Merge branch 'maint-20' into maint

* maint-20:
  Updated OTP version
  Update release notes
  Update version numbers
  erts: Add system_flags(erts_alloc,"+M?sbct *")
  erts: Add age order first fit allocator strategies
  erts: Refactor erl_ao_firstfit_alloc
  erts: Add migration options "acnl" and "acfml"
  kernel: Add os:cmd/2 with max_size option
  erts: Add more stats for mbcs_pool
  erts: Fix alloc_SUITE:migration
  stdlib: Make ets_SUITE memory check try again
  erts: Improve carrier pool search
  erts: Improve alloc_SUITE:migration
  erts: Refactor carrier dealloc migration

9 files changed, 983 insertions, 562 deletions

diff --git a/erts/emulator/beam/atom.names b/erts/emulator/beam/atom.names
index a44d23b181..7b12e5432d 100644
--- a/erts/emulator/beam/atom.names
+++ b/erts/emulator/beam/atom.names
@@ -578,7 +578,8 @@ atom running_procs
 atom runtime
 atom safe
 atom save_calls
-atom scheduler
+atom sbct
+atom scheduler 
 atom scheduler_id
 atom scheduler_wall_time
 atom scheduler_wall_time_all
diff --git a/erts/emulator/beam/bif.c b/erts/emulator/beam/bif.c
index b6595d2a5d..d7a25adccb 100644
--- a/erts/emulator/beam/bif.c
+++ b/erts/emulator/beam/bif.c
@@ -4905,6 +4905,8 @@ BIF_RETTYPE system_flag_2(BIF_ALIST_2)
 	    "scheduled for removal in Erlang/OTP 18. For more\n"
 	    "information see the erlang:system_flag/2 documentation.\n");
 	return erts_bind_schedulers(BIF_P, BIF_ARG_2);
+    } else if (ERTS_IS_ATOM_STR("erts_alloc", BIF_ARG_1)) {
+        return erts_alloc_set_dyn_param(BIF_P, BIF_ARG_2);
     }
     error:
     BIF_ERROR(BIF_P, BADARG);
diff --git a/erts/emulator/beam/erl_alloc.c b/erts/emulator/beam/erl_alloc.c
index c7ab444c96..928a91baf4 100644
--- a/erts/emulator/beam/erl_alloc.c
+++ b/erts/emulator/beam/erl_alloc.c
@@ -168,7 +168,7 @@ enum allctr_type {
     GOODFIT,
     BESTFIT,
     AFIT,
-    AOFIRSTFIT
+    FIRSTFIT
 };
 
 struct au_init {
@@ -507,8 +507,9 @@ set_default_test_alloc_opts(struct au_init *ip)
     SET_DEFAULT_ALLOC_OPTS(ip);
     ip->enable			= 0; /* Disabled by default */
     ip->thr_spec		= -1 * erts_no_schedulers;
-    ip->atype			= AOFIRSTFIT;
-    ip->init.aoff.flavor        = AOFF_BF;
+    ip->atype			= FIRSTFIT;
+    ip->init.aoff.crr_order     = FF_AOFF;
+    ip->init.aoff.blk_order     = FF_BF;
     ip->init.util.name_prefix	= "test_";
     ip->init.util.alloc_no	= ERTS_ALC_A_TEST;
     ip->init.util.mmbcs 	= 0; /* Main carrier size */
@@ -610,10 +611,10 @@ static ERTS_INLINE int
 strategy_support_carrier_migration(struct au_init *auip)
 {
     /*
-     * Currently only aoff, aoffcbf and aoffcaobf support carrier
+     * Currently only aoff* and ageff* support carrier
      * migration, i.e, type AOFIRSTFIT.
      */
-    return auip->atype == AOFIRSTFIT;
+    return auip->atype == FIRSTFIT;
 }
 
 static ERTS_INLINE void
@@ -629,8 +630,9 @@ adjust_carrier_migration_support(struct au_init *auip)
 	 */
 	if (!strategy_support_carrier_migration(auip)) {
 	    /* Default to aoffcbf */
-	    auip->atype = AOFIRSTFIT;
-	    auip->init.aoff.flavor = AOFF_BF;
+	    auip->atype = FIRSTFIT;
+	    auip->init.aoff.crr_order = FF_AOFF;
+	    auip->init.aoff.blk_order = FF_BF;
 	}
     }
 #else
@@ -1187,7 +1189,7 @@ start_au_allocator(ErtsAlcType_t alctr_n,
 					   &init->init.af,
 					   &init->init.util);
 	    break;
-    	case AOFIRSTFIT:
+	case FIRSTFIT:
 	    as = erts_aoffalc_start((AOFFAllctr_t *) as0,
 					     &init->init.aoff,
 					     &init->init.util);
@@ -1281,22 +1283,32 @@ get_bool_value(char *param_end, char** argv, int* ip)
     return -1;
 }
 
+static Uint kb_to_bytes(Sint kb, Uint *bytes)
+{
+    const Uint max = ((~((Uint) 0))/1024) + 1;
+
+    if (kb < 0 || (Uint)kb > max)
+        return 0;
+    if ((Uint)kb == max)
+        *bytes = ~((Uint) 0);
+    else
+        *bytes = ((Uint) kb)*1024;
+    return 1;
+}
+
 static Uint
 get_kb_value(char *param_end, char** argv, int* ip)
 {
     Sint tmp;
-    Uint max = ((~((Uint) 0))/1024) + 1;
+    Uint bytes = 0;
     char *rest;
     char *param = argv[*ip]+1;
     char *value = get_value(param_end, argv, ip);
     errno = 0;
     tmp = (Sint) ErtsStrToSint(value, &rest, 10);
-    if (errno != 0 || rest == value || tmp < 0 || max < ((Uint) tmp))
+    if (errno != 0 || rest == value || !kb_to_bytes(tmp, &bytes))
 	bad_value(param, param_end, value);
-    if (max == (Uint) tmp)
-	return ~((Uint) 0);
-    else
-	return ((Uint) tmp)*1024;
+    return bytes;
 }
 
 static UWord
@@ -1383,18 +1395,30 @@ handle_au_arg(struct au_init *auip,
 
     switch (sub_param[0]) {
     case 'a':
-	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;
-		}
-	    }
-	    auip->init.util.acul = get_acul_value(auip, sub_param + 4, argv, ip);
-	}
+        if (sub_param[1] == 'c') { /* Migration parameters "ac*" */
+            UWord value;
+            UWord* wp;
+            if (!auip->carrier_migration_allowed && !u_switch)
+                goto bad_switch;
+
+            if (has_prefix("acul", sub_param)) {
+                value = get_acul_value(auip, sub_param + 4, argv, ip);
+                wp = &auip->init.util.acul;
+            }
+            else if (has_prefix("acnl", sub_param)) {
+                value = get_amount_value(sub_param + 4, argv, ip);
+                wp = &auip->init.util.acnl;
+            }
+            else if (has_prefix("acfml", sub_param)) {
+                value = get_amount_value(sub_param + 5, argv, ip);
+                wp = &auip->init.util.acfml;
+            }
+            else
+                goto bad_switch;
+
+            if (auip->carrier_migration_allowed)
+                *wp = value;
+        }
 	else if(has_prefix("asbcst", sub_param)) {
 	    auip->init.util.asbcst = get_kb_value(sub_param + 6, argv, ip);
 	}
@@ -1415,17 +1439,35 @@ handle_au_arg(struct au_init *auip,
 		auip->atype = AFIT;
 	    }
 	    else if (strcmp("aoff", alg) == 0) {
-		auip->atype = AOFIRSTFIT;
-		auip->init.aoff.flavor = AOFF_AOFF;
+		auip->atype = FIRSTFIT;
+		auip->init.aoff.crr_order = FF_AOFF;
+		auip->init.aoff.blk_order = FF_AOFF;
 	    }
 	    else if (strcmp("aoffcbf", alg) == 0) {
-		auip->atype = AOFIRSTFIT;
-		auip->init.aoff.flavor = AOFF_BF;
+		auip->atype = FIRSTFIT;
+		auip->init.aoff.crr_order = FF_AOFF;
+		auip->init.aoff.blk_order = FF_BF;
 	    }
 	    else if (strcmp("aoffcaobf", alg) == 0) {
-		auip->atype = AOFIRSTFIT;
-		auip->init.aoff.flavor = AOFF_AOBF;
+		auip->atype = FIRSTFIT;
+		auip->init.aoff.crr_order = FF_AOFF;
+		auip->init.aoff.blk_order = FF_AOBF;
 	    }
+            else if (strcmp("ageffcaoff", alg) == 0) {
+                auip->atype = FIRSTFIT;
+		auip->init.aoff.crr_order = FF_AGEFF;
+		auip->init.aoff.blk_order = FF_AOFF;
+            }
+            else if (strcmp("ageffcbf", alg) == 0) {
+                auip->atype = FIRSTFIT;
+		auip->init.aoff.crr_order = FF_AGEFF;
+		auip->init.aoff.blk_order = FF_BF;
+            }
+            else if (strcmp("ageffcaobf", alg) == 0) {
+                auip->atype = FIRSTFIT;
+		auip->init.aoff.crr_order = FF_AGEFF;
+		auip->init.aoff.blk_order = FF_AOBF;
+            }
 	    else {
 		bad_value(param, sub_param + 1, alg);
 	    }
@@ -3464,6 +3506,65 @@ erts_request_alloc_info(struct process *c_p,
     return 1;
 }
 
+Eterm erts_alloc_set_dyn_param(Process* c_p, Eterm tuple)
+{
+    ErtsAllocatorThrSpec_t *tspec;
+    ErtsAlcType_t ai;
+    Allctr_t* allctr;
+    Eterm* tp;
+    Eterm res;
+
+    if (!is_tuple_arity(tuple, 3))
+        goto badarg;
+
+    tp = tuple_val(tuple);
+
+    /*
+     * Ex: {ets_alloc, sbct, 256000}
+     */
+    if (!is_atom(tp[1]) || !is_atom(tp[2]) || !is_integer(tp[3]))
+        goto badarg;
+
+    for (ai = ERTS_ALC_A_MIN; ai <= ERTS_ALC_A_MAX; ai++)
+        if (erts_is_atom_str(erts_alc_a2ad[ai], tp[1], 0))
+            break;
+
+    if (ai > ERTS_ALC_A_MAX)
+        goto badarg;
+
+    if (!erts_allctrs_info[ai].enabled ||
+        !erts_allctrs_info[ai].alloc_util) {
+        return am_notsup;
+    }
+
+    if (tp[2] == am_sbct) {
+        Uint sbct;
+        int i, ok;
+
+        if (!term_to_Uint(tp[3], &sbct))
+            goto badarg;
+
+        tspec = &erts_allctr_thr_spec[ai];
+        if (tspec->enabled) {
+            ok = 0;
+            for (i = 0; i < tspec->size; i++) {
+                allctr = tspec->allctr[i];
+                ok |= allctr->try_set_dyn_param(allctr, am_sbct, sbct);
+            }
+        }
+        else {
+            allctr = erts_allctrs_info[ai].extra;
+            ok = allctr->try_set_dyn_param(allctr, am_sbct, sbct);
+        }
+        return ok ? am_ok : am_notsup;
+    }
+    return am_notsup;
+
+badarg:
+    ERTS_BIF_PREP_ERROR(res, c_p, EXC_BADARG);
+    return res;
+}
+
 /* 
  * The allocator wrapper prelocking stuff below is about the locking order.
  * It only affects wrappers (erl_mtrace.c and erl_instrument.c) that keep locks
@@ -3610,7 +3711,7 @@ UWord erts_alc_test(UWord op, UWord a1, UWord a2, UWord a3)
 					  &init.init.af,
 					  &init.init.util);
 		break;
-	    case AOFIRSTFIT:
+	    case FIRSTFIT:
 		allctr = erts_aoffalc_start((AOFFAllctr_t *)
 					  erts_alloc(ERTS_ALC_T_UNDEF,
 						     sizeof(AOFFAllctr_t)),
@@ -3710,7 +3811,9 @@ UWord erts_alc_test(UWord op, UWord a1, UWord a2, UWord a3)
 
 	case 0xf15: erts_free(ERTS_ALC_T_TEST, (void*)a1); return 0;
 
-	case 0xf16: {
+        case 0xf16: return (UWord) erts_realloc(ERTS_ALC_T_TEST, (void*)a1, (Uint)a2);
+
+	case 0xf17: {
             Uint extra_hdr_sz = UNIT_CEILING((Uint)a1);
 	    ErtsAllocatorThrSpec_t* ts = &erts_allctr_thr_spec[ERTS_ALC_A_TEST];
 	    Uint offset = ts->allctr[0]->mbc_header_size;
@@ -3737,7 +3840,7 @@ UWord erts_alc_test(UWord op, UWord a1, UWord a2, UWord a3)
 	    *(void**)a3 = orig_destroying_mbc;
 	    return offset;
 	}
-	case 0xf17: {
+	case 0xf18: {
 	    ErtsAllocatorThrSpec_t* ts = &erts_allctr_thr_spec[ERTS_ALC_A_TEST];
 	    return ts->allctr[0]->largest_mbc_size;
 	}
diff --git a/erts/emulator/beam/erl_alloc.h b/erts/emulator/beam/erl_alloc.h
index 97a1cf1308..b7eb977317 100644
--- a/erts/emulator/beam/erl_alloc.h
+++ b/erts/emulator/beam/erl_alloc.h
@@ -173,6 +173,8 @@ __decl_noreturn void erts_realloc_n_enomem(ErtsAlcType_t,void*,Uint)
 __decl_noreturn void erts_alc_fatal_error(int,int,ErtsAlcType_t,...)	
      __noreturn;
 
+Eterm erts_alloc_set_dyn_param(struct process*, Eterm);
+
 #undef ERTS_HAVE_IS_IN_LITERAL_RANGE
 #if defined(ARCH_32) || defined(ERTS_HAVE_OS_PHYSICAL_MEMORY_RESERVATION)
 #  define ERTS_HAVE_IS_IN_LITERAL_RANGE
diff --git a/erts/emulator/beam/erl_alloc_util.c b/erts/emulator/beam/erl_alloc_util.c
index af86ad0548..ae4ff4f453 100644
--- a/erts/emulator/beam/erl_alloc_util.c
+++ b/erts/emulator/beam/erl_alloc_util.c
@@ -375,8 +375,10 @@ do {										\
 
