Merge branch 'master' into sverk/master/halt-INT_MIN

1 files changed, 450 insertions, 29 deletions

diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml
index 7926157fa5..1f8e89768c 100644
--- a/erts/doc/src/erlang.xml
+++ b/erts/doc/src/erlang.xml
@@ -59,6 +59,12 @@
     </datatype>
 
     <datatype>
+      <name name="message_queue_data"></name>
+      <desc><p>See <seealso marker="#process_flag_message_queue_data"><c>erlang:process_flag(message_queue_data, MQD)</c></seealso>.</p>
+      </desc>
+    </datatype>
+
+    <datatype>
       <name name="timestamp"></name>
       <desc><p>See <seealso marker="#timestamp/0">erlang:timestamp/0</seealso>.</p>
       </desc>
@@ -125,6 +131,17 @@
 	  </note>
 	  </item>
 
+	  <tag><c>perf_counter</c></tag>
+	  <item><p>Symbolic representation of the performance counter
+          time unit used by the Erlang runtime system.</p>
+
+          <p>The <c>perf_counter</c> time unit behaves much in the same way
+          as the <c>native</c> time unit. That is it might differ inbetween
+          run-time restarts. You get values of this type by calling
+          <seealso marker="kernel:os#perf_counter/0"><c>os:perf_counter()</c></seealso>
+          </p>
+          </item>
+
 	</taglist>
 
 	<p>The <c>time_unit/0</c> type may be extended. Use
@@ -1105,7 +1122,7 @@
       <fsummary>Prints a term on standard output.</fsummary>
       <desc>
         <p>Prints a text representation of <c><anno>Term</anno></c> on the
-          standard output. On OSE, the term is printed to the ramlog.</p>
+          standard output.</p>
         <warning>
           <p>This BIF is intended for debugging only.</p>
         </warning>
@@ -4281,9 +4298,59 @@ os_prompt% </pre>
         <p>Returns the old value of the flag.</p>
       </desc>
     </func>
-
+    <marker id="process_flag_message_queue_data"/>
     <func>
       <name name="process_flag" arity="2" clause_i="5"/>
+      <fsummary>Set process flag <c>message_queue_data</c> for the calling process</fsummary>
+      <type name="message_queue_data"/>
+      <desc>
+	<p>This flag determines how messages in the message queue
+	are stored. When the flag is:</p>
+        <taglist>
+          <tag><c>off_heap</c></tag>
+	  <item><p>
+	    <em>All</em> messages in the message queue will be stored
+	    outside of the process heap. This implies that <em>no</em>
+	    messages in the message queue will be part of a garbage
+	    collection of the process.
+	  </p></item>
+          <tag><c>on_heap</c></tag>
+	  <item><p>
+	    All messages in the message queue will eventually be
+	    placed on heap. They may however temporarily be stored
+	    off heap. This is how messages always have been stored
+	    up until ERTS version 8.0.
+	  </p></item>
+          <tag><c>mixed</c></tag>
+	  <item><p>
+	    Messages may be placed either on the heap or outside
+	    of the heap.
+	  </p></item>
+        </taglist>
+	<p>
+	  The default <c>message_queue_data</c> process flag is determined
+	  by the <seealso marker="erl#+xmqd"><c>+xmqd</c></seealso>
+	  <c>erl</c> command line argument.
+	</p>
+	<p>
+	  If the process potentially may get a hugh amount of messages,
+	  you are recommended to set the flag to <c>off_heap</c>. This
+	  since a garbage collection with lots of messages placed on
+	  the heap may become extremly expensive and the process may
+	  consume large amounts of memory. Performance of the
+	  actual message passing is however generally better when not
+	  using the <c>off_heap</c> flag.
+	</p>
+	<p>
+	  When changing this flag messages will be moved. This work
+	  has been initiated but not completed when this function
+	  call returns.
+	</p>
+        <p>Returns the old value of the flag.</p>
+      </desc>
+    </func>
+    <func>
+      <name name="process_flag" arity="2" clause_i="6"/>
       <fsummary>Sets process flag <c>priority</c> for the calling process.</fsummary>
       <type name="priority_level"/>
       <desc>
@@ -4357,7 +4424,7 @@ os_prompt% </pre>
     </func>
 
     <func>
-      <name name="process_flag" arity="2" clause_i="6"/>
+      <name name="process_flag" arity="2" clause_i="7"/>
       <fsummary>Sets process flag <c>save_calls</c> for the calling process.</fsummary>
       <desc>
         <p><c><anno>N</anno></c> must be an integer in the interval 0..10000.
@@ -4388,7 +4455,7 @@ os_prompt% </pre>
     </func>
 
