From d4f67bb08dec687671929b389f172dc2988aa363 Mon Sep 17 00:00:00 2001 From: Rickard Green Date: Sat, 19 Nov 2011 01:46:54 +0100 Subject: 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. --- erts/doc/src/erl.xml | 105 ++++++++++++++++++++++++++++++++++++--------------- 1 file changed, 75 insertions(+), 30 deletions(-) (limited to 'erts/doc/src/erl.xml') 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 @@

u -

Same as - erlang:system_flag(scheduler_bind_type, unbound). -

+ +

unbound - 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.

+ ns -

Same as - erlang:system_flag(scheduler_bind_type, no_spread). -

+ +

no_spread - Schedulers with close scheduler + identifiers will be bound as close as possible in hardware.

+ ts -

Same as - erlang:system_flag(scheduler_bind_type, thread_spread). -

+ +

thread_spread - 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.

+ ps -

Same as - erlang:system_flag(scheduler_bind_type, processor_spread). -

+ +

processor_spread - Schedulers will be spread like + thread_spread, but also over physical processor chips.

+ s -

Same as - erlang:system_flag(scheduler_bind_type, spread). -

+ +

spread - Schedulers will be spread as much as + possible.

+ nnts -

Same as - erlang:system_flag(scheduler_bind_type, no_node_thread_spread). -

+ +

no_node_thread_spread - Like thread_spread, + 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.

+ nnps -

Same as - erlang:system_flag(scheduler_bind_type, no_node_processor_spread). -

+ +

no_node_processor_spread - Like + processor_spread, 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.

+ tnnps -

Same as - erlang:system_flag(scheduler_bind_type, thread_no_node_processor_spread). -

+ +

thread_no_node_processor_spread - A combination of + thread_spread, and no_node_processor_spread. + 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.

+ db -

Same as - erlang:system_flag(scheduler_bind_type, default_bind). -

+ +

default_bind - Binds schedulers the default way. + Currently the default is thread_no_node_processor_spread + (which might change in the future).

+

Binding of schedulers is currently only supported on newer Linux, Solaris, FreeBSD, and Windows systems.

@@ -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.

-

For more information, see - erlang:system_flag(scheduler_bind_type, SchedulerBindType). +

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. +

+

+ NOTE: 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 + error_logger. If you want to verify that the + schedulers actually have bound as requested, call + erlang:system_info(scheduler_bindings).

+sct CpuTopology @@ -735,6 +774,12 @@ = | ]]> : | ]]> +

Set a user defined CPU topolgy. The user defined + CPU topology will override any automatically detected + CPU topology. The CPU topology is used when + binding schedulers to logical + processors. +

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.

For more information, see - erlang:system_flag(cpu_topology, CpuTopology).

+ erlang:system_info(cpu_topology).

+swt very_low|low|medium|high|very_high -- cgit v1.2.3