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-rw-r--r--erts/doc/src/erl.xml19
1 files changed, 18 insertions, 1 deletions
diff --git a/erts/doc/src/erl.xml b/erts/doc/src/erl.xml
index 7b90a1ccca..436c2c57e1 100644
--- a/erts/doc/src/erl.xml
+++ b/erts/doc/src/erl.xml
@@ -915,6 +915,13 @@
number of dirty CPU schedulers online can be changed at run time via
<seealso marker="erlang#system_flag_dirty_cpu_schedulers_online">erlang:system_flag(dirty_cpu_schedulers_online, DirtyCPUSchedulersOnline)</seealso>.
</p>
+ <p>
+ The amount of dirty CPU schedulers is limited by the amount of
+ normal schedulers in order to limit the effect on processes
+ executing on ordinary schedulers. If the amount of dirty CPU
+ schedulers was allowed to be unlimited, dirty CPU bound jobs would
+ potentially starve normal jobs.
+ </p>
<p>This option is ignored if the emulator doesn't have threading support
enabled. Currently, <em>this option is experimental</em> and is supported only
if the emulator was configured and built with support for dirty schedulers
@@ -944,7 +951,7 @@
enabled (it's disabled by default).
</p>
</item>
- <tag><marker id="+SDio"/><c><![CDATA[+SDio IOSchedulers]]></c></tag>
+ <tag><marker id="+SDio"/><c><![CDATA[+SDio DirtyIOSchedulers]]></c></tag>
<item>
<p>Sets the number of dirty I/O scheduler threads to create when threading
support has been enabled. The valid range is 0-1024. By default, the number
@@ -952,6 +959,16 @@
threads in the <seealso marker="#async_thread_pool_size">async thread pool
</seealso>.
</p>
+ <p>
+ The amount of dirty IO schedulers is not limited by the amount of
+ normal schedulers <seealso marker="#+SDcpu">like the amount of
+ dirty CPU schedulers</seealso>. This since only I/O bound work is
+ expected to execute on dirty I/O schedulers. I/O bound jobs are
+ expected to either block waiting for I/O, and/or spend a limited
+ amount of time moving data. However, if the user should schedule CPU
+ bound jobs on dirty I/O schedulers, these jobs might starve ordinary
+ jobs executing on ordinary schedulers.
+ </p>
<p>This option is ignored if the emulator doesn't have threading support
enabled. Currently, <em>this option is experimental</em> and is supported only
if the emulator was configured and built with support for dirty schedulers