Deprecate erlang:system_flag/2 arguments scheduler_bind_type and cpu_topology

The use of erlang:system_flag(scheduler_bind_type, _) and
erlang:system_flag(cpu_topology, _) have been deprecated and scheduled
for removal in erts-5.10/OTP-R16. For more information see the
documentation of erlang:system_flag/2.

3 files changed, 159 insertions, 108 deletions

diff --git a/erts/doc/src/erl.xml b/erts/doc/src/erl.xml
index 048ffbcd47..501b8eb176 100644
--- a/erts/doc/src/erl.xml
+++ b/erts/doc/src/erl.xml
@@ -658,41 +658,66 @@
 	    </p>
 	    <taglist>
 	      <tag><c>u</c></tag>
-	      <item><p>Same as
-	      <seealso marker="erlang#system_flag_scheduler_bind_type">erlang:system_flag(scheduler_bind_type, unbound)</seealso>.
-	      </p></item>
+              <item>
+                <p><c>unbound</c> - Schedulers will not be bound to logical
+		processors, i.e., the operating system decides where the
+		scheduler threads execute, and when to migrate them. This is
+		the default.</p>
+              </item>
 	      <tag><c>ns</c></tag>
-	      <item><p>Same as
-	      <seealso marker="erlang#system_flag_scheduler_bind_type">erlang:system_flag(scheduler_bind_type, no_spread)</seealso>.
-	      </p></item>
+              <item>
+                <p><c>no_spread</c> - Schedulers with close scheduler
+		identifiers will be bound as close as possible in hardware.</p>
+              </item>
 	      <tag><c>ts</c></tag>
-	      <item><p>Same as
-	      <seealso marker="erlang#system_flag_scheduler_bind_type">erlang:system_flag(scheduler_bind_type, thread_spread)</seealso>.
-	      </p></item>
+              <item>
+                <p><c>thread_spread</c> - Thread refers to hardware threads
+		(e.g. Intels hyper-threads). Schedulers with low scheduler
+		identifiers, will be bound to the first hardware thread of
+		each core, then schedulers with higher scheduler identifiers
+		will be bound to the second hardware thread of each core,
+		etc.</p>
+              </item>
 	      <tag><c>ps</c></tag>
-	      <item><p>Same as
-	      <seealso marker="erlang#system_flag_scheduler_bind_type">erlang:system_flag(scheduler_bind_type, processor_spread)</seealso>.
-	      </p></item>
+              <item>
+                <p><c>processor_spread</c> - Schedulers will be spread like
+		<c>thread_spread</c>, but also over physical processor chips.</p>
+              </item>
 	      <tag><c>s</c></tag>
-	      <item><p>Same as
-	      <seealso marker="erlang#system_flag_scheduler_bind_type">erlang:system_flag(scheduler_bind_type, spread)</seealso>.
-	      </p></item>
+              <item>
+                <p><c>spread</c> - Schedulers will be spread as much as
+		possible.</p>
+              </item>
 	      <tag><c>nnts</c></tag>
-	      <item><p>Same as
-	      <seealso marker="erlang#system_flag_scheduler_bind_type">erlang:system_flag(scheduler_bind_type, no_node_thread_spread)</seealso>.
-	      </p></item>
+              <item>
+                <p><c>no_node_thread_spread</c> - Like <c>thread_spread</c>,
+		but if multiple NUMA (Non-Uniform Memory Access) nodes exists,
+		schedulers will be spread over one NUMA node at a time,
+		i.e., all logical processors of one NUMA node will be bound
+		to schedulers in sequence.</p>
+              </item>
 	      <tag><c>nnps</c></tag>
-	      <item><p>Same as
-	      <seealso marker="erlang#system_flag_scheduler_bind_type">erlang:system_flag(scheduler_bind_type, no_node_processor_spread)</seealso>.