     <func>
-      <name name="process_flag" arity="2" clause_i="7"/>
+      <name name="process_flag" arity="2" clause_i="8"/>
       <fsummary>Sets process flag <c>sensitive</c> for the calling process.</fsummary>
       <desc>
         <p>Sets or clears flag <c>sensitive</c> for the current process.
@@ -4442,6 +4509,7 @@ os_prompt% </pre>
       <type name="process_info_result_item"/>
       <type name="priority_level"/>
       <type name="stack_item"/>
+      <type name="message_queue_data" />
       <desc>
         <p>Returns a list containing <c><anno>InfoTuple</anno></c>s with
 	  miscellaneous information about the process identified by
@@ -4494,6 +4562,7 @@ os_prompt% </pre>
       <type name="process_info_result_item"/>
       <type name="stack_item"/>
       <type name="priority_level"/>
+      <type name="message_queue_data" />
       <desc>
         <p>Returns information about the process identified by
            <c><anno>Pid</anno></c>, as specified by
@@ -4585,6 +4654,17 @@ os_prompt% </pre>
 	       The content of <c><anno>GCInfo</anno></c> can be changed without
 	       prior notice.</p>
           </item>
+          <tag><c>{garbage_collection_info, <anno>GCInfo</anno>}</c></tag>
+          <item>
+            <p><c><anno>GCInfo</anno></c> is a list containing miscellaneous
+	       detailed information about garbage collection for this process.
+	       The content of <c><anno>GCInfo</anno></c> can be changed without
+	       prior notice.
+               See <seealso marker="#gc_start">gc_start</seealso> in
+               <seealso marker="#trace/3">erlang:trace/3</seealso> for details about
+               what each item means.
+            </p>
+          </item>
           <tag><c>{group_leader, <anno>GroupLeader</anno>}</c></tag>
           <item>
             <p><c><anno>GroupLeader</anno></c> is group leader for the I/O of
@@ -4662,6 +4742,15 @@ os_prompt% </pre>
               monitor by name, the list item is
               <c>{process, {<anno>RegName</anno>, <anno>Node</anno>}}</c>.</p>
           </item>
+          <tag><c>{message_queue_data, <anno>MQD</anno>}</c></tag>
+          <item>
+            <p>Returns the current state of the <c>message_queue_data</c>
+	    process flag. <c><anno>MQD</anno></c> is either <c>off_heap</c>,
+	    <c>on_heap</c>, or <c>mixed</c>. For more information, see the
+	    documentation of
+            <seealso marker="#process_flag_message_queue_data"><c>process_flag(message_queue_data,
+	    MQD)</c></seealso>.</p>
+          </item>
           <tag><c>{priority, <anno>Level</anno>}</c></tag>
           <item>
             <p><c><anno>Level</anno></c> is the current priority level for
@@ -4804,6 +4893,12 @@ os_prompt% </pre>
             <seealso marker="kernel:code">code(3)</seealso>)
             and is not to be used elsewhere.</p>
         </warning>
+        <note>
+	  <p>As from <c>ERTS</c> 8.0 (OTP 19), any lingering processes
+	   that still execute the old code will be killed by this function.
+	   In earlier versions, such incorrect use could cause much
+	   more fatal failures, like emulator crash.</p>
+        </note>
         <p>Failure: <c>badarg</c> if there is no old code for
           <c><anno>Module</anno></c>.</p>
       </desc>
@@ -5430,6 +5525,8 @@ true</pre>
       <name name="spawn_opt" arity="2"/>
       <fsummary>Creates a new process with a fun as entry point.</fsummary>
       <type name="priority_level"/>
+      <type name="message_queue_data" />
+      <type name="spawn_opt_option" />
       <desc>
         <p>Returns the process identifier (pid) of a new process
           started by the application of <c><anno>Fun</anno></c>
@@ -5445,6 +5542,8 @@ true</pre>
       <name name="spawn_opt" arity="3"/>
       <fsummary>Creates a new process with a fun as entry point on a given node.</fsummary>
       <type name="priority_level"/>
+      <type name="message_queue_data" />
+      <type name="spawn_opt_option" />
       <desc>
         <p>Returns the process identifier (pid) of a new process started
           by the application of <c><anno>Fun</anno></c> to the
@@ -5459,6 +5558,8 @@ true</pre>
       <name name="spawn_opt" arity="4"/>
       <fsummary>Creates a new process with a function as entry point.</fsummary>
       <type name="priority_level"/>
+      <type name="message_queue_data" />
+      <type name="spawn_opt_option" />
       <desc>
         <p>Works as
           <seealso marker="#spawn/3">spawn/3</seealso>, except that an
@@ -5560,6 +5661,18 @@ true</pre>
               fine-tuning an application and to measure the execution
               time with various <c><anno>VSize</anno></c> values.</p>
           </item>
+          <tag><c>{message_queue_data, <anno>MQD</anno>}</c></tag>
+          <item>
+            <p>Sets the state of the <c>message_queue_data</c> process
+	    flag. <c><anno>MQD</anno></c> should be either <c>off_heap</c>,
+	    <c>on_heap</c>, or <c>mixed</c>. The default
+	    <c>message_queue_data</c> process flag is determined by the
+	    <seealso marker="erl#+xmqd"><c>+xmqd</c></seealso> <c>erl</c>
+	    command line argument. For more information, see the
+	    documentation of
+            <seealso marker="#process_flag_message_queue_data"><c>process_flag(message_queue_data,
+	    <anno>MQD</anno>)</c></seealso>.</p>
+          </item>
         </taglist>
       </desc>
     </func>
@@ -5568,6 +5681,8 @@ true</pre>
       <name name="spawn_opt" arity="5"/>
       <fsummary>Creates a new process with a function as entry point on a given node.</fsummary>
       <type name="priority_level"/>
+      <type name="message_queue_data" />
+      <type name="spawn_opt_option" />
       <desc>
         <p>Returns the process identifier (pid) of a new process started
           by the application
@@ -5685,8 +5800,31 @@ true</pre>
 	<anno>Dest</anno>, <anno>Msg</anno>, [])</c></seealso>.</p>
       </desc>
     </func>
+
     <func>
       <name name="statistics" arity="1" clause_i="1"/>
+      <fsummary>Information about active processes and ports.</fsummary>
+      <desc><marker id="statistics_active_tasks"></marker>
+	<p>
+	  Returns a list where each element represents the amount
+	  of active processes and ports on each run queue and its
+	  associated scheduler. That is, the number of processes and
+	  ports that are ready to run, or are currently running. The
+	  element location in the list corresponds to the scheduler
+	  and its run queue. The first element corresponds to scheduler
+	  number 1 and so on. The information is <em>not</em> gathered
+	  atomically. That is, the result is not necessarily a
+	  consistent snapshot of the state, but instead quite
+	  efficiently gathered. See also,
+	  <seealso marker="#statistics_total_active_tasks"><c>statistics(total_active_tasks)</c></seealso>,
+	  <seealso marker="#statistics_run_queue_lengths"><c>statistics(run_queue_lengths)</c></seealso>, and
+	  <seealso marker="#statistics_total_run_queue_lengths"><c>statistics(total_run_queue_lengths)</c></seealso>.
+	</p>
+      </desc>
+    </func>
+
+    <func>
+      <name name="statistics" arity="1" clause_i="2"/>
       <fsummary>Information about context switches.</fsummary>
       <desc>
         <p>Returns the total number of context switches since the
@@ -5695,7 +5833,7 @@ true</pre>
     </func>
 