 #define ERTS_CRR_ALCTR_FLG_IN_POOL	(((erts_aint_t) 1) << 0)
 #define ERTS_CRR_ALCTR_FLG_BUSY		(((erts_aint_t) 1) << 1)
+#define ERTS_CRR_ALCTR_FLG_HOMECOMING	(((erts_aint_t) 1) << 2)
 #define ERTS_CRR_ALCTR_FLG_MASK (ERTS_CRR_ALCTR_FLG_IN_POOL | \
-                                 ERTS_CRR_ALCTR_FLG_BUSY)
+                                 ERTS_CRR_ALCTR_FLG_BUSY |    \
+                                 ERTS_CRR_ALCTR_FLG_HOMECOMING)
 
 #ifdef ERTS_SMP
 #define SBC_HEADER_SIZE	   						\
@@ -583,7 +585,7 @@ do {									\
     DEBUG_CHECK_CARRIER_NO_SZ((AP));					\
 } while (0)
 
-#define STAT_MBC_CPOOL_INSERT(AP, CRR)					\
+#define STAT_MBC_ABANDON(AP, CRR)					\
 do {									\
     UWord csz__ = CARRIER_SZ((CRR));					\
     if (IS_MSEG_CARRIER((CRR)))						\
@@ -1189,90 +1191,25 @@ unlink_carrier(CarrierList_t *cl, Carrier_t *crr)
 	ASSERT(crr->next);
 	crr->next->prev = crr->prev;
     }
-}
-
-#ifdef ERTS_SMP
-
 #ifdef DEBUG
-static int is_in_list(ErtsDoubleLink_t* sentinel, ErtsDoubleLink_t* node)
-{
-    ErtsDoubleLink_t* p;
-
-    ASSERT(node != sentinel);
-    for (p = sentinel->next; p != sentinel; p = p->next) {
-	if (p == node)
-	    return 1;
-    }
-    return 0;
-}
-#endif /* DEBUG */
-
-static ERTS_INLINE void
-link_edl_after(ErtsDoubleLink_t* after_me, ErtsDoubleLink_t* node)
-{
-    ErtsDoubleLink_t* before_me = after_me->next;
-    ASSERT(node != after_me && node != before_me);
-    node->next = before_me;
-    node->prev = after_me;
-    before_me->prev = node;
-    after_me->next = node;
-}
-
-static ERTS_INLINE void
-link_edl_before(ErtsDoubleLink_t* before_me, ErtsDoubleLink_t* node)
-{
-    ErtsDoubleLink_t* after_me = before_me->prev;
-    ASSERT(node != before_me && node != after_me);
-    node->next = before_me;
-    node->prev = after_me;
-    before_me->prev = node;
-    after_me->next = node;
-}
-
-static ERTS_INLINE void
-unlink_edl(ErtsDoubleLink_t* node)
-{
-    node->next->prev = node->prev;
-    node->prev->next = node->next;
+    crr->next = crr;
+    crr->prev = crr;
+#endif
 }
 
-static ERTS_INLINE void
-relink_edl_before(ErtsDoubleLink_t* before_me, ErtsDoubleLink_t* node)
-{
-    if (node != before_me && node != before_me->prev) {
-	unlink_edl(node);
-	link_edl_before(before_me, node);
-    }
-}
+#ifdef ERTS_SMP
 
 static ERTS_INLINE int is_abandoned(Carrier_t *crr)
 {
-    return crr->cpool.abandoned.next != NULL;
-}
-
-static ERTS_INLINE void
-link_abandoned_carrier(ErtsDoubleLink_t* list, Carrier_t *crr)
-{
-    ASSERT(!is_abandoned(crr));
-
-    link_edl_after(list, &crr->cpool.abandoned);
-
-    ASSERT(crr->cpool.abandoned.next != &crr->cpool.abandoned);
-    ASSERT(crr->cpool.abandoned.prev != &crr->cpool.abandoned);
+    return crr->cpool.state != ERTS_MBC_IS_HOME;
 }
 
 static ERTS_INLINE void
 unlink_abandoned_carrier(Carrier_t *crr)
 {
-    ASSERT(is_in_list(&crr->cpool.orig_allctr->cpool.pooled_list,
-		      &crr->cpool.abandoned) ||
-	   is_in_list(&crr->cpool.orig_allctr->cpool.traitor_list,
-		      &crr->cpool.abandoned));
-
-    unlink_edl(&crr->cpool.abandoned);
-
-    crr->cpool.abandoned.next = NULL;
-    crr->cpool.abandoned.prev = NULL;
+    if (crr->cpool.state == ERTS_MBC_WAS_POOLED) {
+        aoff_remove_pooled_mbc(crr->cpool.orig_allctr, crr);
+    }
 }
 
 static ERTS_INLINE void
@@ -1280,24 +1217,19 @@ clear_busy_pool_carrier(Allctr_t *allctr, Carrier_t *crr)
 {
     if (crr) {
 	erts_aint_t max_size;
-	erts_aint_t new_val;
+	erts_aint_t iallctr;
 
 	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;
+        iallctr = erts_smp_atomic_read_nob(&crr->allctr);
+        ERTS_ALC_CPOOL_ASSERT((iallctr & ~ERTS_CRR_ALCTR_FLG_HOMECOMING)
+                              == ((erts_aint_t)allctr |
+                                  ERTS_CRR_ALCTR_FLG_IN_POOL |
+                                  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
+	iallctr &= ~ERTS_CRR_ALCTR_FLG_BUSY;
+	erts_smp_atomic_set_relb(&crr->allctr, iallctr);
     }
 }
 
@@ -1711,6 +1643,11 @@ dealloc_mbc(Allctr_t *allctr, Carrier_t *crr)
 
 #ifdef ERTS_SMP
 
+static void set_new_allctr_abandon_limit(Allctr_t*);
+static void abandon_carrier(Allctr_t*, Carrier_t*);
+static void poolify_my_carrier(Allctr_t*, Carrier_t*);
+static void enqueue_homecoming(Allctr_t*, Carrier_t*);
+
 static ERTS_INLINE Allctr_t*
 get_pref_allctr(void *extra)
 {
@@ -1777,9 +1714,23 @@ get_used_allctr(Allctr_t *pref_allctr, int pref_lock, void *p, UWord *sizep,
 		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 (iallctr & ERTS_CRR_ALCTR_FLG_HOMECOMING) {
+                    /*
+                     * This carrier has just been given back to us by writing
+                     * to crr->allctr with a write barrier (see abandon_carrier).
+                     *
+                     * We need a mathing read barrier to guarantee a correct view
+                     * of the carrier for deallocation work.
+                     */
+                    act = erts_smp_atomic_cmpxchg_rb(&crr->allctr,
+                                                     iallctr|ERTS_CRR_ALCTR_FLG_BUSY,
+                                                     iallctr);
+                }
+                else {
+                    act = erts_smp_atomic_cmpxchg_ddrb(&crr->allctr,
+                                                       iallctr|ERTS_CRR_ALCTR_FLG_BUSY,
+                                                       iallctr);
+                }
 		if (act == iallctr) {
 		    *busy_pcrr_pp = crr;
 		    break;
@@ -1795,13 +1746,6 @@ get_used_allctr(Allctr_t *pref_allctr, int pref_lock, void *p, UWord *sizep,
 		    erts_mtx_unlock(&pref_allctr->mutex);
 		}
 	    }
-
-	    ERTS_ALC_CPOOL_ASSERT(
-		(((iallctr & ~ERTS_CRR_ALCTR_FLG_MASK) == (erts_aint_t) pref_allctr)
-		 ? (((iallctr & ERTS_CRR_ALCTR_FLG_MASK) == ERTS_CRR_ALCTR_FLG_IN_POOL)
-		    || ((iallctr & ERTS_CRR_ALCTR_FLG_MASK) == 0))
-		 : 1));
-
 	    return used_allctr;
 	}
     }
@@ -2053,9 +1997,9 @@ handle_delayed_fix_dealloc(Allctr_t *allctr, void *ptr)
 	    /* 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);
+            ERTS_ALC_CPOOL_ASSERT(!busy_pcrr_p);
 
-	    DEC_CC(allctr->calls.this_free);
+            DEC_CC(allctr->calls.this_free);
 
 	    ((ErtsAllctrFixDDBlock_t *) ptr)->fix_type = type;
 	    if (ddq_enqueue(&used_allctr->dd.q, ptr, cinit))
@@ -2064,8 +2008,9 @@ handle_delayed_fix_dealloc(Allctr_t *allctr, void *ptr)
     }
 }
 
-static void
-schedule_dealloc_carrier(Allctr_t *allctr, Carrier_t *crr);
+static void schedule_dealloc_carrier(Allctr_t*, Carrier_t*);
+static void dealloc_my_carrier(Allctr_t*, Carrier_t*);
+
 
 static ERTS_INLINE int
 handle_delayed_dealloc(Allctr_t *allctr,
@@ -2127,39 +2072,61 @@ handle_delayed_dealloc(Allctr_t *allctr,
 	res = 1;
 
 	blk = UMEM2BLK(ptr);
-	if (IS_FREE_LAST_MBC_BLK(blk)) {
+	if (blk->bhdr == HOMECOMING_MBC_BLK_HDR) {
 	    /*
 	     * A multiblock carrier that previously has been migrated away
-	     * from us and now is back to be deallocated. For more info
-	     * see schedule_dealloc_carrier().
-	     *
-	     * Note that we cannot use FBLK_TO_MBC(blk) since it
-	     * data has been overwritten by the queue.
+             * from us, was sent back to us either because
+             * - it became empty and we need to deallocated it, or
+             * - it was inserted into the pool and we need to update our pooled_tree
 	     */
-	    Carrier_t *crr = FIRST_BLK_TO_MBC(allctr, blk);
-
-	     /* Restore word overwritten by the dd-queue as it will be read
-	      * if this carrier is pulled from dc_list by cpool_fetch()
-	      */
-	    ERTS_ALC_CPOOL_ASSERT(FBLK_TO_MBC(blk) != crr);
-	    ERTS_CT_ASSERT(sizeof(ErtsAllctrDDBlock_t) == sizeof(void*));
-#ifdef MBC_ABLK_OFFSET_BITS
-	    blk->u.carrier = crr;
-#else
-	    blk->carrier = crr;
-#endif
+	    Carrier_t *crr = ErtsContainerStruct(blk, Carrier_t,
+                                                 cpool.homecoming_dd.blk);
+            Block_t* first_blk = MBC_TO_FIRST_BLK(allctr, crr);
+            erts_aint_t iallctr;
 
 	    ERTS_ALC_CPOOL_ASSERT(ERTS_ALC_IS_CPOOL_ENABLED(allctr));
 	    ERTS_ALC_CPOOL_ASSERT(allctr == crr->cpool.orig_allctr);
-	    ERTS_ALC_CPOOL_ASSERT(((erts_aint_t) allctr)
-				  != (erts_smp_atomic_read_nob(&crr->allctr)
-				      & ~ERTS_CRR_ALCTR_FLG_MASK));
 
-	    erts_smp_atomic_set_nob(&crr->allctr, ((erts_aint_t) allctr));
-
-	    schedule_dealloc_carrier(allctr, crr);
+            iallctr = erts_smp_atomic_read_nob(&crr->allctr);
+            ASSERT(iallctr & ERTS_CRR_ALCTR_FLG_HOMECOMING);
+            while (1) {
+                if ((iallctr & (~ERTS_CRR_ALCTR_FLG_MASK |
+                                ERTS_CRR_ALCTR_FLG_IN_POOL))
+                    == (erts_aint_t)allctr) {
+                    /*
+                     * Carrier is home (mine and not in pool)
+                     */
+                    ASSERT(!(iallctr & ERTS_CRR_ALCTR_FLG_BUSY));
+                    erts_smp_atomic_set_nob(&crr->allctr, (erts_aint_t)allctr);
+                    if (IS_FREE_LAST_MBC_BLK(first_blk))
+                        dealloc_my_carrier(allctr, crr);
+                    else
+                        ASSERT(crr->cpool.state == ERTS_MBC_IS_HOME);
+                }
+                else {
+                    erts_aint_t exp = iallctr;
+                    erts_aint_t want = iallctr & ~ERTS_CRR_ALCTR_FLG_HOMECOMING;
+
+                    iallctr = erts_smp_atomic_cmpxchg_nob(&crr->allctr,
+                                                          want,
+                                                          exp);
+                    if (iallctr != exp)
+                        continue; /* retry */
+
+                    ASSERT(crr->cpool.state != ERTS_MBC_IS_HOME);
+                    unlink_abandoned_carrier(crr);
+                    if (iallctr & ERTS_CRR_ALCTR_FLG_IN_POOL)
+                        poolify_my_carrier(allctr, crr);
+                    else
+                        crr->cpool.state = ERTS_MBC_WAS_TRAITOR;
+                }
+                break;
+            }
 	}
 	else {
+            ASSERT(IS_SBC_BLK(blk) || (ABLK_TO_MBC(blk) !=
+                                       ErtsContainerStruct(blk, Carrier_t,
+                                                           cpool.homecoming_dd.blk)));
 
 	    INC_CC(allctr->calls.this_free);
 
@@ -2201,22 +2168,26 @@ enqueue_dealloc_other_instance(ErtsAlcType_t type,
 	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
+update_pooled_tree(Allctr_t *allctr, Carrier_t *crr, Uint blk_sz)
+{
+    if (allctr == crr->cpool.orig_allctr && crr->cpool.state == ERTS_MBC_WAS_POOLED) {
+	/*
+	 * Update pooled_tree with a potentially new (larger) max_sz
+         */
+        AOFF_RBTree_t* crr_node = &crr->cpool.pooled;
+        if (blk_sz > crr_node->hdr.bhdr) {
+            crr_node->hdr.bhdr = blk_sz;
+            erts_aoff_larger_max_size(crr_node);
+        }
+    }
+}
 