-	      </p></item>
+              <item>
+                <p><c>no_node_processor_spread</c> - Like
+		<c>processor_spread</c>, but if multiple NUMA nodes exists,
+		schedulers will be spread over one NUMA node at a time, i.e.,
+		all logical processors of one NUMA node will be bound to
+		schedulers in sequence.</p>
+              </item>
 	      <tag><c>tnnps</c></tag>
-	      <item><p>Same as
-	      <seealso marker="erlang#system_flag_scheduler_bind_type">erlang:system_flag(scheduler_bind_type, thread_no_node_processor_spread)</seealso>.
-	      </p></item>
+              <item>
+                <p><c>thread_no_node_processor_spread</c> - A combination of
+		<c>thread_spread</c>, and <c>no_node_processor_spread</c>.
+		Schedulers will be spread over hardware threads across NUMA
+		nodes, but schedulers will only be spread over processors
+		internally in one NUMA node at a time.</p>
+              </item>
 	      <tag><c>db</c></tag>
-	      <item><p>Same as
-	      <seealso marker="erlang#system_flag_scheduler_bind_type">erlang:system_flag(scheduler_bind_type, default_bind)</seealso>.
-	      </p></item>
+              <item>
+                <p><c>default_bind</c> - Binds schedulers the default way.
+		Currently the default is <c>thread_no_node_processor_spread</c>
+		(which might change in the future).</p>
+              </item>
 	    </taglist>
 	    <p>Binding of schedulers is currently only supported on newer
 	       Linux, Solaris, FreeBSD, and Windows systems.</p>
@@ -716,8 +741,22 @@
 	       instead. In some cases this performance penalty might be
 	       severe. If this is the case, you are advised to not
 	       bind the schedulers.</p>
-	    <p>For more information, see
-	    <seealso marker="erlang#system_flag_scheduler_bind_type">erlang:system_flag(scheduler_bind_type, SchedulerBindType)</seealso>.
+            <p>How schedulers are bound matters. For example, in
+	       situations when there are fewer running processes than
+	       schedulers online, the runtime system tries to migrate
+	       processes to schedulers with low scheduler identifiers.
+	       The more the schedulers are spread over the hardware,
+	       the more resources will be available to the runtime
+	       system in such situations.
+	    </p>
+	    <p>
+	       <em>NOTE:</em> If a scheduler fails to bind, this
+	       will often be silently ignored. This since it isn't always
+	       possible to verify valid logical processor identifiers. If
+	       an error is reported, it will be reported to the
+	       <c>error_logger</c>. If you want to verify that the
+	       schedulers actually have bound as requested, call
+	       <seealso marker="erlang#system_info_scheduler_bindings">erlang:system_info(scheduler_bindings)</seealso>.
 	    </p>
           </item>
           <tag><marker id="+sct"><c>+sct CpuTopology</c></marker></tag>
@@ -735,6 +774,12 @@
               <item><c><![CDATA[<IdDefs> = <LogicalIds><ThreadIds><CoreIds><ProcessorIds><NodeIds> | <LogicalIds><ThreadIds><CoreIds><NodeIds><ProcessorIds>]]></c></item>
               <item><c><![CDATA[CpuTopology = <IdDefs>:<IdDefs> | <IdDefs>]]></c></item>
             </list>
+            <p>Set a user defined CPU topolgy. The user defined
+	       CPU topology will override any automatically detected
+	       CPU topology. The CPU topology is used when
+	       <seealso marker="#+sbt">binding schedulers to logical
+	       processors</seealso>.