     <func>
-      <name name="statistics" arity="1" clause_i="2"/>
+      <name name="statistics" arity="1" clause_i="3"/>
       <fsummary>Information about exact reductions.</fsummary>
       <desc>
         <marker id="statistics_exact_reductions"></marker>
@@ -5709,7 +5847,7 @@ true</pre>
     </func>
 
     <func>
-      <name name="statistics" arity="1" clause_i="3"/>
+      <name name="statistics" arity="1" clause_i="4"/>
       <fsummary>Information about garbage collection.</fsummary>
       <desc>
         <p>Returns information about garbage collection, for example:</p>
@@ -5721,7 +5859,7 @@ true</pre>
     </func>
 
     <func>
-      <name name="statistics" arity="1" clause_i="4"/>
+      <name name="statistics" arity="1" clause_i="5"/>
       <fsummary>Information about I/O.</fsummary>
       <desc>
         <p>Returns <c><anno>Input</anno></c>,
@@ -5732,7 +5870,147 @@ true</pre>
     </func>
 
     <func>
-      <name name="statistics" arity="1" clause_i="5"/>
+      <name name="statistics" arity="1" clause_i="6"/>
+      <fsummary>Information about microstate accounting.</fsummary>
+      <desc>
+        <marker id="statistics_microstate_accounting"></marker>
+        <p>
+          Microstate accounting can be used to measure how much time the Erlang
+          runtime system spends doing various tasks. It is designed to be as
+          lightweight as possible, but there will be some overhead when this
+          is enabled. Microstate accounting is meant to be a profiling tool
+          to help figure out performance bottlenecks.
+          To <c>start</c>/<c>stop</c>/<c>reset</c> microstate_accounting you use
+          the system_flag
+          <seealso marker="#system_flag_microstate_accounting">
+            <c>microstate_accounting</c></seealso>.
+        </p>
+        <p>
+          <c>erlang:statistics(microstate_accounting)</c> returns a list of maps
+          representing some of the OS threads within ERTS. Each map contains
+          <c>type</c> and <c>id</c> fields that can be used to identify what
+          thread it is, and also a counters field that contains data about how
+          much time has been spent in the various states.</p>
+        <pre>
+> <input>erlang:statistics(microstate_accounting).</input>
+[#{counters => #{aux => 1899182914,
+                 check_io => 2605863602,
+                 emulator => 45731880463,
+                 gc => 1512206910,
+                 other => 5421338456,
+                 port => 221631,
+                 sleep => 5150294100},
+   id => 1,
+   type => scheduler}|...]
+        </pre>
+        <p>The time unit is the same as returned by
+        <seealso marker="kernel:os#perf_counter/0">
+          <c>os:perf_counter/0</c></seealso>.
+        So to convert it to milliseconds you could do something like this:</p>
+        <pre>
+lists:map(
+  fun(#{ counters := Cnt } = M) ->
+          MsCnt = maps:map(fun(_K, PerfCount) ->
+                                   erlang:convert_time_unit(PerfCount, perf_counter, 1000)
+                           end, Cnt),
+         M#{ counters := MsCnt }
+  end, erlang:statistics(microstate_accounting)).
+        </pre>
+        <p>
+          It is important to note that these values are not guaranteed to be
+          the exact time spent in each state. This is because of various
+          optimisation done in order to keep the overhead as small as possible.
+        </p>
+
+        <p>Currently the following <c><anno>MSAcc_Thread_Type</anno></c> are available:</p>
+        <taglist>
+          <tag><c>scheduler</c></tag>
+          <item>The main execution threads that do most of the work.</item>
+          <tag><c>async</c></tag><item>Async threads are used by various
+          linked-in drivers (mainly the file drivers) do offload non-cpu
+          intensive work.</item>
+          <tag><c>aux</c></tag><item>Takes care of any work that is not
+          specifically assigned to a scheduler.</item>
+        </taglist>
+        <p>Currently the following <c><anno>MSAcc_Thread_State</anno></c>s are available.