 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;
+    UWord ncrr_in_pool, largest_fblk;
 
     if (!ERTS_ALC_IS_CPOOL_ENABLED(allctr))
 	return;
@@ -2225,8 +2196,7 @@ check_abandon_carrier(Allctr_t *allctr, Block_t *fblk, Carrier_t **busy_pcrr_pp)
     if (--allctr->cpool.check_limit_count <= 0)
 	set_new_allctr_abandon_limit(allctr);
 
-    if (!erts_thr_progress_is_managed_thread())
-	return;
+    ASSERT(erts_thr_progress_is_managed_thread());
 
     if (allctr->cpool.disable_abandon)
 	return;
@@ -2234,6 +2204,9 @@ check_abandon_carrier(Allctr_t *allctr, Block_t *fblk, Carrier_t **busy_pcrr_pp)
     if (allctr->mbcs.blocks.curr.size > allctr->cpool.abandon_limit)
 	return;
 
+    ncrr_in_pool = erts_atomic_read_nob(&allctr->cpool.stat.no_carriers);
+    if (ncrr_in_pool >= allctr->cpool.in_pool_limit)
+        return;
 
     crr = FBLK_TO_MBC(fblk);
 
@@ -2244,9 +2217,14 @@ check_abandon_carrier(Allctr_t *allctr, Block_t *fblk, Carrier_t **busy_pcrr_pp)
 	return;
 
     if (crr->cpool.thr_prgr != ERTS_THR_PRGR_INVALID
-	&& !erts_thr_progress_has_reached(crr->cpool.thr_prgr))
-	return;
+        && !erts_thr_progress_has_reached(crr->cpool.thr_prgr))
+        return;
 
+    largest_fblk = allctr->largest_fblk_in_mbc(allctr, crr);
+    if (largest_fblk < allctr->cpool.fblk_min_limit)
+        return;
+
+    erts_atomic_set_nob(&crr->cpool.max_size, largest_fblk);
     abandon_carrier(allctr, crr);
 }
 
@@ -2299,6 +2277,7 @@ dealloc_block(Allctr_t *allctr, void *ptr, ErtsAlcFixList_t *fix, int dec_cc_on_
     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) {
@@ -2315,10 +2294,10 @@ dealloc_block(Allctr_t *allctr, void *ptr, ErtsAlcFixList_t *fix, int dec_cc_on_
 	    /* 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);
+            ERTS_ALC_CPOOL_ASSERT(!busy_pcrr_p);
 
-	    if (dec_cc_on_redirect)
-		DEC_CC(allctr->calls.this_free);
+            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);
 	}
@@ -2563,16 +2542,17 @@ mbc_free(Allctr_t *allctr, void *p, Carrier_t **busy_pcrr_pp)
     ASSERT(blk_sz % sizeof(Unit_t) == 0);
     ASSERT(IS_MBC_BLK(blk));
 
-    if (is_first_blk
-	&& is_last_blk
-	&& allctr->main_carrier != FIRST_BLK_TO_MBC(allctr, blk)) {
-	destroy_carrier(allctr, blk, busy_pcrr_pp);
+    if (is_first_blk && is_last_blk && crr != allctr->main_carrier) {
+        destroy_carrier(allctr, blk, busy_pcrr_pp);
     }
     else {
 	(*allctr->link_free_block)(allctr, blk);
 	HARD_CHECK_BLK_CARRIER(allctr, blk);
 #ifdef ERTS_SMP
-	check_abandon_carrier(allctr, blk, busy_pcrr_pp);
+        if (busy_pcrr_pp && *busy_pcrr_pp)
+            update_pooled_tree(allctr, crr, blk_sz);
+        else
+            check_abandon_carrier(allctr, blk, busy_pcrr_pp);
 #endif
     }
 }
@@ -2608,8 +2588,19 @@ mbc_realloc(Allctr_t *allctr, void *p, Uint size, Uint32 alcu_flgs,
 #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 */
+    if (busy_pcrr_pp && *busy_pcrr_pp) {
+        /*
+         * Don't want to use carrier in pool
+         */
+        new_p = mbc_alloc(allctr, size);
+        if (!new_p)
+            return NULL;
+        new_blk = UMEM2BLK(new_p);
+        ASSERT(!(IS_MBC_BLK(new_blk) && ABLK_TO_MBC(new_blk) == *busy_pcrr_pp));
+        sys_memcpy(new_p, p, MIN(size, old_blk_sz - ABLK_HDR_SZ));
+        mbc_free(allctr, p, busy_pcrr_pp);
+        return new_p;
+    }
 #endif
 
     get_blk_sz = blk_sz = UMEMSZ2BLKSZ(allctr, size);
@@ -2845,9 +2836,7 @@ 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);
@@ -2952,8 +2941,7 @@ mbc_realloc(Allctr_t *allctr, void *p, Uint size, Uint32 alcu_flgs,
 #ifdef ERTS_SMP
 
 #define ERTS_ALC_MAX_DEALLOC_CARRIER		10
-#define ERTS_ALC_CPOOL_MAX_FETCH_INSPECT	20
-#define ERTS_ALC_CPOOL_MAX_TRAITOR_INSPECT	10
+#define ERTS_ALC_CPOOL_MAX_FETCH_INSPECT	100
 #define ERTS_ALC_CPOOL_CHECK_LIMIT_COUNT	100
 #define ERTS_ALC_CPOOL_MAX_FAILED_STAT_READS	3
 
@@ -3117,19 +3105,18 @@ 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;
+    Allctr_t *orig_allctr = crr->cpool.orig_allctr;
 
     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_atomic_add_nob(&orig_allctr->cpool.stat.blocks_size,
 			(erts_aint_t) crr->cpool.blocks_size);
-    erts_atomic_add_nob(&allctr->cpool.stat.no_blocks,
+    erts_atomic_add_nob(&orig_allctr->cpool.stat.no_blocks,
 			(erts_aint_t) crr->cpool.blocks);
-    erts_atomic_add_nob(&allctr->cpool.stat.carriers_size,
+    erts_atomic_add_nob(&orig_allctr->cpool.stat.carriers_size,
 			(erts_aint_t) CARRIER_SZ(crr));
-    erts_atomic_inc_nob(&allctr->cpool.stat.no_carriers);
+    erts_atomic_inc_nob(&orig_allctr->cpool.stat.no_carriers);
 
     /*
      * We search in 'next' direction and begin by passing
@@ -3190,8 +3177,6 @@ cpool_insert(Allctr_t *allctr, Carrier_t *crr)
 			 (erts_aint_t) &crr->cpool,
 			 (erts_aint_t) cpd1p);
 
-    erts_smp_atomic_set_wb(&crr->allctr,
-			   ((erts_aint_t) allctr)|ERTS_CRR_ALCTR_FLG_IN_POOL);
     LTTNG3(carrier_pool_put, ERTS_ALC_A2AD(allctr->alloc_no), allctr->ix, CARRIER_SZ(crr));
 }
 
@@ -3293,130 +3278,126 @@ cpool_delete(Allctr_t *allctr, Allctr_t *prev_allctr, Carrier_t *crr)
 static Carrier_t *
 cpool_fetch(Allctr_t *allctr, UWord size)
 {
-    int i, i_stop, has_passed_sentinel;
+    enum { IGNORANT, HAS_SEEN_SENTINEL, THE_LAST_ONE } loop_state;
+    int i;
     Carrier_t *crr;
+    Carrier_t *reinsert_crr = NULL;
     ErtsAlcCPoolData_t *cpdp;
-    ErtsAlcCPoolData_t *cpool_entrance;
+    ErtsAlcCPoolData_t *cpool_entrance = NULL;
     ErtsAlcCPoolData_t *sentinel;
-    ErtsDoubleLink_t* dl;
-    ErtsDoubleLink_t* first_old_traitor;
 
     ERTS_ALC_CPOOL_ASSERT(allctr->alloc_no == ERTS_ALC_A_INVALID /* testcase */
 			  || erts_thr_progress_is_managed_thread());
 
     i = ERTS_ALC_CPOOL_MAX_FETCH_INSPECT;
-    first_old_traitor = allctr->cpool.traitor_list.next;
-    cpool_entrance = NULL;
 
     LTTNG3(carrier_pool_get, ERTS_ALC_A2AD(allctr->alloc_no), allctr->ix, (unsigned long)size);
     /*
-     * Search my own pooled_list,
+     * Search my own pooled_tree,
      * i.e my abandoned carriers that were in the pool last time I checked.
      */
+    do {
+        erts_aint_t exp, act;
+
+        crr = aoff_lookup_pooled_mbc(allctr, size);
+        if (!crr)
+            break;
+
+        ASSERT(crr->cpool.state == ERTS_MBC_WAS_POOLED);
+        ASSERT(crr->cpool.orig_allctr == allctr);
+
+        aoff_remove_pooled_mbc(allctr, crr);
+
+        exp = erts_smp_atomic_read_nob(&crr->allctr);
+        if (exp & ERTS_CRR_ALCTR_FLG_IN_POOL) {
+            ASSERT((exp & ~ERTS_CRR_ALCTR_FLG_MASK) == (erts_aint_t)allctr);
+            if (erts_atomic_read_nob(&crr->cpool.max_size) < size) {
+                /*
+                 * This carrier has been fetched and inserted back again
+                 * by a foreign allocator. That's why it has a stale search size.
+                 */
+                ASSERT(exp & ERTS_CRR_ALCTR_FLG_HOMECOMING);
+                crr->cpool.pooled.hdr.bhdr = erts_atomic_read_nob(&crr->cpool.max_size);
+                aoff_add_pooled_mbc(allctr, crr);
+                INC_CC(allctr->cpool.stat.skip_size);
+                continue;
+            }
+            else if (exp & ERTS_CRR_ALCTR_FLG_BUSY) {
+                /*
+                 * This must be our own carrier as part of a realloc call.
+                 * Skip it to make things simpler.
+                 * Must wait to re-insert to not be found again by lookup.
+                 */
+                ASSERT(!reinsert_crr);
+                reinsert_crr = crr;
+                INC_CC(allctr->cpool.stat.skip_busy);
+                continue;
+            }
 
-    dl = allctr->cpool.pooled_list.next;
-    while(dl != &allctr->cpool.pooled_list) {
-	erts_aint_t exp, act;
-	crr = (Carrier_t *) (((char *) dl) - offsetof(Carrier_t, cpool.abandoned));
-
-	ASSERT(!is_in_list(&allctr->cpool.traitor_list, dl));
-	ASSERT(crr->cpool.orig_allctr == allctr);
-	dl = dl->next;
-	exp = erts_smp_atomic_read_rb(&crr->allctr);
-	if ((exp & ERTS_CRR_ALCTR_FLG_MASK) == ERTS_CRR_ALCTR_FLG_IN_POOL
-	    && erts_atomic_read_nob(&crr->cpool.max_size) >= size) {
-	    /* 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 & ~ERTS_CRR_ALCTR_FLG_MASK)), crr);
-		unlink_abandoned_carrier(crr);
-
-		/* Move sentinel to continue next search from here */
-		relink_edl_before(dl, &allctr->cpool.pooled_list);
-		return crr;
-	    }
-	    exp = act;
-	}
-	if (exp & ERTS_CRR_ALCTR_FLG_IN_POOL) {
-	    if (!cpool_entrance)
-		cpool_entrance = &crr->cpool;
-	}
-	else { /* Not in pool, move to traitor_list */
-	    unlink_abandoned_carrier(crr);
-	    link_abandoned_carrier(&allctr->cpool.traitor_list, crr);
-	}
-	if (--i <= 0) {
-	    /* Move sentinel to continue next search from here */
-	    relink_edl_before(dl, &allctr->cpool.pooled_list);
-	    return NULL;
-	}
-    }
+            /* Try to fetch it... */
+            act = erts_smp_atomic_cmpxchg_mb(&crr->allctr,
+                                             exp & ~ERTS_CRR_ALCTR_FLG_IN_POOL,
+                                             exp);
+            if (act == exp) {
+                cpool_delete(allctr, allctr, crr);
+                crr->cpool.state = ERTS_MBC_IS_HOME;
+
+                if (reinsert_crr)
+                    aoff_add_pooled_mbc(allctr, reinsert_crr);
+                return crr;
+            }
+            exp = act;
+            INC_CC(allctr->cpool.stat.skip_race);
+        }
+        else
+            INC_CC(allctr->cpool.stat.skip_not_pooled);
 
-    /* Now search traitor_list.
-     * i.e carriers employed by other allocators last time I checked.
-     * They might have been abandoned since then.
-     */
+        /* Not in pool anymore */
+        ASSERT(!(exp & ERTS_CRR_ALCTR_FLG_BUSY));
+        crr->cpool.state = ERTS_MBC_WAS_TRAITOR;
 
-    i_stop = (i < ERTS_ALC_CPOOL_MAX_TRAITOR_INSPECT ?
-	      0 : i - ERTS_ALC_CPOOL_MAX_TRAITOR_INSPECT);
-    dl = first_old_traitor;
-    while(dl != &allctr->cpool.traitor_list) {
-	erts_aint_t exp, act;
-	crr = (Carrier_t *) (((char *) dl) - offsetof(Carrier_t, cpool.abandoned));
-	ASSERT(dl != &allctr->cpool.pooled_list);
-	ASSERT(crr->cpool.orig_allctr == allctr);
-	dl = dl->next;
-	exp = erts_smp_atomic_read_rb(&crr->allctr);
-	if (exp & ERTS_CRR_ALCTR_FLG_IN_POOL) {
-	    if (!(exp & ERTS_CRR_ALCTR_FLG_BUSY)
-		&& erts_atomic_read_nob(&crr->cpool.max_size) >= size) {
-		/* 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 & ~ERTS_CRR_ALCTR_FLG_MASK)), crr);
-		    unlink_abandoned_carrier(crr);
+    }while (--i > 0);
 
-		    /* Move sentinel to continue next search from here */
-		    relink_edl_before(dl, &allctr->cpool.traitor_list);
-		    return crr;
-		}
-		exp = act;
-	    }
-	    if (exp & ERTS_CRR_ALCTR_FLG_IN_POOL) {
-		if (!cpool_entrance)
-		    cpool_entrance = &crr->cpool;
+    if (reinsert_crr)
+        aoff_add_pooled_mbc(allctr, reinsert_crr);
 