+	    </p>
             <p>Upper-case letters signify real identifiers and lower-case
 	       letters signify fake identifiers only used for description
 	       of the topology. Identifiers passed as real identifiers may
@@ -834,7 +879,7 @@
 	        how the real CPU topology looks like is likely to
 		decrease the performance of the runtime system.</p>
 	    <p>For more information, see
-	    <seealso marker="erlang#system_flag_cpu_topology">erlang:system_flag(cpu_topology, CpuTopology)</seealso>.</p>
+	    <seealso marker="erlang#system_info_cpu_topology">erlang:system_info(cpu_topology)</seealso>.</p>
           </item>
 	  <tag><marker id="+swt"><c>+swt very_low|low|medium|high|very_high</c></marker></tag>
 	  <item>
diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml
index ae6300a728..e28435cd29 100644
--- a/erts/doc/src/erlang.xml
+++ b/erts/doc/src/erlang.xml
@@ -5042,6 +5042,14 @@ true</pre>
         <v>Flag, Value, OldValue -- see below</v>
       </type>
       <desc>
+        <warning>
+          <p>The
+	  <seealso marker="#system_flag_cpu_topology">cpu_topology</seealso>,
+	  and
+	  <seealso marker="#system_flag_scheduler_bind_type">scheduler_bind_type</seealso>
+	  <c>Flag</c>s are <em>deprecated</em> and have been scheduled for
+	  removal in erts-5.10/OTP-R16.</p>
+        </warning>
         <p>Sets various system properties of the Erlang node. Returns
           the old value of the flag.</p>
         <taglist>
@@ -5052,6 +5060,12 @@ true</pre>
           </item>
           <tag><marker id="system_flag_cpu_topology"><c>erlang:system_flag(cpu_topology, CpuTopology)</c></marker></tag>
           <item>
+	    <p><em>NOTE:</em> This argument is <em>deprecated</em> and
+	    scheduled for removal in erts-5.10/OTP-R16. Instead of using
+	    this argument you are advised to use the <c>erl</c> command
+	    line argument <seealso marker="erts:erl#+sct">+sct</seealso>.
+	    When this argument has been removed a final CPU topology to use
+	    will be determined at emulator boot time.</p>
             <p>Sets the user defined <c>CpuTopology</c>. The user defined
 	       CPU topology will override any automatically detected
 	       CPU topology. By passing <c>undefined</c> as <c>CpuTopology</c>
@@ -5066,15 +5080,15 @@ true</pre>
 	       to rebind according to the new CPU topology.
 	    </p>
 	    <p>The user defined CPU topology can also be set by passing
-	       the <seealso marker="erl#+sct">+sct</seealso> command
+	       the <seealso marker="erts:erl#+sct">+sct</seealso> command
 	       line argument to <c>erl</c>.
 	    </p>
 	    <p>For information on the <c>CpuTopology</c> type
 	       and more, see the documentation of
 	       <seealso marker="#system_info_cpu_topology">erlang:system_info(cpu_topology)</seealso>,
-	       the <c>erl</c> <seealso marker="erl#+sct">+sct</seealso>
-	       emulator flag, and
-	       <seealso marker="#system_flag_scheduler_bind_type">erlang:system_flag(scheduler_bind_type, How)</seealso>.
+	       and the <c>erl</c> <seealso marker="erts:erl#+sct">+sct</seealso>
+	       and <seealso marker="erts:erl#+sbt">+sbt</seealso>
+	       command line flags.
 	    </p>
           </item>
           <tag><c>erlang:system_flag(fullsweep_after, Number)</c></tag>
@@ -5150,6 +5164,12 @@ true</pre>
           </item>
           <tag><marker id="system_flag_scheduler_bind_type"><c>erlang:system_flag(scheduler_bind_type, How)</c></marker></tag>
           <item>
+	    <p><em>NOTE:</em> This argument is <em>deprecated</em> and
+	    scheduled for removal in erts-5.10/OTP-R16. Instead of using
+	    this argument you are advised to use the <c>erl</c> command
+	    line argument <seealso marker="erts:erl#+sbt">+sbt</seealso>.
+	    When this argument has been removed a final scheduler bind type
+	    to use will be determined at emulator boot time.</p>
 	    <p>Controls if and how schedulers are bound to logical
 	       processors.</p>
 	    <p>When <c>erlang:system_flag(scheduler_bind_type, How)</c> is
@@ -5171,7 +5191,8 @@ true</pre>
 	       the CPU topology needs to be known. If the runtime system fails
 	       to automatically detect the CPU topology, it can be defined.
