcs);
+    test_carrier_migration(tcs);
+
+    STOP_ALC(a);
+    td->allocator = NULL;
+
+    testcase_printf(tcs, "aoffcaobf test succeeded!\n");
+
 }
diff --git a/erts/emulator/test/driver_SUITE.erl b/erts/emulator/test/driver_SUITE.erl
index dfba7d098f..104bdf8aec 100644
--- a/erts/emulator/test/driver_SUITE.erl
+++ b/erts/emulator/test/driver_SUITE.erl
@@ -2582,10 +2582,9 @@ driver_alloc_size() ->
 	MemInfo ->
 	    CS = lists:foldl(
 		   fun ({instance, _, L}, Acc) ->
-			   {value,{_,SBMBCS}} = lists:keysearch(sbmbcs, 1, L),
 			   {value,{_,MBCS}} = lists:keysearch(mbcs, 1, L),
 			   {value,{_,SBCS}} = lists:keysearch(sbcs, 1, L),
-			   [SBMBCS,MBCS,SBCS | Acc]
+			   [MBCS,SBCS | Acc]
 		   end,
 		   [],
 		   MemInfo),
diff --git a/erts/emulator/test/nif_SUITE.erl b/erts/emulator/test/nif_SUITE.erl
index dcf58fa474..9a70e8646a 100644
--- a/erts/emulator/test/nif_SUITE.erl
+++ b/erts/emulator/test/nif_SUITE.erl
@@ -1368,10 +1368,9 @@ tmpmem() ->
 	MemInfo ->
 	    MSBCS = lists:foldl(
 		      fun ({instance, _, L}, Acc) ->
-			      {value,{_,SBMBCS}} = lists:keysearch(sbmbcs, 1, L),
 			      {value,{_,MBCS}} = lists:keysearch(mbcs, 1, L),
 			      {value,{_,SBCS}} = lists:keysearch(sbcs, 1, L),
-			      [SBMBCS,MBCS,SBCS | Acc]
+			      [MBCS,SBCS | Acc]
 		      end,
 		      [],
 		      MemInfo),
diff --git a/erts/emulator/test/send_term_SUITE.erl b/erts/emulator/test/send_term_SUITE.erl
index ba0ba804ca..6615873392 100644
--- a/erts/emulator/test/send_term_SUITE.erl
+++ b/erts/emulator/test/send_term_SUITE.erl
@@ -175,10 +175,6 @@ chk_temp_alloc() ->
 	    %% Verify that we havn't got anything allocated by temp_alloc
 	    lists:foreach(
 	      fun ({instance, _, TI}) ->
-		      ?line {value, {sbmbcs, SBMBCInfo}}
-			  = lists:keysearch(sbmbcs, 1, TI),
-		      ?line {value, {blocks, 0, _, _}}
-			  = lists:keysearch(blocks, 1, SBMBCInfo),
 		      ?line {value, {mbcs, MBCInfo}}
 			  = lists:keysearch(mbcs, 1, TI),
 		      ?line {value, {blocks, 0, _, _}}
diff --git a/erts/etc/common/erlexec.c b/erts/etc/common/erlexec.c
index 31d9b2e0ad..01134dd718 100644
--- a/erts/etc/common/erlexec.c
+++ b/erts/etc/common/erlexec.c
@@ -64,7 +64,6 @@
 static const char plusM_au_allocs[]= {
     'u',	/* all alloc_util allocators */
     'B',	/* binary_alloc		*/
-    'C',	/* sbmbc_alloc		*/
     'D',	/* std_alloc		*/
     'E',	/* ets_alloc		*/
     'F',	/* fix_alloc		*/
@@ -80,6 +79,7 @@ static const char plusM_au_allocs[]= {
 static char *plusM_au_alloc_switches[] = {
     "as",
     "asbcst",
+    "acul",
     "e",
     "t",
     "lmbcs",
@@ -95,8 +95,6 @@ static char *plusM_au_alloc_switches[] = {
     "rsbcst",
     "sbct",
     "smbcs",
-    "sbmbcs",
-    "sbmbct",
     NULL
 };
 
diff --git a/erts/preloaded/ebin/erlang.beam b/erts/preloaded/ebin/erlang.beam
index 226e4c8a1f..5a0bb637cc 100644
--- a/erts/preloaded/ebin/erlang.beam
+++ b/erts/preloaded/ebin/erlang.beam
diff --git a/erts/preloaded/src/erlang.erl b/erts/preloaded/src/erlang.erl
index 0df0768365..fb869bae66 100644
--- a/erts/preloaded/src/erlang.erl
+++ b/erts/preloaded/src/erlang.erl
@@ -3114,8 +3114,8 @@ max(A, _) -> A.
                      | 'atom' | 'atom_used' | 'binary' | 'code' | 'ets'
                      | 'low' | 'maximum'.
 
