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-rw-r--r--erts/doc/src/erl.xml36
-rw-r--r--erts/doc/src/erlang.xml19
2 files changed, 51 insertions, 4 deletions
diff --git a/erts/doc/src/erl.xml b/erts/doc/src/erl.xml
index bb741c7836..df80142ce1 100644
--- a/erts/doc/src/erl.xml
+++ b/erts/doc/src/erl.xml
@@ -41,6 +41,26 @@
to scroll back to text which has scrolled off the screen.
The <c><![CDATA[erl]]></c> program must be used, however, in pipelines or if
you want to redirect standard input or output.</p>
+ <note><p>As of ERTS version 5.8 (OTP-R14A) the runtime system will by
+ default bind schedulers to logical processors using the
+ <c>default_bind</c> bind type if the amount of schedulers are
+ at least equal to the amount of logical processors configured,
+ binding of schedulers is supported, and a CPU topology is
+ available at startup.
+ </p><p>
+ If the Erlang runtime system is the only operating system
+ process that binds threads to logical processors, this
+ improves the performance of the runtime system. However,
+ if other operating system processes (as for example
+ another Erlang runtime system) also bind threads to
+ logical processors, there might be a performance penalty
+ instead. If this is the case you, are are advised to
+ unbind the schedulers using the
+ <seealso marker="#+sbt">+sbtu</seealso> command line argument,
+ or by invoking
+ <seealso marker="erlang#system_flag_scheduler_bind_type">erlang:system_flag(scheduler_bind_type,
+ unbound)</seealso>.</p>
+ </note>
</description>
<funcs>
<func>
@@ -657,6 +677,22 @@
that the <c>+sct</c> flag may have to be passed before the
<c>+sbt</c> flag on the command line (in case no CPU topology
has been automatically detected).</p>
+ <p>The runtime system will by default bind schedulers to logical
+ processors using the <c>default_bind</c> bind type if the amount
+ of schedulers are at least equal to the amount of logical
+ processors configured, binding of schedulers is supported,
+ and a CPU topology is available at startup.
+ </p>
+ <p><em>NOTE:</em> If the Erlang runtime system is the only operating
+ system process that binds threads to logical processors, this
+ improves the performance of the runtime system. However, if other
+ operating system processes (as for example another Erlang runtime
+ system) also bind threads to logical processors, there might be a
+ performance penalty instead. If this is the case you, are advised
+ to unbind the schedulers using the <c>+sbtu</c> command line
+ argument, or by invoking
+ <seealso marker="erlang#system_flag_scheduler_bind_type">erlang:system_flag(scheduler_bind_type,
+ unbound)</seealso>.</p>
<p>For more information, see
<seealso marker="erlang#system_flag_scheduler_bind_type">erlang:system_flag(scheduler_bind_type, SchedulerBindType)</seealso>.
</p>
diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml
index c3c0dd77d7..c8fe7b4bd2 100644
--- a/erts/doc/src/erlang.xml
+++ b/erts/doc/src/erlang.xml
@@ -5156,10 +5156,21 @@ true</pre>
For more information on how to define the CPU topology, see
<seealso marker="#system_flag_cpu_topology">erlang:system_flag(cpu_topology, CpuTopology)</seealso>.
</p>
- <p><em>NOTE:</em> If other programs on the system have bound
- to processors, e.g. another Erlang runtime system, you
- may lose performance when binding schedulers. Therefore,
- schedulers are by default not bound.</p>
+ <p>The runtime system will by default bind schedulers to logical
+ processors using the <c>default_bind</c> bind type if the amount
+ of schedulers are at least equal to the amount of logical
+ processors configured, binding of schedulers is supported,
+ and a CPU topology is available at startup.
+ </p>
+ <p><em>NOTE:</em> If the Erlang runtime system is the only
+ operating system process that binds threads to logical processors,
+ this improves the performance of the runtime system. However,
+ if other operating system processes (as for example another Erlang
+ runtime system) also bind threads to logical processors, there
+ might be a performance penalty instead. If this is the case you,
+ are are advised to unbind the schedulers using the
+ <seealso marker="erl#+sbt">+sbtu</seealso> command line argument,
+ or <c>erlang:system_flag(scheduler_bind_type, unbound)</c>.</p>
<p>Schedulers can be bound in different ways. The <c>How</c>
argument determines how schedulers are bound. <c>How</c> can
currently be one of:</p>