-		/* Move to pooled_list */
-		unlink_abandoned_carrier(crr);
-		link_abandoned_carrier(&allctr->cpool.pooled_list, crr);
-	    }
-	}
-	if (--i <= i_stop) {
-	    /* Move sentinel to continue next search from here */
-	    relink_edl_before(dl, &allctr->cpool.traitor_list);
-	    if (i > 0)
-		break;
-	    else
-		return NULL;
-	}
+    /*
+     * Try find a nice cpool_entrance
+     */
+    while (allctr->cpool.pooled_tree) {
+        erts_aint_t iallctr;
+
+        crr = ErtsContainerStruct(allctr->cpool.pooled_tree, Carrier_t, cpool.pooled);
+        iallctr = erts_smp_atomic_read_nob(&crr->allctr);
+        if (iallctr & ERTS_CRR_ALCTR_FLG_IN_POOL) {
+            cpool_entrance = &crr->cpool;
+            break;
+        }
+        /* Not in pool anymore */
+        ASSERT(!(iallctr & ERTS_CRR_ALCTR_FLG_BUSY));
+        aoff_remove_pooled_mbc(allctr, crr);
+        crr->cpool.state = ERTS_MBC_WAS_TRAITOR;
+
+        if (--i <= 0) {
+            INC_CC(allctr->cpool.stat.fail_pooled);
+            return NULL;
+        }
     }
 
+
     /*
      * Finally search the shared pool and try employ foreign carriers
      */
-
     sentinel = &carrier_pool[allctr->alloc_no].sentinel;
     if (cpool_entrance) {
-	/* We saw a pooled carried above, use it as entrance into the pool
+        /*
+         * We saw a pooled carried above, use it as entrance into the pool
 	 */
 	cpdp = cpool_entrance;
     }
     else {
-	/* No pooled carried seen above. Start search at cpool sentinel,
+        /*
+         * No pooled carried seen above. Start search at cpool sentinel,
 	 * but begin by passing one element before trying to fetch.
 	 * This in order to avoid contention with threads inserting elements.
 	 */
@@ -3426,8 +3407,8 @@ cpool_fetch(Allctr_t *allctr, UWord size)
 	    goto check_dc_list;
     }
 
-    has_passed_sentinel = 0;
-    while (1) {
+    loop_state = IGNORANT;
+    do {
 	erts_aint_t exp;
 	cpdp = cpool_aint2cpd(cpool_read(&cpdp->prev));
 	if (cpdp == cpool_entrance) {
@@ -3436,38 +3417,52 @@ cpool_fetch(Allctr_t *allctr, UWord size)
 		if (cpdp == sentinel)
 		    break;
 	    }
-	    i = 0; /* Last one to inspect */
+            loop_state = THE_LAST_ONE;
 	}
 	else if (cpdp == sentinel) {
-	    if (has_passed_sentinel) {
+	    if (loop_state == HAS_SEEN_SENTINEL) {
 		/* We been here before. cpool_entrance must have been removed */
+                INC_CC(allctr->cpool.stat.entrance_removed);
 		break;
 	    }
 	    cpdp = cpool_aint2cpd(cpool_read(&cpdp->prev));
 	    if (cpdp == sentinel)
                 break;
-	    has_passed_sentinel = 1;
+            loop_state = HAS_SEEN_SENTINEL;
 	}
-	crr = (Carrier_t *)(((char *)cpdp) - offsetof(Carrier_t, cpool));
+	crr = ErtsContainerStruct(cpdp, Carrier_t, cpool);
 	exp = erts_smp_atomic_read_rb(&crr->allctr);
-	if (((exp & (ERTS_CRR_ALCTR_FLG_MASK)) == ERTS_CRR_ALCTR_FLG_IN_POOL)
-	    && (erts_atomic_read_nob(&cpdp->max_size) >= size)) {
+
+        if (erts_atomic_read_nob(&cpdp->max_size) < size) {
+            INC_CC(allctr->cpool.stat.skip_size);
+        }
+        else if ((exp & (ERTS_CRR_ALCTR_FLG_IN_POOL | ERTS_CRR_ALCTR_FLG_BUSY))
+                  == ERTS_CRR_ALCTR_FLG_IN_POOL) {
 	    erts_aint_t act;
-	    /* Try to fetch it... */
-	    act = erts_smp_atomic_cmpxchg_mb(&crr->allctr,
-					     (erts_aint_t) allctr,
-					     exp);
+            erts_aint_t want = (((erts_aint_t) allctr)
+                                | (exp & ERTS_CRR_ALCTR_FLG_HOMECOMING));
+            /* Try to fetch it... */
+	    act = erts_smp_atomic_cmpxchg_mb(&crr->allctr, want, exp);
 	    if (act == exp) {
 		cpool_delete(allctr, ((Allctr_t *) (act & ~ERTS_CRR_ALCTR_FLG_MASK)), crr);
 		if (crr->cpool.orig_allctr == allctr) {
 		    unlink_abandoned_carrier(crr);
-		}
+                    crr->cpool.state = ERTS_MBC_IS_HOME;
+                }
 		return crr;
 	    }
 	}
-	if (--i <= 0)
+
+        if (exp & ERTS_CRR_ALCTR_FLG_BUSY)
+            INC_CC(allctr->cpool.stat.skip_busy);
+        else
+            INC_CC(allctr->cpool.stat.skip_race);
+
+	if (--i <= 0) {
+            INC_CC(allctr->cpool.stat.fail_shared);
 	    return NULL;
-    }
+        }
+    }while (loop_state != THE_LAST_ONE);
 
 check_dc_list:
     /* Last; check our own pending dealloc carrier list... */
@@ -3476,23 +3471,23 @@ check_dc_list:
 	if (erts_atomic_read_nob(&crr->cpool.max_size) >= size) {
 	    Block_t* blk;
 	    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) & ~ERTS_CRR_ALCTR_FLG_MASK));
-#else
-	    erts_smp_atomic_set_nob(&crr->allctr, ((erts_aint_t) allctr));
-#endif
+	    ERTS_ALC_CPOOL_ASSERT(erts_smp_atomic_read_nob(&crr->allctr)
+                                  == ((erts_aint_t) allctr));
 	    blk = MBC_TO_FIRST_BLK(allctr, crr);
 	    ASSERT(FBLK_TO_MBC(blk) == crr);
 	    allctr->link_free_block(allctr, blk);
 	    return crr;
 	}
 	crr = crr->prev;
-	if (--i <= 0)
+	if (--i <= 0) {
+            INC_CC(allctr->cpool.stat.fail_pend_dealloc);
 	    return NULL;
+        }
     }
 
+    if (i != ERTS_ALC_CPOOL_MAX_FETCH_INSPECT)
+        INC_CC(allctr->cpool.stat.fail);
+
     return NULL;
 }
 
@@ -3547,9 +3542,6 @@ static void
 schedule_dealloc_carrier(Allctr_t *allctr, Carrier_t *crr)
 {
     Allctr_t *orig_allctr;
-    Block_t *blk;
-    int check_pending_dealloc;
-    erts_aint_t max_size;
 
     ASSERT(IS_MB_CARRIER(crr));
 
@@ -3560,9 +3552,17 @@ schedule_dealloc_carrier(Allctr_t *allctr, Carrier_t *crr)
 
     orig_allctr = crr->cpool.orig_allctr;
 
-    if (allctr != orig_allctr) {
-	int cinit = orig_allctr->dd.ix - allctr->dd.ix;
-
+    if (allctr == orig_allctr) {
+        if (!(erts_smp_atomic_read_nob(&crr->allctr) & ERTS_CRR_ALCTR_FLG_HOMECOMING)) {
+            dealloc_my_carrier(allctr, crr);
+        }
+        /*else
+         * Carrier was abandoned earlier by other thread and
+         * is still waiting for us in dd-queue.
+         * handle_delayed_dealloc() will handle it when crr is dequeued.
+         */
+    }
+    else {
 	/*
 	 * We send the carrier to its origin for deallocation.
 	 * This in order:
@@ -3571,29 +3571,39 @@ schedule_dealloc_carrier(Allctr_t *allctr, Carrier_t *crr)
 	 * - to ensure that we always only reuse empty carriers
 	 *   originating from our own thread specific mseg_alloc
 	 *   instance which is beneficial on NUMA systems.
-	 *
-	 * The receiver will recognize that this is a carrier to
-	 * deallocate (and not a block which is the common case)
-	 * since the block is an mbc block that is free and last
-	 * in the carrier.
 	 */
-	blk = MBC_TO_FIRST_BLK(allctr, crr);
-	ERTS_ALC_CPOOL_ASSERT(IS_FREE_LAST_MBC_BLK(blk));
+        erts_aint_t iallctr;
+#ifdef ERTS_ALC_CPOOL_DEBUG
+	Block_t* first_blk = MBC_TO_FIRST_BLK(allctr, crr);
+	ERTS_ALC_CPOOL_ASSERT(IS_FREE_LAST_MBC_BLK(first_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(allctr, blk));
-	ERTS_ALC_CPOOL_ASSERT(((erts_aint_t) allctr)
-			      == (erts_smp_atomic_read_nob(&crr->allctr)
-				  & ~ERTS_CRR_ALCTR_FLG_MASK));
+	ERTS_ALC_CPOOL_ASSERT(IS_MBC_FIRST_ABLK(allctr, first_blk));
+	ERTS_ALC_CPOOL_ASSERT(crr == FBLK_TO_MBC(first_blk));
+	ERTS_ALC_CPOOL_ASSERT(crr == FIRST_BLK_TO_MBC(allctr, first_blk));
+	ERTS_ALC_CPOOL_ASSERT((erts_smp_atomic_read_nob(&crr->allctr)
+                               & ~ERTS_CRR_ALCTR_FLG_HOMECOMING)
+                              == (erts_aint_t) allctr);
+#endif
 
-	if (ddq_enqueue(&orig_allctr->dd.q, BLK2UMEM(blk), cinit))
-	    erts_alloc_notify_delayed_dealloc(orig_allctr->ix);
-	return;
+        iallctr = (erts_aint_t)orig_allctr | ERTS_CRR_ALCTR_FLG_HOMECOMING;
+        if (!(erts_smp_atomic_xchg_nob(&crr->allctr, iallctr)
+              & ERTS_CRR_ALCTR_FLG_HOMECOMING)) {
+            enqueue_homecoming(allctr, crr);
+        }
     }
+}
+
+static void dealloc_my_carrier(Allctr_t *allctr, Carrier_t *crr)
+{
+    Block_t *blk;
+    int check_pending_dealloc;
+    erts_aint_t max_size;
 
-    if (is_abandoned(crr))
-	unlink_abandoned_carrier(crr);
+    ERTS_ALC_CPOOL_ASSERT(allctr == crr->cpool.orig_allctr);
+    if (is_abandoned(crr)) {
+        unlink_abandoned_carrier(crr);
+        crr->cpool.state = ERTS_MBC_IS_HOME;
+    }
 
     if (crr->cpool.thr_prgr == ERTS_THR_PRGR_INVALID
 	|| erts_thr_progress_has_reached(crr->cpool.thr_prgr)) {
@@ -3625,6 +3635,7 @@ schedule_dealloc_carrier(Allctr_t *allctr, Carrier_t *crr)
 static ERTS_INLINE void
 cpool_init_carrier_data(Allctr_t *allctr, Carrier_t *crr)
 {
+    crr->cpool.homecoming_dd.blk.bhdr = HOMECOMING_MBC_BLK_HDR;
     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;
@@ -3643,8 +3654,7 @@ cpool_init_carrier_data(Allctr_t *allctr, Carrier_t *crr)
 	    limit = (csz/100)*allctr->cpool.util_limit;
 	crr->cpool.abandon_limit = limit;
     }
-    crr->cpool.abandoned.next = NULL;
-    crr->cpool.abandoned.prev = NULL;
+    crr->cpool.state = ERTS_MBC_IS_HOME;
 }
 
 static void
@@ -3670,23 +3680,62 @@ set_new_allctr_abandon_limit(Allctr_t *allctr)
 static void
 abandon_carrier(Allctr_t *allctr, Carrier_t *crr)
 {
-    erts_aint_t max_size;
+    erts_aint_t iallctr;
 
-    STAT_MBC_CPOOL_INSERT(allctr, crr);
+    STAT_MBC_ABANDON(allctr, crr);
 
     unlink_carrier(&allctr->mbc_list, crr);
-    if (crr->cpool.orig_allctr == allctr) {
-	link_abandoned_carrier(&allctr->cpool.pooled_list, crr);
+    allctr->remove_mbc(allctr, crr);
+    set_new_allctr_abandon_limit(allctr);
+
+    cpool_insert(allctr, crr);
+
+
+    iallctr = erts_smp_atomic_read_nob(&crr->allctr);
+    if (allctr == crr->cpool.orig_allctr) {
+        /* preserve HOMECOMING flag */
+        ASSERT((iallctr & ~ERTS_CRR_ALCTR_FLG_HOMECOMING) == (erts_aint_t)allctr);
+        erts_smp_atomic_set_wb(&crr->allctr, iallctr | ERTS_CRR_ALCTR_FLG_IN_POOL);
+        poolify_my_carrier(allctr, crr);
     }
+    else {
+        ASSERT((iallctr & ~ERTS_CRR_ALCTR_FLG_HOMECOMING) == (erts_aint_t)allctr);
+        iallctr = ((erts_aint_t)crr->cpool.orig_allctr |
+                   ERTS_CRR_ALCTR_FLG_HOMECOMING |
+                   ERTS_CRR_ALCTR_FLG_IN_POOL);
+        if (!(erts_smp_atomic_xchg_wb(&crr->allctr, iallctr)
+              & ERTS_CRR_ALCTR_FLG_HOMECOMING)) {
+
+            enqueue_homecoming(allctr, crr);
+        }
+    }
+}
 