+        All states are exclusive, meaning that a thread cannot be in two states
+        at once. So if you add the numbers of all counters in a thread
+        you will get the total run-time for that thread.</p>
+        <taglist>
+          <tag><c>aux</c></tag>
+          <item>Time spent handling auxiliary jobs.</item>
+          <tag><c>check_io</c></tag>
+          <item>Time spent checking for new I/O events.</item>
+          <tag><c>emulator</c></tag>
+          <item>Time spent executing erlang processes.</item>
+          <tag><c>gc</c></tag>
+          <item>Time spent doing garbage collection. When extra states are
+          enabled this is the time spent doing non-fullsweep garbage
+          collections.</item>
+          <tag><c>other</c></tag>
+          <item>Time spent doing unaccounted things.</item>
+          <tag><c>port</c></tag>
+          <item>Time spent executing ports.</item>
+          <tag><c>sleep</c></tag>
+          <item>Time spent sleeping.</item>
+        </taglist>
+        <p>It is possible to add more fine grained <c><anno>MSAcc_Thread_State</anno></c>s
+        through configure.
+        (e.g. <c>./configure --with-microstate-accounting=extra</c>).
+        Enabling these states will cause a performance degradation when
+        microstate accounting is turned off and increase the overhead when
+        it is turned on.</p>
+        <taglist>
+          <tag><c>alloc</c></tag>
+          <item>Time spent managing memory. Without extra states this time is
+          spread out over all other states.</item>
+          <tag><c>bif</c></tag>
+          <item>Time spent in bifs. Without extra states this time is part of
+          the <c>emulator</c> state.</item>
+          <tag><c>busy_wait</c></tag>
+          <item>Time spent busy waiting. This is also the state where a
+          scheduler no longer reports that it is active when using
+          <seealso marker="#statistics_scheduler_wall_time">
+            <c>erlang:statistics(scheduler_wall_time)</c></seealso>.
+          So if you add all other states but this and sleep and then divide that
+          by all time in the thread you should get something very similar to the
+          scheduler_wall_time fraction. Without extra states this time is part
+          of the <c>other</c> state.</item>
+          <tag><c>ets</c></tag>
+          <item>Time spent executing ETS bifs. Without extra states this time is
+          part of the <c>emulator</c> state.</item>
+          <tag><c>gc_full</c></tag>
+          <item>Time spent doing fullsweep garbage collection. Without extra
+          states this time is part of the <c>gc</c> state.</item>
+          <tag><c>nif</c></tag>
+          <item>Time spent in nifs. Without extra states this time is part of
+          the <c>emulator</c> state.</item>
+          <tag><c>send</c></tag>
+          <item>Time spent sending messages (processes only). Without extra
+          states this time is part of the <c>emulator</c> state.</item>
+          <tag><c>timers</c></tag>
+          <item>Time spent managing timers. Without extra states this time is
+          part of the <c>other</c> state.</item>
+        </taglist>
+        <p>There is a utility module called
+        <seealso marker="runtime_tools:msacc"><c>msacc</c></seealso> in
+        runtime_tools that can be used to more easily analyse these
+        statistics.</p>
+
+        <p>
+          Returns <c>undefined</c> if the system flag
+          <seealso marker="#system_flag_microstate_accounting">
+            <c>microstate_accounting</c></seealso>
+          is turned off.
+	</p>
+        <p>The list of thread information is unsorted and may appear in
+        different order between calls.</p>
+        <note><p>The threads and states are subject to change without any
+        prior notice.</p></note>
+      </desc>
+    </func>
+    <func>
+      <name name="statistics" arity="1" clause_i="7"/>
       <fsummary>Information about reductions.</fsummary>
       <desc>
         <marker id="statistics_reductions"></marker>
@@ -5750,16 +6028,43 @@ true</pre>
     </func>
 
     <func>
-      <name name="statistics" arity="1" clause_i="6"/>
-      <fsummary>Information about the run-queue.</fsummary>
-      <desc>
-        <p>Returns the total length of run-queues, that is, the number
-          of processes that are ready to run on all available run-queues.</p>
+      <name name="statistics" arity="1" clause_i="8"/>
+      <fsummary>Information about the run-queues.</fsummary>
+      <desc><marker id="statistics_run_queue"></marker>
+        <p>
+	  Returns the total length of the run-queues. That is, the number
+          of processes and ports that are ready to run on all available
+	  run-queues. The information is gathered atomically. That
+	  is, the result is a consistent snapshot of the state, but
+	  this operation is much more expensive compared to
+	  <seealso marker="#statistics_total_run_queue_lengths"><c>statistics(total_run_queue_lengths)</c></seealso>.
+	  This especially when a large amount of schedulers is used.
+	</p>
       </desc>
     </func>
 
     <func>
-      <name name="statistics" arity="1" clause_i="7"/>
+      <name name="statistics" arity="1" clause_i="9"/>
+      <fsummary>Information about the run-queue lengths.</fsummary>
+      <desc><marker id="statistics_run_queue_lengths"></marker>
+	<p>
+	  Returns a list where each element represents the amount
+	  of processes and ports ready to run for each run queue. The
+	  element location in the list corresponds to the run queue
+	  of a scheduler. The first element corresponds to the run
+	  queue of scheduler number 1 and so on. The information is
+	  <em>not</em> gathered atomically. That is, the result is
+	  not necessarily a consistent snapshot of the state, but
+	  instead quite efficiently gathered. See also,
+	  <seealso marker="#statistics_total_run_queue_lengths"><c>statistics(total_run_queue_lengths)</c></seealso>,
+	  <seealso marker="#statistics_active_tasks"><c>statistics(active_tasks)</c></seealso>, and
+	  <seealso marker="#statistics_total_active_tasks"><c>statistics(total_active_tasks)</c></seealso>.
+	</p>
+      </desc>
+    </func>
+
+    <func>
+      <name name="statistics" arity="1" clause_i="10"/>
       <fsummary>Information about runtime.</fsummary>
       <desc>
         <p>Returns information about runtime, in milliseconds.</p>
@@ -5774,7 +6079,7 @@ true</pre>
     </func>
 