 	       For more information on how to define the CPU topology, see 
-	       <seealso marker="#system_flag_cpu_topology">erlang:system_flag(cpu_topology, CpuTopology)</seealso>.
+	       the <c>erl</c> <seealso marker="erts:erl#+sct">+sct</seealso> command
+	       line flag.
 	    </p>
             <p>The runtime system will by default <em>not</em> bind schedulers
 	       to logical processors.
@@ -5189,71 +5210,42 @@ true</pre>
 	       currently be one of:</p>
             <taglist>
               <tag><c>unbound</c></tag>
-              <item>
-                <p>Schedulers will not be bound to logical processors, i.e.,
-		   the operating system decides where the scheduler threads
-		   execute, and when to migrate them. This is the default.</p>
-              </item>
+              <item><p>Same as the <c>erl</c> command line argument
+	      <seealso marker="erts:erl#+sbt">+sbt u</seealso>.
+	      </p></item>
               <tag><c>no_spread</c></tag>
-              <item>
-                <p>Schedulers with close scheduler identifiers will be bound
-		   as close as possible in hardware.</p>
-              </item>
+              <item><p>Same as the <c>erl</c> command line argument
+	      <seealso marker="erts:erl#+sbt">+sbt ns</seealso>.
+	      </p></item>
               <tag><c>thread_spread</c></tag>
-              <item>
-                <p>Thread refers to hardware threads (e.g. Intels
-		   hyper-threads). Schedulers with low scheduler identifiers,
-		   will be bound to the first hardware thread of each core,
-		   then schedulers with higher scheduler identifiers will be
-		   bound to the second hardware thread of each core, etc.</p>
-              </item>
+              <item><p>Same as the <c>erl</c> command line argument
+	      <seealso marker="erts:erl#+sbt">+sbt ts</seealso>.
+	      </p></item>
               <tag><c>processor_spread</c></tag>
-              <item>
-                <p>Schedulers will be spread like <c>thread_spread</c>, but
-		   also over physical processor chips.</p>
-              </item>
+              <item><p>Same as the <c>erl</c> command line argument
+	      <seealso marker="erts:erl#+sbt">+sbt ps</seealso>.
+	      </p></item>
               <tag><c>spread</c></tag>
-              <item>
-                <p>Schedulers will be spread as much as possible.</p>
-              </item>
+              <item><p>Same as the <c>erl</c> command line argument
+	      <seealso marker="erts:erl#+sbt">+sbt s</seealso>.
+	      </p></item>
               <tag><c>no_node_thread_spread</c></tag>
-              <item>
-                <p>Like <c>thread_spread</c>, but if multiple NUMA
-		   (Non-Uniform Memory Access) nodes exists,
-		   schedulers will be spread over one NUMA node at a time,
-		   i.e., all logical processors of one NUMA node will
-		   be bound to schedulers in sequence.</p>
-              </item>
+              <item><p>Same as the <c>erl</c> command line argument
+	      <seealso marker="erts:erl#+sbt">+sbt nnts</seealso>.
+	      </p></item>
               <tag><c>no_node_processor_spread</c></tag>
-              <item>
-                <p>Like <c>processor_spread</c>, but if multiple NUMA
-		   nodes exists, schedulers will be spread over one
-		   NUMA node at a time, i.e., all logical processors of
-		   one NUMA node will be bound to schedulers in sequence.</p>
-              </item>
+              <item><p>Same as the <c>erl</c> command line argument
+	      <seealso marker="erts:erl#+sbt">+sbt nnps</seealso>.