-    allctr->remove_mbc(allctr, crr);
+static void
+enqueue_homecoming(Allctr_t* allctr, Carrier_t* crr)
+{
+    Allctr_t* orig_allctr = crr->cpool.orig_allctr;
+    const int cinit = orig_allctr->dd.ix - allctr->dd.ix;
+    Block_t* dd_blk = &crr->cpool.homecoming_dd.blk;
 
-    max_size = (erts_aint_t) allctr->largest_fblk_in_mbc(allctr, crr);
-    erts_atomic_set_nob(&crr->cpool.max_size, max_size);
+    /*
+     * The receiver will recognize this as a carrier
+     * (and not a block which is the common case)
+     * since the block header is HOMECOMING_MBC_BLK_HDR.
+     */
+    ASSERT(dd_blk->bhdr == HOMECOMING_MBC_BLK_HDR);
+    if (ddq_enqueue(&orig_allctr->dd.q, BLK2UMEM(dd_blk), cinit))
+        erts_alloc_notify_delayed_dealloc(orig_allctr->ix);
+}
 
-    cpool_insert(allctr, crr);
+static void
+poolify_my_carrier(Allctr_t *allctr, Carrier_t *crr)
+{
+    ERTS_ALC_CPOOL_ASSERT(allctr == crr->cpool.orig_allctr);
 
-    set_new_allctr_abandon_limit(allctr);
+    crr->cpool.pooled.hdr.bhdr = erts_atomic_read_nob(&crr->cpool.max_size);
+    aoff_add_pooled_mbc(allctr, crr);
+    crr->cpool.state = ERTS_MBC_WAS_POOLED;
 }
 
 static void
@@ -3845,6 +3894,7 @@ create_carrier(Allctr_t *allctr, Uint umem_sz, UWord flags)
 	crr = cpool_fetch(allctr, blk_sz);
 	if (crr) {
 	    STAT_MBC_CPOOL_FETCH(allctr, crr);
+            INC_CC(allctr->cpool.stat.fetch);
 	    link_carrier(&allctr->mbc_list, crr);
 	    (*allctr->add_mbc)(allctr, crr);
 	    blk = (*allctr->get_free_block)(allctr, blk_sz, NULL, 0);
@@ -4206,16 +4256,21 @@ destroy_carrier(Allctr_t *allctr, Block_t *blk, Carrier_t **busy_pcrr_pp)
 
 #ifdef ERTS_SMP
 	if (busy_pcrr_pp && *busy_pcrr_pp) {
+            erts_aint_t iallctr = erts_smp_atomic_read_nob(&crr->allctr);
 	    ERTS_ALC_CPOOL_ASSERT(*busy_pcrr_pp == crr);
-	    *busy_pcrr_pp = NULL;
-	    ERTS_ALC_CPOOL_ASSERT(erts_smp_atomic_read_nob(&crr->allctr)
-				  == (((erts_aint_t) allctr)
-				      | ERTS_CRR_ALCTR_FLG_IN_POOL
-				      | ERTS_CRR_ALCTR_FLG_BUSY));
-	    erts_smp_atomic_set_nob(&crr->allctr, ((erts_aint_t) allctr));
+            ERTS_ALC_CPOOL_ASSERT((iallctr & ~ERTS_CRR_ALCTR_FLG_HOMECOMING)
+                                  == (((erts_aint_t) allctr)
+                                      | ERTS_CRR_ALCTR_FLG_IN_POOL
+                                      | ERTS_CRR_ALCTR_FLG_BUSY));
+            ERTS_ALC_CPOOL_ASSERT(allctr == crr->cpool.orig_allctr);
+
+            *busy_pcrr_pp = NULL;
+	    erts_smp_atomic_set_nob(&crr->allctr,
+                                    (iallctr & ~(ERTS_CRR_ALCTR_FLG_IN_POOL |
+                                                 ERTS_CRR_ALCTR_FLG_BUSY)));
 	    cpool_delete(allctr, allctr, crr);
 	}
-	else
+        else
 #endif
 	{
 	    unlink_carrier(&allctr->mbc_list, crr);
@@ -4267,7 +4322,6 @@ static struct {
     Eterm e;
     Eterm t;
     Eterm ramv;
-    Eterm sbct;
 #if HAVE_ERTS_MSEG
     Eterm asbcst;
     Eterm rsbcst;
@@ -4284,6 +4338,8 @@ static struct {
     Eterm smbcs;
     Eterm mbcgs;
     Eterm acul;
+    Eterm acnl;
+    Eterm acfml;
 
 #if HAVE_ERTS_MSEG
     Eterm mmc;
@@ -4296,6 +4352,17 @@ static struct {
     Eterm mbcs;
 #ifdef ERTS_SMP
     Eterm mbcs_pool;
+    Eterm fetch;
+    Eterm fail_pooled;
+    Eterm fail_shared;
+    Eterm fail_pend_dealloc;
+    Eterm fail;
+    Eterm skip_size;
+    Eterm skip_busy;
+    Eterm skip_not_pooled;
+    Eterm skip_homecoming;
+    Eterm skip_race;
+    Eterm entrance_removed;
 #endif
     Eterm sbcs;
 
@@ -4357,7 +4424,6 @@ init_atoms(Allctr_t *allctr)
 	AM_INIT(e);
 	AM_INIT(t);
 	AM_INIT(ramv);
-	AM_INIT(sbct);
 #if HAVE_ERTS_MSEG
 	AM_INIT(asbcst);
 	AM_INIT(rsbcst);
@@ -4374,6 +4440,8 @@ init_atoms(Allctr_t *allctr)
 	AM_INIT(smbcs);
 	AM_INIT(mbcgs);
 	AM_INIT(acul);
+        AM_INIT(acnl);
+        AM_INIT(acfml);
 
 #if HAVE_ERTS_MSEG
 	AM_INIT(mmc);
@@ -4386,6 +4454,17 @@ init_atoms(Allctr_t *allctr)
 	AM_INIT(mbcs);
 #ifdef ERTS_SMP
 	AM_INIT(mbcs_pool);
+	AM_INIT(fetch);
+        AM_INIT(fail_pooled);
+        AM_INIT(fail_shared);
+        AM_INIT(fail_pend_dealloc);
+        AM_INIT(fail);
+        AM_INIT(skip_size);
+        AM_INIT(skip_busy);
+        AM_INIT(skip_not_pooled);
+        AM_INIT(skip_homecoming);
+        AM_INIT(skip_race);
+        AM_INIT(entrance_removed);
 #endif
 	AM_INIT(sbcs);
 
@@ -4671,9 +4750,56 @@ info_cpool(Allctr_t *allctr,
 
     if (hpp || szp) {
 	res = NIL;
+
+      if (!sz_only) {
+        add_3tup(hpp, szp, &res, am.fail_pooled,
+                 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_GIGA_VAL(allctr->cpool.stat.fail_pooled)),
+                 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_VAL(allctr->cpool.stat.fail_pooled)));
+
+        add_3tup(hpp, szp, &res, am.fail_shared,
+                 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_GIGA_VAL(allctr->cpool.stat.fail_shared)),
+                 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_VAL(allctr->cpool.stat.fail_shared)));
+
+        add_3tup(hpp, szp, &res, am.fail_pend_dealloc,
+                 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_GIGA_VAL(allctr->cpool.stat.fail_pend_dealloc)),
+                 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_VAL(allctr->cpool.stat.fail_pend_dealloc)));
+
+        add_3tup(hpp, szp, &res, am.fail,
+                 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_GIGA_VAL(allctr->cpool.stat.fail)),
+                 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_VAL(allctr->cpool.stat.fail)));
+
+        add_3tup(hpp, szp, &res, am.fetch,
+                 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_GIGA_VAL(allctr->cpool.stat.fetch)),
+                 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_VAL(allctr->cpool.stat.fetch)));
+
+        add_3tup(hpp, szp, &res, am.skip_size,
+                 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_GIGA_VAL(allctr->cpool.stat.skip_size)),
+                 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_VAL(allctr->cpool.stat.skip_size)));
+
+        add_3tup(hpp, szp, &res, am.skip_busy,
+                 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_GIGA_VAL(allctr->cpool.stat.skip_busy)),
+                 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_VAL(allctr->cpool.stat.skip_busy)));
+
+        add_3tup(hpp, szp, &res, am.skip_not_pooled,
+                 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_GIGA_VAL(allctr->cpool.stat.skip_not_pooled)),
+                 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_VAL(allctr->cpool.stat.skip_not_pooled)));
+
+        add_3tup(hpp, szp, &res, am.skip_homecoming,
+                 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_GIGA_VAL(allctr->cpool.stat.skip_homecoming)),
+                 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_VAL(allctr->cpool.stat.skip_homecoming)));
+
+        add_3tup(hpp, szp, &res, am.skip_race,
+                 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_GIGA_VAL(allctr->cpool.stat.skip_race)),
+                 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_VAL(allctr->cpool.stat.skip_race)));
+
+        add_3tup(hpp, szp, &res, am.entrance_removed,
+                 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_GIGA_VAL(allctr->cpool.stat.entrance_removed)),
+                 bld_unstable_uint(hpp, szp, ERTS_ALC_CC_VAL(allctr->cpool.stat.entrance_removed)));
+
 	add_2tup(hpp, szp, &res,
 		 am.carriers_size,
 		 bld_unstable_uint(hpp, szp, csz));
+      }
 	if (!sz_only)
 	    add_2tup(hpp, szp, &res,
 		     am.carriers,
@@ -4933,7 +5059,7 @@ info_options(Allctr_t *allctr,
 	     Uint *szp)
 {
     Eterm res = THE_NON_VALUE;
-    int acul;
+    UWord acul, acnl, acfml;
 
     if (!allctr) {
 	if (print_to_p)
@@ -4947,8 +5073,10 @@ info_options(Allctr_t *allctr,
 
 #ifdef ERTS_SMP
     acul = allctr->cpool.util_limit;
+    acnl = allctr->cpool.in_pool_limit;
+    acfml = allctr->cpool.fblk_min_limit;
 #else
-    acul = 0;
+    acul = 0; acnl = 0; acfml = 0;
 #endif
 
     if (print_to_p) {
@@ -4977,7 +5105,7 @@ info_options(Allctr_t *allctr,
 		   "option lmbcs: %beu\n"
 		   "option smbcs: %beu\n"
 		   "option mbcgs: %beu\n"
-		   "option acul: %d\n",
+		   "option acul: %bpu\n",
 		   topt,
 		   allctr->ramv ? "true" : "false",
 		   allctr->sbc_threshold,
@@ -5002,9 +5130,15 @@ info_options(Allctr_t *allctr,
 				  hpp, szp);
 
     if (hpp || szp) {
+        add_2tup(hpp, szp, &res,
+                 am.acfml,
+                 bld_uint(hpp, szp, acfml));
+        add_2tup(hpp, szp, &res,
+                 am.acnl,
+                 bld_uint(hpp, szp, acnl));
 	add_2tup(hpp, szp, &res,
 		 am.acul,
-		 bld_uint(hpp, szp, (UWord) acul));
+		 bld_uint(hpp, szp, acul));
 	add_2tup(hpp, szp, &res,
 		 am.mbcgs,
 		 bld_uint(hpp, szp, allctr->mbc_growth_stages));
@@ -5040,7 +5174,7 @@ info_options(Allctr_t *allctr,
 		 bld_uint(hpp, szp, allctr->mseg_opt.abs_shrink_th));
 #endif
 	add_2tup(hpp, szp, &res,
-		 am.sbct,
+		 am_sbct,
 		 bld_uint(hpp, szp, allctr->sbc_threshold));
 	add_2tup(hpp, szp, &res, am.ramv, allctr->ramv ? am_true : am_false);
 	add_2tup(hpp, szp, &res, am.t, (allctr->t ? am_true : am_false));
@@ -5618,12 +5752,13 @@ erts_alcu_free_thr_pref(ErtsAlcType_t type, void *extra, void *p)
 	pref_allctr = get_pref_allctr(extra);
 	used_allctr = get_used_allctr(pref_allctr, ERTS_ALC_TS_PREF_LOCK_IF_USED,
 				      p, NULL, &busy_pcrr_p);
-	if (pref_allctr != used_allctr)
+	if (pref_allctr != used_allctr) {
 	    enqueue_dealloc_other_instance(type,
-					   used_allctr,
-					   p,
-					   (used_allctr->dd.ix
-					    - pref_allctr->dd.ix));
+                                           used_allctr,
+                                           p,
+                                           (used_allctr->dd.ix
+                                            - pref_allctr->dd.ix));
+        }
 	else {
 	    ERTS_ALCU_DBG_CHK_THR_ACCESS(used_allctr);
 	    do_erts_alcu_free(type, used_allctr, p, &busy_pcrr_p);
@@ -6003,6 +6138,37 @@ erts_alcu_realloc_mv_thr_pref(ErtsAlcType_t type, void *extra,
 
 #endif
 
+static Uint adjust_sbct(Allctr_t* allctr, Uint sbct)
+{
+#ifndef ARCH_64
+    if (sbct > 0) {
+	Uint max_mbc_block_sz = UNIT_CEILING(sbct - 1 + ABLK_HDR_SZ);
+	if (max_mbc_block_sz + UNIT_FLOOR(allctr->min_block_size - 1) > MBC_ABLK_SZ_MASK
+	    || max_mbc_block_sz < sbct) { /* wrap around */
+	    /*
+	     * By limiting sbc_threshold to (hard limit - min_block_size)
+	     * we avoid having to split off free "residue blocks"
+	     * smaller than min_block_size.
+	     */
+	    max_mbc_block_sz = MBC_ABLK_SZ_MASK - UNIT_FLOOR(allctr->min_block_size - 1);
+	    sbct = max_mbc_block_sz - ABLK_HDR_SZ + 1;
+	}
+    }
+#endif
+    return sbct;
+}
+
+int erts_alcu_try_set_dyn_param(Allctr_t* allctr, Eterm param, Uint value)
+{
+    const Uint MIN_DYN_SBCT = 4000;  /* a lame catastrophe prevention */
+
+    if (param == am_sbct && value >= MIN_DYN_SBCT) {
+        allctr->sbc_threshold = adjust_sbct(allctr, value);
+        return 1;
+    }
+    return 0;
+}
+
 /* ------------------------------------------------------------------------- */
 
 int
@@ -6093,10 +6259,7 @@ erts_alcu_start(Allctr_t *allctr, AllctrInit_t *init)
 	    allctr->min_block_size = sz;
     }
 