--define(CARRIER_ALLOCS, [mseg_alloc, sbmbc_alloc, sbmbc_low_alloc]).
--define(LOW_ALLOCS, [sbmbc_low_alloc, ll_low_alloc, std_low_alloc]).
+-define(CARRIER_ALLOCS, [mseg_alloc]).
+-define(LOW_ALLOCS, [ll_low_alloc, std_low_alloc]).
 -define(ALL_NEEDED_ALLOCS, (erlang:system_info(alloc_util_allocators)
 			    -- ?CARRIER_ALLOCS)).
 
@@ -3282,12 +3282,16 @@ get_blocks_size([{blocks_size, Sz, _, _} | Rest], Acc) ->
     get_blocks_size(Rest, Acc+Sz);
 get_blocks_size([{_, _, _, _} | Rest], Acc) ->
     get_blocks_size(Rest, Acc);
+get_blocks_size([{blocks_size, Sz} | Rest], Acc) ->
+    get_blocks_size(Rest, Acc+Sz);
+get_blocks_size([{_, _} | Rest], Acc) ->
+    get_blocks_size(Rest, Acc);
 get_blocks_size([], Acc) ->
     Acc.
 
 blocks_size([{Carriers, SizeList} | Rest], Acc) when Carriers == mbcs;
-						     Carriers == sbcs;
-						     Carriers == sbmbcs ->
+						     Carriers == mbcs_pool;
+						     Carriers == sbcs ->
     blocks_size(Rest, get_blocks_size(SizeList, Acc));
 blocks_size([_ | Rest], Acc) ->
     blocks_size(Rest, Acc);
@@ -3306,6 +3310,9 @@ get_fix_proc([], Acc) ->
 
 fix_proc([{fix_types, SizeList} | _Rest], Acc) ->
     get_fix_proc(SizeList, Acc);
+fix_proc([{fix_types, Mask, SizeList} | _Rest], Acc) ->
+    {A, U} = get_fix_proc(SizeList, Acc),
+    {Mask, A, U};
 fix_proc([_ | Rest], Acc) ->
     fix_proc(Rest, Acc);
 fix_proc([], Acc) ->
@@ -3357,13 +3364,21 @@ au_mem_data(#memory{total = Tot,
 		    processes_used = ProcU,
 		    system = Sys} = Mem,
 	    [{fix_alloc, _, Data} | Rest]) ->
-    {A, U} = fix_proc(Data, {0, 0}),
     Sz = blocks_size(Data, 0),
-    au_mem_data(Mem#memory{total = Tot+Sz,
-			   processes = Proc+A,
-			   processes_used = ProcU+U,
-			   system = Sys+Sz-A},
-		Rest);
+    case fix_proc(Data, {0, 0}) of
+	{A, U} ->
+	    au_mem_data(Mem#memory{total = Tot+Sz,
+				   processes = Proc+A,
+				   processes_used = ProcU+U,
+				   system = Sys+Sz-A},
+			Rest);
+	{Mask, A, U} ->
+	    au_mem_data(Mem#memory{total = Tot+Sz,
+				   processes = Mask band (Proc+A),
+				   processes_used = Mask band (ProcU+U),
+				   system = Mask band (Sys+Sz-A)},
+			Rest)
+    end;
 au_mem_data(#memory{total = Tot,
 		    system = Sys,
 		    low = Low} = Mem,
@@ -3381,7 +3396,7 @@ au_mem_data(EMD, []) ->
 
 au_mem_data(Allocs) ->
     Ref = erlang:make_ref(),
-    erlang:system_info({allocator_sizes, Ref, Allocs}),
+    erlang:system_info({memory_internal, Ref, Allocs}),
     receive_emd(Ref).
 
 receive_emd(_Ref, EMD, 0) ->
diff --git a/lib/stdlib/test/ets_SUITE.erl b/lib/stdlib/test/ets_SUITE.erl
index 85bd82a854..41449a1071 100644
--- a/lib/stdlib/test/ets_SUITE.erl
+++ b/lib/stdlib/test/ets_SUITE.erl
@@ -5675,10 +5675,9 @@ etsmem() ->
 	 MemInfo ->
 	     CS = lists:foldl(
 		    fun ({instance, _, L}, Acc) ->
-			    {value,{_,SBMBCS}} = lists:keysearch(sbmbcs, 1, L),
 			    {value,{_,MBCS}} = lists:keysearch(mbcs, 1, L),
 			    {value,{_,SBCS}} = lists:keysearch(sbcs, 1, L),
-			    [SBMBCS,MBCS,SBCS | Acc]
+			    [MBCS,SBCS | Acc]
 		    end,
 		    [],
 		    MemInfo),