+	      </p></item>
               <tag><c>thread_no_node_processor_spread</c></tag>
-              <item>
-                <p>A combination of <c>thread_spread</c>, and
-		<c>no_node_processor_spread</c>. Schedulers will be
-		spread over hardware threads across NUMA nodes, but
-		schedulers will only be spread over processors internally
-		in one NUMA node at a time.</p>
-              </item>
+              <item><p>Same as the <c>erl</c> command line argument
+	      <seealso marker="erts:erl#+sbt">+sbt tnnps</seealso>.
+	      </p></item>
               <tag><c>default_bind</c></tag>
-              <item>
-                <p>Binds schedulers the default way. Currently the default
-		is <c>thread_no_node_processor_spread</c> (which might change
-		in the future).</p>
-              </item>
+              <item><p>Same as the <c>erl</c> command line argument
+	      <seealso marker="erts:erl#+sbt">+sbt db</seealso>.
+	      </p></item>
 	    </taglist>
-            <p>How schedulers are bound matters. For example, in
-	       situations when there are fewer running processes than
-	       schedulers online, the runtime system tries to migrate
-	       processes to schedulers with low scheduler identifiers.
-	       The more the schedulers are spread over the hardware,
-	       the more resources will be available to the runtime
-	       system in such situations.
-	    </p>
 	    <p>The value returned equals <c>How</c> before the
 	       <c>scheduler_bind_type</c> flag was changed.</p>
 	    <p>Failure:</p>
@@ -5272,15 +5264,15 @@ true</pre>
               </item>
             </taglist>
 	    <p>The scheduler bind type can also be set by passing
-	       the <seealso marker="erl#+sbt">+sbt</seealso> command
+	       the <seealso marker="erts:erl#+sbt">+sbt</seealso> command
 	       line argument to <c>erl</c>.
 	    </p>
 	    <p>For more information, see
 	       <seealso marker="#system_info_scheduler_bind_type">erlang:system_info(scheduler_bind_type)</seealso>,
 	       <seealso marker="#system_info_scheduler_bindings">erlang:system_info(scheduler_bindings)</seealso>,
-	       the <c>erl</c> <seealso marker="erl#+sbt">+sbt</seealso>
-	       emulator flag, and
-	       <seealso marker="#system_flag_cpu_topology">erlang:system_flag(cpu_topology, CpuTopology)</seealso>.
+	       the <c>erl</c> <seealso marker="erts:erl#+sbt">+sbt</seealso>
+	       and <seealso marker="erts:erl#+sct">+sct</seealso> command line
+	       flags.
 	    </p>
           </item>
           <tag><marker id="system_flag_schedulers_online"><c>erlang:system_flag(schedulers_online, SchedulersOnline)</c></marker></tag>
@@ -5481,10 +5473,12 @@ true</pre>
           <item>
 	    <p>Returns the <c>CpuTopology</c> which currently is used by the
 	       emulator. The CPU topology is used when binding schedulers
-	       to logical processors. The CPU topology used is the user defined
-	       CPU topology if such exist; otherwise, the automatically
-	       detected CPU topology if such exist. If no CPU topology
-	       exist <c>undefined</c> is returned.</p>
+	       to logical processors. The CPU topology used is the
+	       <seealso marker="erlang#system_info_cpu_topology_defined">user
+	       defined CPU topology</seealso> if such exists; otherwise, the
+	       <seealso marker="erlang#system_info_cpu_topology_detected">automatically
+	       detected CPU topology</seealso> if such exists. If no CPU topology
+	       exists, <c>undefined</c> is returned.</p>
             <p>Types:</p>
             <list type="bulleted">
               <item><c>CpuTopology = LevelEntryList | undefined</c></item>
@@ -5531,8 +5525,8 @@ true</pre>
           <item>
             <p>Returns the user defined <c>CpuTopology</c>. For more
 	       information see the documentation of
-	       <seealso marker="#system_flag_cpu_topology">erlang:system_flag(cpu_topology, CpuTopology)</seealso>
-               and the documentation of the
+	       the <c>erl</c> <seealso marker="erts:erl#+sct">+sct</seealso> command
+	       line flag, and the documentation of the
 	       <seealso marker="#system_info_cpu_topology">cpu_topology</seealso>
 	       argument.
