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

3 files changed, 126 insertions, 12 deletions

diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml
index 69af7430f1..3ed0f59b7d 100644
--- a/erts/doc/src/erlang.xml
+++ b/erts/doc/src/erlang.xml
@@ -6942,6 +6942,23 @@ ok
 
     <func>
       <name name="system_flag" arity="2" clause_i="4"/>
+      <fsummary>Set system flag for erts_alloc.</fsummary>
+      <desc>
+        <p>Sets system flags for
+	<seealso marker="erts:erts_alloc"><c>erts_alloc(3)</c></seealso>.
+        <c><anno>Alloc</anno></c> is the allocator to affect, for example
+	<c>binary_alloc</c>. <c><anno>F</anno></c> is the flag to change and
+	<c><anno>V</anno></c> is the new value.</p>
+	<p>Only a subset of all <c>erts_alloc</c> flags can be changed
+	at run time. This subset is currently only the flag
+	<seealso marker="erts:erts_alloc#M_sbct"><c>sbct</c></seealso>.</p>
+        <p>Returns <c>ok</c> if the flag was set or <c>notsup</c> if not
+	supported by <c>erts_alloc</c>.</p>
+      </desc>
+    </func>
+
+    <func>
+      <name name="system_flag" arity="2" clause_i="5"/>
       <fsummary>Set system flag fullsweep_after.</fsummary>
       <desc>
         <p>Sets system flag <c>fullsweep_after</c>.
@@ -6960,7 +6977,7 @@ ok
     </func>
 
     <func>
-      <name name="system_flag" arity="2" clause_i="5"/>
+      <name name="system_flag" arity="2" clause_i="6"/>
       <fsummary>Set system flag microstate_accounting.</fsummary>
       <desc>
         <p><marker id="system_flag_microstate_accounting"></marker>
@@ -6973,7 +6990,7 @@ ok
     </func>
 
     <func>
-      <name name="system_flag" arity="2" clause_i="6"/>
+      <name name="system_flag" arity="2" clause_i="7"/>
       <fsummary>Set system flag min_heap_size.</fsummary>
       <desc>
         <p>Sets the default minimum heap size for processes. The size
@@ -6988,7 +7005,7 @@ ok
     </func>
 
     <func>
-      <name name="system_flag" arity="2" clause_i="7"/>
+      <name name="system_flag" arity="2" clause_i="8"/>
       <fsummary>Set system flag min_bin_vheap_size.</fsummary>
       <desc>
         <p>Sets the default minimum binary virtual heap size for
@@ -7005,7 +7022,7 @@ ok
     </func>
 
     <func>
-      <name name="system_flag" arity="2" clause_i="8"/>
+      <name name="system_flag" arity="2" clause_i="9"/>
       <fsummary>Set system flag max_heap_size.</fsummary>
       <type name="max_heap_size"/>
       <desc>
@@ -7023,7 +7040,7 @@ ok
     </func>
 
     <func>
-      <name name="system_flag" arity="2" clause_i="9"/>
+      <name name="system_flag" arity="2" clause_i="10"/>
       <fsummary>Set system flag multi_scheduling.</fsummary>
       <desc>
         <p><marker id="system_flag_multi_scheduling"></marker>
@@ -7078,7 +7095,7 @@ ok
     </func>
 
     <func>
-      <name name="system_flag" arity="2" clause_i="10"/>
+      <name name="system_flag" arity="2" clause_i="11"/>
       <fsummary>Set system flag scheduler_bind_type.</fsummary>
       <type name="scheduler_bind_type"/>
       <desc>
@@ -7204,7 +7221,7 @@ ok
     </func>
 
     <func>
-      <name name="system_flag" arity="2" clause_i="11"/>
+      <name name="system_flag" arity="2" clause_i="12"/>
       <fsummary>Set system flag scheduler_wall_time.</fsummary>
       <desc>
         <p><marker id="system_flag_scheduler_wall_time"></marker>
@@ -7216,7 +7233,7 @@ ok
     </func>
 
     <func>
-      <name name="system_flag" arity="2" clause_i="12"/>
+      <name name="system_flag" arity="2" clause_i="13"/>
       <fsummary>Set system flag schedulers_online.</fsummary>
       <desc>
         <p><marker id="system_flag_schedulers_online"></marker>
@@ -7244,7 +7261,7 @@ ok
     </func>
 
     <func>
-      <name name="system_flag" arity="2" clause_i="13"/>
+      <name name="system_flag" arity="2" clause_i="14"/>
       <fsummary>Set system flag trace_control_word.</fsummary>
       <desc>
         <p>Sets the value of the node trace control word to
@@ -7258,7 +7275,7 @@ ok
     </func>
 
     <func>
-      <name name="system_flag" arity="2" clause_i="14"/>
+      <name name="system_flag" arity="2" clause_i="15"/>
       <fsummary>Finalize the time offset.</fsummary>
       <desc>
         <p><marker id="system_flag_time_offset"></marker>
diff --git a/erts/doc/src/erts_alloc.xml b/erts/doc/src/erts_alloc.xml
index d3f725ef99..ce8d75f350 100644
--- a/erts/doc/src/erts_alloc.xml
+++ b/erts/doc/src/erts_alloc.xml
@@ -225,6 +225,33 @@
           used. The time complexity is proportional to log N, where
           N is the number of free blocks.</p>
       </item>
+      <tag>Age order first fit carrier address order first fit</tag>
+      <item>
+	<p>Strategy: Find the <em>oldest carrier</em> that
+          can satisfy the requested block size, then find a block within
+          that carrier using the "address order first fit" strategy.</p>
+        <p>Implementation: A balanced binary search tree is
+          used. The time complexity is proportional to log N, where
+          N is the number of free blocks.</p>
+      </item>
+      <tag>Age order first fit carrier best fit</tag>
+      <item>
+        <p>Strategy: Find the <em>oldest carrier</em> that
+          can satisfy the requested block size, then find a block within
+          that carrier using the "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>Age order first fit carrier address order best fit</tag>
+      <item>
+        <p>Strategy: Find the <em>oldest carrier</em> that
+          can satisfy the requested block size, then find a block within
+          that carrier using the "address 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
@@ -467,7 +494,8 @@
             fetched, it will function as an ordinary carrier. This feature has
             special requirements on the
             <seealso marker="#M_as">allocation strategy</seealso> used. Only
-            the strategies <c>aoff</c>, <c>aoffcbf</c>, and <c>aoffcaobf</c>
+            the strategies <c>aoff</c>, <c>aoffcbf</c>, <c>aoffcaobf</c>,
+	    <c>ageffcaoff</c>m, <c>ageffcbf</c> and <c>ageffcaobf</c>
             support abandoned carriers.</p>
           <p>This feature also requires
             <seealso marker="#M_t">multiple thread specific instances</seealso>
@@ -478,8 +506,30 @@
             allocators based on the <c>alloc_util</c> framework, except
             <c>temp_alloc</c> (which would be pointless).</p>
         </item>
+
+	<tag><marker id="M_acfml"/><c><![CDATA[+M<S>acfml <bytes>]]></c>
+        </tag>
+        <item>
+          <p>Abandon carrier free block min limit. A valid <c><![CDATA[<bytes>]]></c>
+            is a positive integer representing a block size limit. The largest
+	    free block in a carrier must be at least <c>bytes</c> large, for the
+	    carrier to be abandoned. The default is zero but can be changed
+	    in the future.</p>
+	  <p>See also <seealso marker="#M_acul"><c>acul</c></seealso>.</p>
+        </item>
+
+        <tag><marker id="M_acnl"/><c><![CDATA[+M<S>acnl <amount>]]></c>
+        </tag>
+        <item>
+          <p>Abandon carrier number limit. A valid <c><![CDATA[<amount>]]></c>
+            is a positive integer representing max number of abandoned carriers per
+	    allocator instance. Defaults to 1000 which will practically disable
+	    the limit, but this can be changed in the future.</p>
+	  <p>See also <seealso marker="#M_acul"><c>acul</c></seealso>.</p>
+        </item>
+
         <tag><marker id="M_as"/>
-          <c><![CDATA[+M<S>as bf|aobf|aoff|aoffcbf|aoffcaobf|gf|af]]></c></tag>
+          <c><![CDATA[+M<S>as bf|aobf|aoff|aoffcbf|aoffcaobf|ageffcaoff|ageffcbf|ageffcaobf|gf|af]]></c></tag>
         <item>
           <p>Allocation strategy. The following strategies are valid:</p>
           <list type="bulleted">
@@ -490,6 +540,11 @@
             </item>
             <item><c>aoffcaobf</c> (address order first fit carrier address
               order best fit)</item>
+            <item><c>ageffcaoff</c> (age order first fit carrier address order first fit)</item>
+            <item><c>ageffcbf</c> (age order first fit carrier best fit)
+            </item>
+            <item><c>ageffcaobf</c> (age order first fit carrier address
+              order best fit)</item>
             <item><c>gf</c> (good fit)</item>
             <item><c>af</c> (a fit)</item>
           </list>
diff --git a/erts/doc/src/notes.xml b/erts/doc/src/notes.xml
index 39dd90b8a0..f62788d2d8 100644
--- a/erts/doc/src/notes.xml
+++ b/erts/doc/src/notes.xml
@@ -31,6 +31,48 @@
   </header>
   <p>This document describes the changes made to the ERTS application.</p>
 
+<section><title>Erts 9.2.1</title>
+
+    <section><title>Improvements and New Features</title>
+      <list>
+        <item>
+          <p>
+	    Improve search algorithm of abandoned memory carriers.
+	    Instead of limited linear search, each allocator instance
+	    maintain a balanced search tree of all its abandoned
+	    carriers for faster and more exhaustive search.</p>
+          <p>
+	    Own Id: OTP-14915 Aux Id: ERIERL-88 </p>
+        </item>
+        <item>
+          <p>
+	    New erts_alloc command line options <c>+M_acnl</c> and
+	    <c>+M_acfml</c> to limit carrier abandonment.</p>
+          <p>
+	    Own Id: OTP-14916 Aux Id: ERIERL-88 </p>
+        </item>
+        <item>
+          <p>
+	    New family of <c>erts_alloc</c> strategies: Age Order
+	    First Fit. Similar to "address order", but instead the
+	    oldest possible carrier is always chosen for allocation.</p>
+          <p>
+	    Own Id: OTP-14917 Aux Id: ERIERL-88 </p>
+        </item>
+        <item>
+          <p>
+	    Add possibility to change allocator options at runtime
+	    with <c>system_info(erts_alloc, ...)</c>. Only option
+	    <c>sbct</c> (single block carrier threshold) is currently
+	    supported via this interface.</p>
+          <p>
+	    Own Id: OTP-14918 Aux Id: ERIERL-88 </p>
+        </item>
+      </list>
+    </section>
+
+</section>
+
 <section><title>Erts 9.2</title>
 
     <section><title>Fixed Bugs and Malfunctions</title>