-    allctr->cpool.pooled_list.next  = &allctr->cpool.pooled_list;
-    allctr->cpool.pooled_list.prev  = &allctr->cpool.pooled_list;
-    allctr->cpool.traitor_list.next = &allctr->cpool.traitor_list;
-    allctr->cpool.traitor_list.prev = &allctr->cpool.traitor_list;
+    allctr->cpool.pooled_tree = NULL;
     allctr->cpool.dc_list.first = NULL;
     allctr->cpool.dc_list.last = NULL;
     allctr->cpool.abandon_limit = 0;
@@ -6106,26 +6269,20 @@ erts_alcu_start(Allctr_t *allctr, AllctrInit_t *init)
     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->ts ? 0 : init->acul;
-#endif
-
-    allctr->sbc_threshold		= init->sbct;
-#ifndef ARCH_64
-    if (allctr->sbc_threshold > 0) {
-	Uint max_mbc_block_sz = UNIT_CEILING(allctr->sbc_threshold - 1 + ABLK_HDR_SZ); 
-	if (max_mbc_block_sz + UNIT_FLOOR(allctr->min_block_size - 1) > MBC_ABLK_SZ_MASK
-	    || max_mbc_block_sz < allctr->sbc_threshold) { /* wrap around */
-	    /* 
-	     * By limiting sbc_threshold to (hard limit - min_block_size)
-	     * we avoid having to split off free "residue blocks"
-	     * smaller than min_block_size.
-	     */
-	    max_mbc_block_sz = MBC_ABLK_SZ_MASK - UNIT_FLOOR(allctr->min_block_size - 1);
-	    allctr->sbc_threshold = max_mbc_block_sz - ABLK_HDR_SZ + 1;
-	}
+    if (!init->ts && init->acul && init->acnl) {
+        allctr->cpool.util_limit = init->acul;
+        allctr->cpool.in_pool_limit = init->acnl;
+        allctr->cpool.fblk_min_limit = init->acfml;
+    }
+    else {
+        allctr->cpool.util_limit = 0;
+        allctr->cpool.in_pool_limit = 0;
+        allctr->cpool.fblk_min_limit = 0;
     }
 #endif
 
+    allctr->sbc_threshold = adjust_sbct(allctr, init->sbct);
+
 #if HAVE_ERTS_MSEG
     if (allctr->mseg_opt.abs_shrink_th > ~((UWord) 0) / 100)
 	allctr->mseg_opt.abs_shrink_th = ~((UWord) 0) / 100;
@@ -6179,6 +6336,9 @@ erts_alcu_start(Allctr_t *allctr, AllctrInit_t *init)
         allctr->sys_realloc = &erts_alcu_sys_realloc;
         allctr->sys_dealloc = &erts_alcu_sys_dealloc;
     }
+
+    allctr->try_set_dyn_param = &erts_alcu_try_set_dyn_param;
+
 #if HAVE_ERTS_MSEG
     if (init->mseg_alloc) {
         ASSERT(init->mseg_realloc && init->mseg_dealloc);
@@ -6193,6 +6353,7 @@ erts_alcu_start(Allctr_t *allctr, AllctrInit_t *init)
         allctr->mseg_realloc = &erts_alcu_mseg_realloc;
         allctr->mseg_dealloc = &erts_alcu_mseg_dealloc;
     }
+
     /* If a custom carrier alloc function is specified, make sure it's used */
     if (init->mseg_alloc && !init->sys_alloc) {
         allctr->crr_set_flgs = CFLG_FORCE_MSEG;
diff --git a/erts/emulator/beam/erl_alloc_util.h b/erts/emulator/beam/erl_alloc_util.h
index aa13cda9fb..1c07086040 100644
--- a/erts/emulator/beam/erl_alloc_util.h
+++ b/erts/emulator/beam/erl_alloc_util.h
@@ -63,7 +63,9 @@ typedef struct {
     UWord lmbcs;
     UWord smbcs;
     UWord mbcgs;
-    int acul;
+    UWord acul;
+    UWord acnl;
+    UWord acfml;
 
     void *fix;
     size_t *fix_type_size;
@@ -118,6 +120,8 @@ typedef struct {
     1024*1024,		/* (bytes)  smbcs:  smallest mbc size            */\
     10,			/* (amount) mbcgs:  mbc growth stages            */\
     0,			/* (%)      acul:  abandon carrier utilization limit */\
+    1000,		/* (amount) acnl:  abandoned carriers number limit */\
+    0,			/* (bytes)  acfml: abandoned carrier fblk min limit */\
     /* --- Data not options -------------------------------------------- */\
     NULL,		/* (ptr)    fix                                  */\
     NULL		/* (ptr)    fix_type_size                        */\
@@ -151,6 +155,8 @@ typedef struct {
     128*1024,		/* (bytes)  smbcs:  smallest mbc size            */\
     10,			/* (amount) mbcgs:  mbc growth stages            */\
     0,			/* (%)      acul:  abandon carrier utilization limit */\
+    1000,		/* (amount) acnl:  abandoned carriers number limit */\
+    0,			/* (bytes)  acfml: abandoned carrier fblk min limit */\
     /* --- Data not options -------------------------------------------- */\
     NULL,		/* (ptr)    fix                                  */\
     NULL		/* (ptr)    fix_type_size                        */\
@@ -224,6 +230,8 @@ void  erts_alcu_literal_32_sys_dealloc(Allctr_t*, void *ptr, Uint size, int supe
 void erts_lcnt_update_allocator_locks(int enable);
 #endif
 
+int erts_alcu_try_set_dyn_param(Allctr_t*, Eterm param, Uint value);
+
 #endif /* !ERL_ALLOC_UTIL__ */
 
 #if defined(GET_ERL_ALLOC_UTIL_IMPL) && !defined(ERL_ALLOC_UTIL_IMPL__)
@@ -304,45 +312,8 @@ void erts_lcnt_update_allocator_locks(int enable);
 
 typedef union {char c[ERTS_ALLOC_ALIGN_BYTES]; long l; double d;} Unit_t;
 
-#ifdef ERTS_SMP
-
-typedef struct ErtsDoubleLink_t_ {
-    struct ErtsDoubleLink_t_ *next;
-    struct ErtsDoubleLink_t_ *prev;
-}ErtsDoubleLink_t;
-
-typedef struct {
-    erts_atomic_t next;
-    erts_atomic_t prev;
-    Allctr_t *orig_allctr;      /* read-only while carrier is alive */
-    ErtsThrPrgrVal thr_prgr;
-    erts_atomic_t max_size;
-    UWord abandon_limit;
-    UWord blocks;
-    UWord blocks_size;
-    ErtsDoubleLink_t abandoned; /* node in pooled_list or traitor_list */
-} ErtsAlcCPoolData_t;
-
-#endif
-
 typedef struct Carrier_t_ Carrier_t;
-struct Carrier_t_ {
-    UWord chdr;
-    Carrier_t *next;
-    Carrier_t *prev;
-    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;
-} CarrierList_t;
 
 typedef struct {
     UWord bhdr;
@@ -356,6 +327,22 @@ typedef struct {
 #endif
 } Block_t;
 
+typedef union ErtsAllctrDDBlock_t_ ErtsAllctrDDBlock_t;
+
+union ErtsAllctrDDBlock_t_ {
+    erts_atomic_t atmc_next;
+    ErtsAllctrDDBlock_t *ptr_next;
+};
+
+typedef struct {
+    Block_t blk;
+#if !MBC_ABLK_OFFSET_BITS
+    ErtsAllctrDDBlock_t umem_;
+#endif
+} ErtsFakeDDBlock_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)
@@ -364,14 +351,13 @@ typedef struct {
     (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().
+ * HOMECOMING_MBC_BLK_HDR is a special block header combo used for
+ * distinguishing 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 HOMECOMING_MBC_BLK_HDR (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)
+    (((B)->bhdr & FLG_MASK) == (THIS_FREE_BLK_HDR_FLG | LAST_BLK_HDR_FLG))
 
 #define IS_SBC_BLK(B) (((B)->bhdr & FLG_MASK) == SBC_BLK_HDR_FLG)
 #define IS_MBC_BLK(B) (!IS_SBC_BLK((B)))
@@ -395,6 +381,64 @@ typedef struct {
 
 typedef UWord FreeBlkFtr_t; /* Footer of a free block */
 
+/* This AOFF stuff really belong in erl_ao_firstfit_alloc.h */
+typedef struct AOFF_RBTree_t_ AOFF_RBTree_t;
+struct AOFF_RBTree_t_ {
+    Block_t hdr;
+    AOFF_RBTree_t *parent;
+    AOFF_RBTree_t *left;
+    AOFF_RBTree_t *right;
+    Uint32 flags;
+    Uint32 max_sz;  /* of all blocks in this sub-tree */
+};
+#ifdef ERTS_SMP
+void aoff_add_pooled_mbc(Allctr_t*, Carrier_t*);
+void aoff_remove_pooled_mbc(Allctr_t*, Carrier_t*);
+Carrier_t* aoff_lookup_pooled_mbc(Allctr_t*, Uint size);
+void erts_aoff_larger_max_size(AOFF_RBTree_t *node);
+#endif
+
+#ifdef ERTS_SMP
+
+typedef struct {
+    ErtsFakeDDBlock_t homecoming_dd;
+    erts_atomic_t next;
+    erts_atomic_t prev;
+    Allctr_t *orig_allctr;      /* read-only while carrier is alive */
+    ErtsThrPrgrVal thr_prgr;
+    erts_atomic_t max_size;
+    UWord abandon_limit;
+    UWord blocks;
+    UWord blocks_size;
+    enum {
+        ERTS_MBC_IS_HOME,
+        ERTS_MBC_WAS_POOLED,
+        ERTS_MBC_WAS_TRAITOR
+    } state;
+    AOFF_RBTree_t pooled;  /* node in pooled_tree */
+} ErtsAlcCPoolData_t;
+
+#endif
+
+struct Carrier_t_ {
+    UWord chdr;
+    Carrier_t *next;
+    Carrier_t *prev;
+    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;
+} CarrierList_t;
+
+
 typedef Uint64 CallCounter_t;
 
 typedef struct {
@@ -432,13 +476,6 @@ typedef struct {
 
 #ifdef ERTS_SMP
 
-typedef union ErtsAllctrDDBlock_t_ ErtsAllctrDDBlock_t;
-
-union ErtsAllctrDDBlock_t_ {
-    erts_atomic_t atmc_next;
-    ErtsAllctrDDBlock_t *ptr_next;
-};
-
 typedef struct {
     ErtsAllctrDDBlock_t marker;
     erts_atomic_t last;
@@ -553,26 +590,38 @@ struct Allctr_t_ {
     UWord               crr_set_flgs;
     UWord               crr_clr_flgs;
 
-    /* Carriers */
+    /* Carriers *employed* by this allocator */
     CarrierList_t	mbc_list;
     CarrierList_t	sbc_list;
 #ifdef ERTS_SMP
     struct {
-	/* pooled_list, traitor list and dc_list contain only
-           carriers _created_ by this allocator */
-	ErtsDoubleLink_t pooled_list;
-	ErtsDoubleLink_t traitor_list;
+	/* pooled_tree and dc_list contain only
+           carriers *created* by this allocator */
+	AOFF_RBTree_t*   pooled_tree;
 	CarrierList_t	 dc_list;
 
 	UWord		abandon_limit;
 	int		disable_abandon;
 	int		check_limit_count;
-	int		util_limit;
+	UWord		util_limit;       /* acul */
+        UWord           in_pool_limit;    /* acnl */
+        UWord           fblk_min_limit;   /* acmfl */
 	struct {
 	    erts_atomic_t	blocks_size;
 	    erts_atomic_t	no_blocks;
 	    erts_atomic_t	carriers_size;
 	    erts_atomic_t	no_carriers;
+            CallCounter_t       fail_pooled;
+            CallCounter_t       fail_shared;
+            CallCounter_t       fail_pend_dealloc;
+            CallCounter_t       fail;
+            CallCounter_t       fetch;
+	    CallCounter_t       skip_size;
+	    CallCounter_t       skip_busy;
+	    CallCounter_t       skip_not_pooled;
+	    CallCounter_t       skip_homecoming;
+	    CallCounter_t       skip_race;
+	    CallCounter_t       entrance_removed;
 	} stat;
     } cpool;
 #endif
@@ -607,6 +656,8 @@ struct Allctr_t_ {
     void*               (*sys_realloc)(Allctr_t *allctr, void *ptr, Uint *size_p, Uint old_size, int superalign);
     void                (*sys_dealloc)(Allctr_t *allctr, void *ptr, Uint size, int superalign);
 
+    int                 (*try_set_dyn_param)(Allctr_t*, Eterm param, Uint value);
+
     void		(*init_atoms)		(void);
 
 #ifdef ERTS_ALLOC_UTIL_HARD_DEBUG
diff --git a/erts/emulator/beam/erl_ao_firstfit_alloc.c b/erts/emulator/beam/erl_ao_firstfit_alloc.c
index 05ba1f9891..73576c0189 100644
--- a/erts/emulator/beam/erl_ao_firstfit_alloc.c
+++ b/erts/emulator/beam/erl_ao_firstfit_alloc.c
@@ -20,7 +20,7 @@
 
 
 /*
- * Description:	An "address order first fit" allocator
+ * Description:	A family of "first fit" allocator strategies
  *              based on a Red-Black (binary search) Tree. The search,
  *              insert, and delete operations are all O(log n) operations
  *              on a Red-Black Tree.
@@ -40,6 +40,10 @@
  *              sorting order. Blocks within the same carrier are sorted
  *              wrt size instead of address. The 'max_sz' field is maintained
  *              in order to dismiss entire carriers with too small blocks. 
+ * Age Order:
+ *      	Carriers are ordered by creation time instead of address.
+ *      	Oldest carrier with a large enough free block is chosen.
+ *      	No age order supported for blocks.
  *
  * Authors: 	Rickard Green/Sverker Eriksson
  */
@@ -53,10 +57,12 @@
 #include "erl_ao_firstfit_alloc.h"
 
 #ifdef DEBUG
+# define IS_DEBUG 1
 #if 0
 #define HARD_DEBUG
 #endif
 #else
+# define IS_DEBUG 0
 #undef HARD_DEBUG
 #endif
 
@@ -92,18 +98,6 @@
 #define RBT_ASSERT(x)
 #endif
 
-
-/* Types... */
-typedef struct AOFF_RBTree_t_ AOFF_RBTree_t;
-
-struct AOFF_RBTree_t_ {
-    Block_t hdr;
-    AOFF_RBTree_t *parent;
-    AOFF_RBTree_t *left;
-    AOFF_RBTree_t *right;
-    Uint32 flags;
-    Uint32 max_sz;  /* of all blocks in this sub-tree */
-};
 #define AOFF_BLK_SZ(B) MBC_FBLK_SZ(&(B)->hdr)
 
 /* BF block nodes keeps list of all with equal size
@@ -121,6 +115,7 @@ 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 */
+    Sint64 birth_time;
     AOFF_RBTree_t* root;        /* Root of my block tree */
 };
 #define RBT_NODE_TO_MBC(PTR) ErtsContainerStruct((PTR), AOFF_Carrier_t, rbt_node)
@@ -136,12 +131,12 @@ struct AOFF_Carrier_t_ {
 */
 
 #ifdef HARD_DEBUG
-#  define HARD_CHECK_IS_MEMBER(ROOT,NODE) rbt_assert_is_member(ROOT,NODE)
-#  define HARD_CHECK_TREE(CRR,FLV,ROOT,SZ) check_tree(CRR, FLV, ROOT, SZ)
-static AOFF_RBTree_t * check_tree(Carrier_t* within_crr, enum AOFF_Flavor flavor, AOFF_RBTree_t* root, Uint);
+#  define HARD_CHECK_IS_MEMBER(ROOT,NODE) ASSERT(rbt_is_member(ROOT,NODE))
+#  define HARD_CHECK_TREE(CRR,ORDER,ROOT,SZ) check_tree(CRR, ORDER, ROOT, SZ)
+static AOFF_RBTree_t * check_tree(Carrier_t*, enum AOFFSortOrder, AOFF_RBTree_t*, Uint);
 #else
 #  define HARD_CHECK_IS_MEMBER(ROOT,NODE)
-#  define HARD_CHECK_TREE(CRR,FLV,ROOT,SZ)
+#  define HARD_CHECK_TREE(CRR,ORDER,ROOT,SZ)
 #endif
 
 
@@ -179,25 +174,65 @@ static ERTS_INLINE void lower_max_size(AOFF_RBTree_t *node,
     else ASSERT(new_max == old_max);
 }
 
-static ERTS_INLINE SWord cmp_blocks(enum AOFF_Flavor flavor,
+#ifdef ERTS_SMP
+/*
+ * Set possibly new larger 'max_sz' of node and propagate change toward root
+ */
+void erts_aoff_larger_max_size(AOFF_RBTree_t *node)
+{
+    AOFF_RBTree_t* x = node;
+    const Uint new_sz = node->hdr.bhdr;
+
+    ASSERT(!x->left  || x->left->max_sz  <= x->max_sz);
+    ASSERT(!x->right || x->right->max_sz <= x->max_sz);
+
+    while (new_sz > x->max_sz) {
+        x->max_sz = new_sz;
+        x = x->parent;
+        if (!x)
+            break;
+    }
+}
+#endif
+
+/* Compare nodes for both carrier and block trees */
+static ERTS_INLINE SWord cmp_blocks(enum AOFFSortOrder order,
 				    AOFF_RBTree_t* lhs, AOFF_RBTree_t* rhs)
 {
     ASSERT(lhs != rhs);
-    ASSERT(flavor == AOFF_AOFF || FBLK_TO_MBC(&lhs->hdr) == FBLK_TO_MBC(&rhs->hdr));
-    if (flavor != AOFF_AOFF) {
-	SWord diff = (SWord)AOFF_BLK_SZ(lhs) - (SWord)AOFF_BLK_SZ(rhs);
-	if (diff || flavor == AOFF_BF) return diff;
+    if (order == FF_AGEFF) {
+	AOFF_Carrier_t* lc = RBT_NODE_TO_MBC(lhs);
+	AOFF_Carrier_t* rc = RBT_NODE_TO_MBC(rhs);
+	Sint64 diff = lc->birth_time - rc->birth_time;
+ #ifdef ARCH_64
+        if (diff)
+            return diff;
+ #else
+        if (diff < 0)
+            return -1;
+        else if (diff > 0)
+            return 1;
+ #endif
+    }
+    else {
+	ASSERT(order == FF_AOFF || FBLK_TO_MBC(&lhs->hdr) == FBLK_TO_MBC(&rhs->hdr));
+	if (order != FF_AOFF) {
+	    SWord diff = (SWord)AOFF_BLK_SZ(lhs) - (SWord)AOFF_BLK_SZ(rhs);
+	    if (diff || order == FF_BF) return diff;
+	}
     }
     return (char*)lhs - (char*)rhs;
 }
 
-static ERTS_INLINE SWord cmp_cand_blk(enum AOFF_Flavor flavor,
+/* Compare candidate block. Only for block tree */
+static ERTS_INLINE SWord cmp_cand_blk(enum AOFFSortOrder order,
 				      Block_t* cand_blk, AOFF_RBTree_t* rhs)
 {
-    if (flavor != AOFF_AOFF) {
+    ASSERT(order != FF_AGEFF);
+    if (order != FF_AOFF) {
 	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 || flavor == AOFF_BF) return diff;
+	    if (diff || order == FF_BF) return diff;
 	}
     }
     return (char*)cand_blk - (char*)rhs;
@@ -218,11 +253,8 @@ 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(enum AOFF_Flavor flavor, AOFF_RBTree_t** root, AOFF_RBTree_t* blk);
+static void rbt_insert(enum AOFFSortOrder, 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 *, fmtfn_t *, void *, Uint **, Uint *);
 static void init_atoms(void);
@@ -230,10 +262,17 @@ static void init_atoms(void);
 
 static int atoms_initialized = 0;
 
+#ifndef ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT
+static erts_atomic64_t birth_time_counter;
+#endif
+
 void
 erts_aoffalc_init(void)
 {
     atoms_initialized = 0;
+#ifndef ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT
+    erts_atomic64_init_nob(&birth_time_counter, 0);
+#endif
 }
 
 Allctr_t *
@@ -254,11 +293,12 @@ erts_aoffalc_start(AOFFAllctr_t *alc,
 
     sys_memcpy((void *) alc, (void *) &zero.allctr, sizeof(AOFFAllctr_t));
 
-    alc->flavor                         = aoffinit->flavor;
+    alc->blk_order                      = aoffinit->blk_order;
+    alc->crr_order                      = aoffinit->crr_order;
     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 = (aoffinit->flavor == AOFF_BF ?
+    allctr->min_block_size = (aoffinit->blk_order == FF_BF ?
 			      sizeof(AOFF_RBTreeList_t):sizeof(AOFF_RBTree_t));
 
     allctr->vsn_str			= ERTS_ALC_AOFF_ALLOC_VSN_STR;
@@ -487,9 +527,9 @@ aoff_unlink_free_block(Allctr_t *allctr, Block_t *blk)
     AOFF_Carrier_t *crr = (AOFF_Carrier_t*) FBLK_TO_MBC(&del->hdr);
 
     ASSERT(crr->rbt_node.hdr.bhdr == crr->root->max_sz);
-    HARD_CHECK_TREE(&crr->crr, alc->flavor, crr->root, 0);
+    HARD_CHECK_TREE(&crr->crr, alc->blk_order, crr->root, 0);
 
-    if (alc->flavor == AOFF_BF) {
+    if (alc->blk_order == FF_BF) {
 	ASSERT(del->flags & IS_BF_FLG);
 	if (IS_LIST_ELEM(del)) {
 	    /* Remove from list */
@@ -510,14 +550,14 @@ aoff_unlink_free_block(Allctr_t *allctr, Block_t *blk)
 	    
 	    replace(&crr->root, (AOFF_RBTree_t*)del, LIST_NEXT(del));
 	    
-	    HARD_CHECK_TREE(&crr->crr, alc->flavor, crr->root, 0);
+	    HARD_CHECK_TREE(&crr->crr, alc->blk_order, crr->root, 0);
 	    return;
 	}
     }
 
     rbt_delete(&crr->root, (AOFF_RBTree_t*)del);
 
-    HARD_CHECK_TREE(&crr->crr, alc->flavor, crr->root, 0);
+    HARD_CHECK_TREE(&crr->crr, alc->blk_order, crr->root, 0);
 
     /* Update the carrier tree with a potentially new (lower) max_sz
      */    
@@ -715,32 +755,33 @@ aoff_link_free_block(Allctr_t *allctr, Block_t *block)
 
     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_TREE(&blk_crr->crr, alc->flavor, blk_crr->root, 0);
+    HARD_CHECK_TREE(&blk_crr->crr, alc->blk_order, blk_crr->root, 0);
 
-    rbt_insert(alc->flavor, &blk_crr->root, blk);
+    rbt_insert(alc->blk_order, &blk_crr->root, blk);
 
-    /* Update the carrier tree with a potentially new (larger) max_sz
-    */
+    /*
+     * Update carrier tree with a potentially 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;
-	}
+        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->flavor, blk_crr->root, 0);
+    HARD_CHECK_TREE(NULL, alc->crr_order, alc->mbc_root, 0);
 }
 
 static void
-rbt_insert(enum AOFF_Flavor flavor, AOFF_RBTree_t** root, AOFF_RBTree_t* blk)
+rbt_insert(enum AOFFSortOrder order, AOFF_RBTree_t** root, AOFF_RBTree_t* blk)
 {
     Uint blk_sz = AOFF_BLK_SZ(blk);
 
 #ifdef DEBUG
-    blk->flags  = (flavor == AOFF_BF) ? IS_BF_FLG : 0; 
+    blk->flags  = (order == FF_BF) ? IS_BF_FLG : 0;
 #else
     blk->flags  = 0; 
 #endif
@@ -760,7 +801,7 @@ rbt_insert(enum AOFF_Flavor flavor, AOFF_RBTree_t** root, AOFF_RBTree_t* blk)
 	    if (x->max_sz < blk_sz) {
 		x->max_sz = blk_sz;
 	    }
-	    diff = cmp_blocks(flavor, blk, x);
+	    diff = cmp_blocks(order, blk, x);
 	    if (diff < 0) {
 		if (!x->left) {
 		    blk->parent = x;
@@ -778,7 +819,7 @@ rbt_insert(enum AOFF_Flavor flavor, AOFF_RBTree_t** root, AOFF_RBTree_t* blk)
 		x = x->right;
 	    }
 	    else {
-		ASSERT(flavor == AOFF_BF);
+		ASSERT(order == FF_BF);
 		ASSERT(blk->flags & IS_BF_FLG);			    
 		ASSERT(x->flags & IS_BF_FLG);			    
 		SET_LIST_ELEM(blk);
@@ -798,7 +839,7 @@ rbt_insert(enum AOFF_Flavor flavor, AOFF_RBTree_t** root, AOFF_RBTree_t* blk)
 	if (IS_RED(blk->parent))
 	    tree_insert_fixup(root, blk);
     }
-    if (flavor == AOFF_BF) {
+    if (order == FF_BF) {
 	SET_TREE_NODE(blk);
 	LIST_NEXT(blk) = NULL;
     }
@@ -826,6 +867,18 @@ rbt_search(AOFF_RBTree_t* root, Uint size)
     }
 }
 
+#ifdef ERTS_SMP
+Carrier_t* aoff_lookup_pooled_mbc(Allctr_t* allctr, Uint size)
+{
+    AOFF_RBTree_t* node;
+
+    if (!allctr->cpool.pooled_tree)
+	return NULL;
+    node = rbt_search(allctr->cpool.pooled_tree, size);
+    return node ? ErtsContainerStruct(node, Carrier_t, cpool.pooled) : NULL;
+}
+#endif
+
 static Block_t *
 aoff_get_free_block(Allctr_t *allctr, Uint size,
 		    Block_t *cand_blk, Uint cand_size)
@@ -850,7 +903,7 @@ aoff_get_free_block(Allctr_t *allctr, Uint size,
     /* Get block within carrier tree
      */
 #ifdef HARD_DEBUG
-    dbg_blk = HARD_CHECK_TREE(&crr->crr, alc->flavor, crr->root, size);
+    dbg_blk = HARD_CHECK_TREE(&crr->crr, alc->blk_order, crr->root, size);
 #endif
 
     blk = rbt_search(crr->root, size);
@@ -863,7 +916,7 @@ aoff_get_free_block(Allctr_t *allctr, Uint size,
     if (!blk)
 	return NULL;
 
-    if (cand_blk && cmp_cand_blk(alc->flavor, cand_blk, blk) < 0) {
+    if (cand_blk && cmp_cand_blk(alc->blk_order, cand_blk, blk) < 0) {
 	return NULL; /* cand_blk was better */
     }
 
@@ -872,23 +925,32 @@ aoff_get_free_block(Allctr_t *allctr, Uint size,
     return (Block_t *) blk;
 }
 
+static ERTS_INLINE Sint64 get_birth_time(void)
+{
+#ifdef ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT
+    return (Sint64) erts_os_monotonic_time();
+#else
+    return (Sint64) erts_atomic64_inc_read_nob(&birth_time_counter);
+#endif
+}
+
 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);
+    HARD_CHECK_TREE(NULL, alc->crr_order, *root, 0);
 
-    /* Link carrier in address order tree
-     */
     crr->rbt_node.hdr.bhdr = 0;
-    rbt_insert(AOFF_AOFF, root, &crr->rbt_node);
+    if (alc->crr_order == FF_AGEFF || IS_DEBUG)
+	crr->birth_time = get_birth_time();
+    rbt_insert(alc->crr_order, root, &crr->rbt_node);
 
     /* aoff_link_free_block will add free block later */
     crr->root = NULL;
 