 	    </p>
@@ -5610,7 +5604,7 @@ true</pre>
           <item>
             <p>Returns the value of the distribution buffer busy limit
 	    in bytes. This limit can be set on startup by passing the
-	    <seealso marker="erl#+zdbbl">+zdbbl</seealso> command line
+	    <seealso marker="erts:erl#+zdbbl">+zdbbl</seealso> command line
 	    flag to <c>erl</c>.</p>
           </item>
           <tag><c>fullsweep_after</c></tag>
@@ -5812,14 +5806,13 @@ true</pre>
 	    <p>Returns information on how user has requested
 	       schedulers to be bound or not bound.</p>
 	    <p><em>NOTE:</em> Even though user has requested
-	       schedulers to be bound via
-	       <seealso marker="#system_flag_scheduler_bind_type">erlang:system_flag(scheduler_bind_type, How)</seealso>,
-	       they might have silently failed to bind. In order to
-	       inspect actual scheduler bindings call
+	       schedulers to be bound, they might have silently failed
+	       to bind. In order to inspect actual scheduler bindings call
 	       <seealso marker="#system_info_scheduler_bindings">erlang:system_info(scheduler_bindings)</seealso>.
 	    </p>
 	    <p>For more information, see
-	       <seealso marker="#system_flag_scheduler_bind_type">erlang:system_flag(scheduler_bind_type, How)</seealso>, and
+	       the <c>erl</c> <seealso marker="erts:erl#+sbt">+sbt</seealso>
+	       command line argument, and
 	       <seealso marker="#system_info_scheduler_bindings">erlang:system_info(scheduler_bindings)</seealso>.
 	    </p>
           </item>
@@ -5842,7 +5835,8 @@ true</pre>
 	    <p>Note that only schedulers online can be bound to logical
 	       processors.</p>
 	    <p>For more information, see
-	       <seealso marker="#system_flag_scheduler_bind_type">erlang:system_flag(scheduler_bind_type, How)</seealso>,
+	       the <c>erl</c> <seealso marker="erts:erl#+sbt">+sbt</seealso>
+	       command line argument,
 	       <seealso marker="#system_info_schedulers_online">erlang:system_info(schedulers_online)</seealso>.
 	    </p>
           </item>
diff --git a/erts/emulator/beam/bif.c b/erts/emulator/beam/bif.c
index 07fdd809f8..9459be4fdb 100644
--- a/erts/emulator/beam/bif.c
+++ b/erts/emulator/beam/bif.c
@@ -4044,8 +4044,20 @@ BIF_RETTYPE system_flag_2(BIF_ALIST_2)
 	if (is_value(res))
 	    BIF_RET(res);
     } else if (ERTS_IS_ATOM_STR("cpu_topology", BIF_ARG_1)) {
+	erts_send_warning_to_logger_str(
+	    BIF_P->group_leader,
+	    "A call to erlang:system_flag(cpu_topology, _) was made.\n"
+	    "The cpu_topology argument is deprecated and scheduled\n"
+	    "for removal in erts-5.10/OTP-R16. For more information\n"
+	    "see the erlang:system_flag/2 documentation.\n");
 	BIF_TRAP1(set_cpu_topology_trap, BIF_P, BIF_ARG_2);
     } else if (ERTS_IS_ATOM_STR("scheduler_bind_type", BIF_ARG_1)) {
+	erts_send_warning_to_logger_str(
+	    BIF_P->group_leader,
+	    "A call to erlang:system_flag(scheduler_bind_type, _) was\n"
+	    "made. The scheduler_bind_type argument is deprecated and\n"
+	    "scheduled for removal in erts-5.10/OTP-R16. For more\n"
+	    "information see the erlang:system_flag/2 documentation.\n");
 	return erts_bind_schedulers(BIF_P, BIF_ARG_2);
     }
     error: