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Diffstat (limited to 'erts/doc/src/erl.xml')
| -rw-r--r-- | erts/doc/src/erl.xml | 50 |
1 files changed, 39 insertions, 11 deletions
diff --git a/erts/doc/src/erl.xml b/erts/doc/src/erl.xml index c151b35d77..dfd16c3d19 100644 --- a/erts/doc/src/erl.xml +++ b/erts/doc/src/erl.xml @@ -748,19 +748,47 @@ </item> <tag><marker id="+S"><c><![CDATA[+S Schedulers:SchedulerOnline]]></c></marker></tag> <item> - <p>Sets the amount of scheduler threads to create and scheduler - threads to set online when SMP support has been enabled. - Valid range for both values are 1-1024. If the - Erlang runtime system is able to determine the amount - of logical processors configured and logical processors available, - <c>Schedulers</c> will default to logical processors configured, - and <c>SchedulersOnline</c> will default to logical processors - available; otherwise, the default values will be 1. <c>Schedulers</c> - may be omitted if <c>:SchedulerOnline</c> is not and vice versa. The - amount of schedulers online can be changed at run time via + <p>Sets the number of scheduler threads to create and scheduler + threads to set online when SMP support has been enabled. The maximum for + both values is 1024. If the Erlang runtime system is able to determine the + amount of logical processors configured and logical processors available, + <c>Schedulers</c> will default to logical processors configured, and + <c>SchedulersOnline</c> will default to logical processors available; + otherwise, the default values will be 1. <c>Schedulers</c> may be omitted + if <c>:SchedulerOnline</c> is not and vice versa. The number of schedulers + online can be changed at run time via <seealso marker="erlang#system_flag_schedulers_online">erlang:system_flag(schedulers_online, SchedulersOnline)</seealso>. </p> - <p>This flag will be ignored if the emulator doesn't have + <p>If <c>Schedulers</c> or <c>SchedulersOnline</c> is specified as a + negative number, the value is subtracted from the default number of + logical processors configured or logical processors available, respectively. + </p> + <p>Specifying the value 0 for <c>Schedulers</c> or <c>SchedulersOnline</c> + resets the number of scheduler threads or scheduler threads online respectively + to its default value. + </p> + <p>This option is ignored if the emulator doesn't have + SMP support enabled (see the <seealso marker="#smp">-smp</seealso> + flag).</p> + </item> + <tag><marker id="+SP"><c><![CDATA[+SP SchedulersPercentage:SchedulersOnlinePercentage]]></c></marker></tag> + <item> + <p>Similar to <seealso marker="#+S">+S</seealso> but uses percentages to set the + number of scheduler threads to create, based on logical processors configured, + and scheduler threads to set online, based on logical processors available, when + SMP support has been enabled. Specified values must be greater than 0. For example, + <c>+SP 50:25</c> sets the number of scheduler threads to 50% of the logical processors + configured and the number of scheduler threads online to 25% of the logical processors available. + <c>SchedulersPercentage</c> may be omitted if <c>:SchedulersOnlinePercentage</c> is + not and vice versa. The number of schedulers online can be changed at run time via + <seealso marker="erlang#system_flag_schedulers_online">erlang:system_flag(schedulers_online, SchedulersOnline)</seealso>. + </p> + <p>This option interacts with <seealso marker="#+S">+S</seealso> settings. + For example, on a system with 8 logical cores configured and 8 logical cores + available, the combination of the options <c>+S 4:4 +SP 50:25</c> (in either order) + results in 2 scheduler threads (50% of 4) and 1 scheduler thread online (25% of 4). + </p> + <p>This option is ignored if the emulator doesn't have SMP support enabled (see the <seealso marker="#smp">-smp</seealso> flag).</p> </item> |