-    HARD_CHECK_TREE(NULL, 0, *root, 0);
+    HARD_CHECK_TREE(NULL, alc->crr_order, *root, 0);
 }
 
 #define IS_CRR_IN_TREE(CRR,ROOT) \
@@ -911,27 +973,40 @@ static void aoff_add_mbc(Allctr_t *allctr, Carrier_t *carrier)
     AOFF_RBTree_t **root = &alc->mbc_root;
 
     ASSERT(!IS_CRR_IN_TREE(crr, *root));
-    HARD_CHECK_TREE(NULL, 0, *root, 0);   
+    HARD_CHECK_TREE(NULL, alc->crr_order, *root, 0);   
+
+    rbt_insert(alc->crr_order, root, &crr->rbt_node);
+
+    HARD_CHECK_TREE(NULL, alc->crr_order, *root, 0);
+}
+
+#ifdef ERTS_SMP
+void aoff_add_pooled_mbc(Allctr_t *allctr, Carrier_t *crr)
+{
+    AOFF_RBTree_t **root = &allctr->cpool.pooled_tree;
+
+    ASSERT(allctr == crr->cpool.orig_allctr);
+    HARD_CHECK_TREE(NULL, 0, *root, 0);
 
     /* Link carrier in address order tree
      */
-    rbt_insert(AOFF_AOFF, root, &crr->rbt_node);
+    rbt_insert(FF_AOFF, root, &crr->cpool.pooled);
 
     HARD_CHECK_TREE(NULL, 0, *root, 0);
 }
+#endif
 
 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;
+    AOFF_RBTree_t **root = &((AOFFAllctr_t*)allctr)->mbc_root;
+    AOFF_Carrier_t *crr = (AOFF_Carrier_t*)carrier;
 
     ASSERT(allctr == ERTS_ALC_CARRIER_TO_ALLCTR(carrier));
 
     if (!IS_CRR_IN_TREE(crr,*root))
-        return;
+	return;
 
-    HARD_CHECK_TREE(NULL, 0, *root, 0);
+    HARD_CHECK_TREE(NULL, alc->crr_order, *root, 0);
 
     rbt_delete(root, &crr->rbt_node);
     crr->rbt_node.parent = NULL;
@@ -939,8 +1014,28 @@ static void aoff_remove_mbc(Allctr_t *allctr, Carrier_t *carrier)
     crr->rbt_node.right = NULL;
     crr->rbt_node.max_sz = crr->rbt_node.hdr.bhdr;
 
-    HARD_CHECK_TREE(NULL, 0, *root, 0);
+    HARD_CHECK_TREE(NULL, alc->crr_order, *root, 0);
+}
+
+#ifdef ERTS_SMP
+void aoff_remove_pooled_mbc(Allctr_t *allctr, Carrier_t *crr)
+{
+    ASSERT(allctr == crr->cpool.orig_allctr);
+
+    HARD_CHECK_TREE(NULL, 0, allctr->cpool.pooled_tree, 0);
+
+    rbt_delete(&allctr->cpool.pooled_tree, &crr->cpool.pooled);
+#ifdef DEBUG
+    crr->cpool.pooled.parent = NULL;
+    crr->cpool.pooled.left = NULL;
+    crr->cpool.pooled.right = NULL;
+    crr->cpool.pooled.max_sz = 0;
+#endif
+    HARD_CHECK_TREE(NULL, 0, allctr->cpool.pooled_tree, 0);
+
 }
+#endif
+
 
 static UWord aoff_largest_fblk_in_mbc(Allctr_t* allctr, Carrier_t* carrier)
 {
@@ -955,17 +1050,17 @@ static UWord aoff_largest_fblk_in_mbc(Allctr_t* allctr, Carrier_t* carrier)
  * info_options()
  */
 
+static const char* flavor_str[2][3] = {
+    {"ageffcaoff", "ageffcaobf", "ageffcbf"},
+    {      "aoff",  "aoffcaobf",  "aoffcbf"}
+};
+static Eterm flavor_atoms[2][3];
+
 static struct {
     Eterm as;
-    Eterm aoff;
-    Eterm aoffcaobf;
-    Eterm aoffcbf;
-#ifdef DEBUG
-    Eterm end_of_atoms;
-#endif
 } am;
 
-static void ERTS_INLINE atom_init(Eterm *atom, char *name)
+static void ERTS_INLINE atom_init(Eterm *atom, const char *name)
 {
     *atom = am_atom_put(name, strlen(name));
 }
@@ -974,28 +1069,16 @@ static void ERTS_INLINE atom_init(Eterm *atom, char *name)
 static void
 init_atoms(void)
 {
-#ifdef DEBUG
-    Eterm *atom;
-#endif
+    int i, j;
 
     if (atoms_initialized)
 	return;
 
-#ifdef DEBUG
-    for (atom = (Eterm *) &am; atom <= &am.end_of_atoms; atom++) {
-	*atom = THE_NON_VALUE;
-    }
-#endif
     AM_INIT(as);
-    AM_INIT(aoff);
-    AM_INIT(aoffcaobf);
-    AM_INIT(aoffcbf);
 
-#ifdef DEBUG
-    for (atom = (Eterm *) &am; atom < &am.end_of_atoms; atom++) {
-	ASSERT(*atom != THE_NON_VALUE);
-    }
-#endif
+    for (i = 0; i < 2; i++)
+        for (j = 0; j < 3; j++)
+            atom_init(&flavor_atoms[i][j], flavor_str[i][j]);
 
     atoms_initialized = 1;
 }
@@ -1021,15 +1104,16 @@ info_options(Allctr_t *allctr,
 {
     AOFFAllctr_t* alc = (AOFFAllctr_t*) allctr;
     Eterm res = THE_NON_VALUE;
-    const char* flavor_str[3] = {"aoff", "aoffcaobf", "aoffcbf"};
-    Eterm flavor_atom[3] = {am.aoff, am.aoffcaobf, am.aoffcbf};
+
+    ASSERT(alc->crr_order >= 0 && alc->crr_order <= 1);
+    ASSERT(alc->blk_order >= 1 && alc->blk_order <= 3);
 
     if (print_to_p) {
 	erts_print(*print_to_p,
 		   print_to_arg,
 		   "%sas: %s\n",
 		   prefix,
-		   flavor_str[alc->flavor]);
+		   flavor_str[alc->crr_order][alc->blk_order-1]);
     }
 
     if (hpp || szp) {
@@ -1039,7 +1123,8 @@ info_options(Allctr_t *allctr,
 		     __FILE__, __LINE__);;
 
 	res = NIL;
-	add_2tup(hpp, szp, &res, am.as, flavor_atom[alc->flavor]);
+	add_2tup(hpp, szp, &res, am.as,
+                 flavor_atoms[alc->crr_order][alc->blk_order-1]);
     }
 
     return res;
@@ -1057,7 +1142,7 @@ UWord
 erts_aoffalc_test(UWord op, UWord a1, UWord a2)
 {
     switch (op) {
-    case 0x500: return (UWord) ((AOFFAllctr_t *) a1)->flavor == AOFF_AOBF;
+    case 0x500: return (UWord) ((AOFFAllctr_t *) a1)->blk_order == FF_AOBF;
     case 0x501: {
 	AOFF_RBTree_t *node = ((AOFFAllctr_t *) a1)->mbc_root; 
 	Uint size = (Uint) a2;
@@ -1072,7 +1157,7 @@ erts_aoffalc_test(UWord op, UWord a1, UWord a2)
     case 0x507:	return (UWord) IS_TREE_NODE((AOFF_RBTree_t *) a1);
     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)->flavor == AOFF_BF;
+    case 0x50a: return (UWord) ((AOFFAllctr_t *) a1)->blk_order == FF_BF;
     case 0x50b:	return (UWord) LIST_PREV(a1);
     default:	ASSERT(0); return ~((UWord) 0);
     }
@@ -1085,12 +1170,13 @@ 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)
+static int rbt_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);
+        if (!node->parent || (node->parent->left != node &&
+                              node->parent->right != node)) {
+            return 0;
+        }
 	node = node->parent;
     }    
     return 1;
@@ -1132,7 +1218,7 @@ static void print_tree(AOFF_RBTree_t*);
  */
 
 static AOFF_RBTree_t *
-check_tree(Carrier_t* within_crr, enum AOFF_Flavor flavor, AOFF_RBTree_t* root, Uint size)
+check_tree(Carrier_t* within_crr, enum AOFFSortOrder order, AOFF_RBTree_t* root, Uint size)
 {
     AOFF_RBTree_t *res = NULL;
     Sint blacks;
@@ -1144,7 +1230,8 @@ check_tree(Carrier_t* within_crr, enum AOFF_Flavor flavor, AOFF_RBTree_t* root,
 #ifdef PRINT_TREE
     print_tree(root);
 #endif
-    ASSERT(within_crr || flavor == AOFF_AOFF);
+    ASSERT((within_crr && order >= FF_AOFF) ||
+           (!within_crr && order <= FF_AOFF));
 
     if (!root)
 	return res;
@@ -1202,7 +1289,7 @@ check_tree(Carrier_t* within_crr, enum AOFF_Flavor flavor, AOFF_RBTree_t* root,
 	    ASSERT(((char*)x + AOFF_BLK_SZ(x)) <= ((char*)crr + CARRIER_SZ(crr)));
 
 	}
-	if (flavor == AOFF_BF) {
+	if (order == FF_BF) {
 	    AOFF_RBTree_t* y = x;
 	    AOFF_RBTree_t* nxt = LIST_NEXT(y);
 	    ASSERT(IS_TREE_NODE(x));
@@ -1225,13 +1312,13 @@ check_tree(Carrier_t* within_crr, enum AOFF_Flavor flavor, AOFF_RBTree_t* root,
 
 	if (x->left) {
 	    ASSERT(x->left->parent == x);
-	    ASSERT(cmp_blocks(flavor, x->left, x) < 0);
+	    ASSERT(cmp_blocks(order, x->left, x) < 0);
 	    ASSERT(x->left->max_sz <= x->max_sz);	    
 	}
 
 	if (x->right) {
 	    ASSERT(x->right->parent == x);
-	    ASSERT(cmp_blocks(flavor, x->right, x) > 0);
+	    ASSERT(cmp_blocks(order, x->right, x) > 0);
 	    ASSERT(x->right->max_sz <= x->max_sz);	    
 	}
 	ASSERT(x->max_sz >= AOFF_BLK_SZ(x));
@@ -1240,7 +1327,7 @@ check_tree(Carrier_t* within_crr, enum AOFF_Flavor flavor, AOFF_RBTree_t* root,
 	       || x->max_sz == (x->right ? x->right->max_sz : 0));
 
 	if (size && AOFF_BLK_SZ(x) >= size) {
-	    if (!res || cmp_blocks(flavor, x, res) < 0) {
+	    if (!res || cmp_blocks(order, x, res) < 0) {
 		res = x;
 	    }
 	}
diff --git a/erts/emulator/beam/erl_ao_firstfit_alloc.h b/erts/emulator/beam/erl_ao_firstfit_alloc.h
index 7349c6ab19..9cf4fc81a8 100644
--- a/erts/emulator/beam/erl_ao_firstfit_alloc.h
+++ b/erts/emulator/beam/erl_ao_firstfit_alloc.h
@@ -28,14 +28,16 @@
 
 typedef struct AOFFAllctr_t_ AOFFAllctr_t;
 
-enum AOFF_Flavor {
-    AOFF_AOFF = 0,
-    AOFF_AOBF = 1,
-    AOFF_BF   = 2
+enum AOFFSortOrder {
+    FF_AGEFF = 0,
+    FF_AOFF  = 1,
+    FF_AOBF  = 2,
+    FF_BF    = 3
 };
 
 typedef struct {
-    enum AOFF_Flavor flavor;
+    enum AOFFSortOrder blk_order;
+    enum AOFFSortOrder crr_order;
 } AOFFAllctrInit_t;
 
 #define ERTS_DEFAULT_AOFF_ALLCTR_INIT {0/*dummy*/}
@@ -53,12 +55,12 @@ Allctr_t *erts_aoffalc_start(AOFFAllctr_t *, AOFFAllctrInit_t*, AllctrInit_t *);
 #define GET_ERL_ALLOC_UTIL_IMPL
 #include "erl_alloc_util.h"
 
-
 struct AOFFAllctr_t_ {
     Allctr_t		allctr; /* Has to be first! */
 
     struct AOFF_RBTree_t_* mbc_root;
-    enum AOFF_Flavor flavor;
+    enum AOFFSortOrder blk_order;
+    enum AOFFSortOrder crr_order;
 };
 
 UWord erts_aoffalc_test(UWord, UWord, UWord);
diff --git a/erts/emulator/beam/erl_goodfit_alloc.c b/erts/emulator/beam/erl_goodfit_alloc.c
index 50aa41b4d2..a38f6c7daf 100644
--- a/erts/emulator/beam/erl_goodfit_alloc.c
+++ b/erts/emulator/beam/erl_goodfit_alloc.c
@@ -170,6 +170,7 @@ 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 *, fmtfn_t *,
 						 void *, Uint **, Uint *);
+static int        gfalc_try_set_dyn_param(Allctr_t*, Eterm param, Uint value);
 static void		init_atoms		(void);
 
 #ifdef ERTS_ALLOC_UTIL_HARD_DEBUG
@@ -250,6 +251,8 @@ erts_gfalc_start(GFAllctr_t *gfallctr,
     if (!erts_alcu_start(allctr, init))
 	return NULL;
 
+    allctr->try_set_dyn_param = gfalc_try_set_dyn_param;
+
     if (allctr->min_block_size != MIN_BLK_SZ)
 	return NULL;
 
@@ -584,6 +587,15 @@ info_options(Allctr_t *allctr,
     return res;
 }
 
+static int gfalc_try_set_dyn_param(Allctr_t* allctr, Eterm param, Uint value)
+{
+    if (param == am_sbct) {
+        /* Cannot change 'sbct' without rearranging buckets */
+        return 0;
+    }
+    return erts_alcu_try_set_dyn_param(allctr, param, value);
+}
+
 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *\
  * NOTE:  erts_gfalc_test() is only supposed to be used for testing.         *
  *                                                                           *