     <func>
-      <name name="statistics" arity="1" clause_i="8"/>
+      <name name="statistics" arity="1" clause_i="11"/>
       <fsummary>Information about each schedulers work time.</fsummary>
       <desc>
       <marker id="statistics_scheduler_wall_time"></marker>
@@ -5845,7 +6150,44 @@ ok
     </func>
 
     <func>
-      <name name="statistics" arity="1" clause_i="9"/>
+      <name name="statistics" arity="1" clause_i="12"/>
+      <fsummary>Information about active processes and ports.</fsummary>
+      <desc><marker id="statistics_total_active_tasks"></marker>
+	<p>
+	  Returns the total amount of active processes and ports in
+	  the system. That is, the number of processes and ports that
+	  are ready to run, or are currently running. The information
+	  is <em>not</em> gathered atomically. That is, the result
+	  is not necessarily a consistent snapshot of the state, but
+	  instead quite efficiently gathered. See also,
+	  <seealso marker="#statistics_active_tasks"><c>statistics(active_tasks)</c></seealso>,
+	  <seealso marker="#statistics_run_queue_lengths"><c>statistics(run_queue_lengths)</c></seealso>, and
+	  <seealso marker="#statistics_total_run_queue_lengths"><c>statistics(total_run_queue_lengths)</c></seealso>.
+	</p>
+      </desc>
+    </func>
+
+    <func>
+      <name name="statistics" arity="1" clause_i="13"/>
+      <fsummary>Information about the run-queue lengths.</fsummary>
+      <desc><marker id="statistics_total_run_queue_lengths"></marker>
+        <p>
+	  Returns the total length of the run-queues. That is, the number
+          of processes and ports that are ready to run on all available
+	  run-queues. The information is <em>not</em> gathered atomically.
+	  That is, the result is not necessarily a consistent snapshot of
+	  the state, but much more efficiently gathered compared to
+	  <seealso marker="#statistics_run_queue"><c>statistics(run_queue)</c></seealso>.
+	  See also,
+	  <seealso marker="#statistics_run_queue_lengths"><c>statistics(run_queue_lengths)</c></seealso>,
+	  <seealso marker="#statistics_total_active_tasks"><c>statistics(total_active_tasks)</c></seealso>, and
+	  <seealso marker="#statistics_active_tasks"><c>statistics(active_tasks)</c></seealso>.
+	</p>
+      </desc>
+    </func>
+
+    <func>
+      <name name="statistics" arity="1" clause_i="14"/>
       <fsummary>Information about wall clock.</fsummary>
       <desc>
         <p>Returns information about wall clock. <c>wall_clock</c> can
@@ -6079,6 +6421,17 @@ ok
 
     <func>
       <name name="system_flag" arity="2" clause_i="5"/>
+      <fsummary>Set system flag microstate_accounting</fsummary>
+      <desc><p><marker id="system_flag_microstate_accounting"></marker>
+      Turns on/off microstate accounting measurements. By passing reset it is possible to reset
+      all counters to 0.</p>
+      <p>For more information see,
+      <seealso marker="#statistics_microstate_accounting">erlang:statistics(microstate_accounting)</seealso>.
+      </p>
+      </desc>
+    </func>
+    <func>
+      <name name="system_flag" arity="2" clause_i="6"/>
       <fsummary>Sets system flag <c>min_heap_size</c>.</fsummary>
       <desc>
         <p>Sets the default minimum heap size for processes. The size
@@ -6093,7 +6446,7 @@ ok
     </func>
 
     <func>
-      <name name="system_flag" arity="2" clause_i="6"/>
+      <name name="system_flag" arity="2" clause_i="7"/>
       <fsummary>Sets system flag <c>min_bin_vheap_size</c>.</fsummary>
       <desc>
         <p>Sets the default minimum binary virtual heap size for
@@ -6110,7 +6463,7 @@ ok
     </func>
 
     <func>
-      <name name="system_flag" arity="2" clause_i="7"/>
+      <name name="system_flag" arity="2" clause_i="8"/>
       <fsummary>Sets system flag <c>multi_scheduling</c>.</fsummary>
       <desc>
         <p><marker id="system_flag_multi_scheduling"></marker>
@@ -6148,7 +6501,7 @@ ok
     </func>
 
     <func>
-      <name name="system_flag" arity="2" clause_i="8"/>
+      <name name="system_flag" arity="2" clause_i="9"/>
       <fsummary>Sets system flag <c>scheduler_bind_type</c>.</fsummary>
       <type name="scheduler_bind_type"/>
       <desc>
@@ -6266,7 +6619,7 @@ ok
     </func>
 
     <func>
-      <name name="system_flag" arity="2" clause_i="9"/>
+      <name name="system_flag" arity="2" clause_i="10"/>
       <fsummary>Sets system flag <c>scheduler_wall_time</c>.</fsummary>
       <desc><p><marker id="system_flag_scheduler_wall_time"></marker>
       Turns on or off scheduler wall time measurements.</p>
@@ -6276,7 +6629,7 @@ ok
     </func>
 
     <func>
-      <name name="system_flag" arity="2" clause_i="10"/>
+      <name name="system_flag" arity="2" clause_i="11"/>
       <fsummary>Sets system flag <c>schedulers_online</c>.</fsummary>
       <desc>
         <p><marker id="system_flag_schedulers_online"></marker>
@@ -6301,7 +6654,7 @@ ok
     </func>
 
     <func>
-      <name name="system_flag" arity="2" clause_i="11"/>
+      <name name="system_flag" arity="2" clause_i="12"/>
       <fsummary>Sets system flag <c>trace_control_word</c>.</fsummary>
       <desc>
         <p>Sets the value of the node trace control word to
@@ -6640,6 +6993,7 @@ ok
       <name name="system_info" arity="1" clause_i="65"/>
       <name name="system_info" arity="1" clause_i="66"/>
       <name name="system_info" arity="1" clause_i="67"/>
+      <name name="system_info" arity="1" clause_i="68"/>
       <fsummary>Information about the system.</fsummary>
       <desc>
         <p>Returns various information about the current system
@@ -7045,7 +7399,17 @@ ok
               used by the runtime system. It is on the form
 	      "&lt;major ver&gt;.&lt;minor ver&gt;".</p>
           </item>
-          <tag><c>otp_release</c></tag>
+          <tag><marker id="system_info_message_queue_data"><c>message_queue_data</c></marker></tag>
+          <item>
+            <p>Returns the default value of the <c>message_queue_data</c>
+	    process flag which is either <c>off_heap</c>, <c>on_heap</c>, or <c>mixed</c>.
+	    This default is set by the <c>erl</c> command line argument
+	    <seealso marker="erl#+xmqd"><c>+xmqd</c></seealso>. For more information on the
+	    <c>message_queue_data</c> process flag, see documentation of
+            <seealso marker="#process_flag_message_queue_data"><c>process_flag(message_queue_data,
+	    MQD)</c></seealso>.</p>
+          </item>
+          <tag><marker id="system_info_otp_release"><c>otp_release</c></marker></tag>
           <item>
           <marker id="system_info_otp_release"></marker>
             <p>Returns a string containing the OTP release number of the
@@ -7653,6 +8017,14 @@ ok
              <c>inactive</c>, and later <c>active</c> when the port
 	     callback returns.</p>
           </item>
+          <tag><c>monotonic_timestamp</c></tag>
+          <item>
+            <p>Timestamps in profile messages will use
+	    <seealso marker="time_correction#Erlang_Monotonic_Time">Erlang
+	    monotonic time</seealso>. The time-stamp (Ts) has the same
+	    format and value as produced by
+	    <c>erlang:monotonic_time(nano_seconds)</c>.</p>
+          </item>
           <tag><c>runnable_procs</c></tag>
           <item>
           <p>If a process is put into or removed from the run queue, a
@@ -7673,6 +8045,25 @@ ok
              <c>{profile, scheduler, Id, State, NoScheds, Ts}</c>, is
              sent to <c><anno>ProfilerPid</anno></c>.</p>
           </item>
+          <tag><c>strict_monotonic_timestamp</c></tag>
+          <item>
+            <p>Timestamps in profile messages will consisting of
+	    <seealso marker="time_correction#Erlang_Monotonic_Time">Erlang
+	    monotonic time</seealso> and a monotonically increasing
+	    integer. The time-stamp (Ts) has the same format and value
+	    as produced by <c>{erlang:monotonic_time(nano_seconds),
+	    erlang:unique_integer([monotonic])}</c>.</p>
+          </item>
+          <tag><c>timestamp</c></tag>
+          <item>
+            <p>Timestamps in profile messages will include a
+            time-stamp (Ts) that has the same form as returned by
+            <c>erlang:now()</c>. This is also the default if no
+	    timestamp flag is given. If <c>cpu_timestamp</c> has
+	    been enabled via <c>erlang:trace/3</c>, this will also
+	    effect the timestamp produced in profiling messages
+	    when <c>timestamp</c> flag is enabled.</p>
+          </item>
         </taglist>
         <note><p><c>erlang:system_profile</c> is considered experimental
           and its behavior can change in a future release.</p>
@@ -8032,7 +8423,10 @@ timestamp() ->
           <tag><c>cpu_timestamp</c></tag>
           <item>
             <p>A global trace flag for the Erlang node that makes all
-              trace time-stamps to be in CPU time, not wall clock time.
+              trace time-stamps using the <c>timestamp</c> flag to be
+	      in CPU time, not wall clock time. That is, <c>cpu_timestamp</c>
+	      will not be used if <c>monotonic_timestamp</c>, or
+	      <c>strict_monotonic_timestamp</c> is enabled.
               Only allowed with <c>PidSpec==all</c>. If the host
               machine OS does not support high-resolution
               CPU time measurements, <c>trace/3</c> exits with
@@ -8040,6 +8434,26 @@ timestamp() ->
               not synchronize this value across cores, so be prepared
               that time might seem to go backwards when using this option.</p>
           </item>
+          <tag><c>monotonic_timestamp</c></tag>
+          <item>
+            <p>Includes an
+	    <seealso marker="time_correction#Erlang_Monotonic_Time">Erlang
+	    monotonic time</seealso> time-stamp in all trace messages. The
+            time-stamp (Ts) has the same format and value as produced by
+            <c>erlang:monotonic_time(nano_seconds)</c>. This flag overrides
+	    the <c>cpu_timestamp</c> flag.</p>
+          </item>
+          <tag><c>strict_monotonic_timestamp</c></tag>
+          <item>
+            <p>Includes an timestamp consisting of
+	    <seealso marker="time_correction#Erlang_Monotonic_Time">Erlang
+	    monotonic time</seealso> and a monotonically increasing
+	    integer in all trace messages. The time-stamp (Ts) has the
+	    same format and value as produced by
+            <c>{erlang:monotonic_time(nano_seconds),
+	    erlang:unique_integer([monotonic])}</c>. This flag overrides
+	    the <c>cpu_timestamp</c> flag.</p>
+          </item>
           <tag><c>arity</c></tag>
           <item>
             <p>Used with the <c>call</c> trace flag.
@@ -8086,9 +8500,16 @@ timestamp() ->
 	in the following list. <c>Pid</c> is the process identifier of the
 	traced process in which the traced event has occurred. The
 	third tuple element is the message tag.</p>
-        <p>If flag <c>timestamp</c> is given, the first tuple
-          element is <c>trace_ts</c> instead, and the time-stamp
-          is added last in the message tuple.</p>
+        <p>If flag <c>timestamp</c>, <c>strict_monotonic_timestamp</c>, or
+	<c>monotonic_timestamp</c> is given, the first tuple
+        element is <c>trace_ts</c> instead, and the time-stamp
+        is added as an extra element last in the message tuple. If
+	multiple timestamp flags are passed, <c>timestamp</c> has
+	precedence over <c>strict_monotonic_timestamp</c> which
+	in turn has precedence over <c>monotonic_timestamp</c>. All
+	timestamp flags are remembered, so if two are passed
+	and the one with highest precedence later is disabled
+	the other one will become active.</p>
         <marker id="trace_3_trace_messages"></marker>
         <taglist>
           <tag><c>{trace, Pid, 'receive', Msg}</c></tag>
@@ -8183,14 +8604,14 @@ timestamp() ->
             <p>When <c>Pid</c> is scheduled to run. The process
               runs in function <c>{M, F, Arity}</c>. On some rare
               occasions, the current function cannot be determined,
-              then the last element <c>Arity</c> is <c>0</c>.</p>
+              then the last element is <c>0</c>.</p>
           </item>
           <tag><c>{trace, Pid, out, {M, F, Arity} | 0}</c></tag>
           <item>
             <p>When <c>Pid</c> is scheduled out. The process was
               running in function {M, F, Arity}. On some rare occasions,
               the current function cannot be determined, then the last
-              element <c>Arity</c> is <c>0</c>.</p>
+              element is <c>0</c>.</p>
           </item>
           <tag><c>{trace, Pid, gc_start, Info}</c></tag>
           <item>