[erlang-patches] patch to add option to set schedulers by percentage
Lukas Larsson
lukas@REDACTED
Fri Aug 23 10:39:58 CEST 2013
Hello,
This looks great! I'll add it to our tests during the weekend and if
nothing pops up merge it next week.
Lukas
On 22/08/13 20:58, Steve Vinoski wrote:
> I've amended the commit on my branch as described in my previous
> message, please refetch.
>
> https://github.com/erlang/otp/pull/58
>
> thanks,
> --steve
>
>
>
> On Thu, Aug 22, 2013 at 12:55 PM, Steve Vinoski <vinoski@REDACTED
> <mailto:vinoski@REDACTED>> wrote:
>
> Hi Lukas,
>
> Thanks for the feedback. After our IRC conversation today covering
> the details of this issue, I agree it's clearer if this patch
> doesn't introduce order dependencies between +S and +SP options or
> introduce accumulated effects of multiple +SP options. I'll change
> my branch to do the following:
>
> * ensure that later +SP options on the command line completely
> replace any previous +SP options, so there's no accumulated
> effects between them (which implies "+SP 100:100" can undo any
> previous +SP options)
>
> * keep interactions between +S and +SP options, but remove
> ordering dependencies, thus your example "+S 16:16 +SP 50:50 +S
> 16:16" would result in [8:8] as you've specified, as would both
> "+SP 50:50 +S 16:16" and "+S 16:16 +SP 50:50"
>
> * document and add tests for the already-existing feature that +S
> 0:0 undoes any prior +S options, resetting scheduler thread and
> scheduler thread online counts to their defaults for the host
>
> * document and add tests for the already-existing feature that
> specifying negative numbers for +S results in the specified values
> being subtracted from the scheduler thread and scheduler thread
> online counts
>
> I'll send another email when the branch is ready with these
> changes. Any other concerns, please let me know.
>
> thanks,
> --steve
>
>
>
> On Thu, Aug 22, 2013 at 10:11 AM, Lukas Larsson <lukas@REDACTED
> <mailto:lukas@REDACTED>> wrote:
>
> Hello Steve,
>
> Have you given any thoughts on what should happen if you chain
> multiple +SP commands? i.e.
>
> erl +S 16:16 +SP 50:50 +SP 50:50
>
> Our view right now is that this should give [8:8] and not
> [4:4] as it currently does in the patch.
>
> Related to this we also do not think that the order to +S vs
> +SP commands should matter. i.e.
>
> erl +S 16:16 +SP 50:50 +S 16:16
>
> should give [8:8] and not [16:16].
>
> What do you think? These things are for sure odd cases to
> think about, but if it is possible someone will for sure do it....
>
> Lukas
>
>
> On 21/08/13 15:45, Steve Vinoski wrote:
>> For applications where measurements show enhanced performance
>> from the use of a non-default number of emulator scheduler
>> threads, having to accurately set the right number of
>> scheduler threads across multiple hosts each with different
>> numbers of logical processors is difficult because the erl +S
>> option requires absolute numbers of scheduler threads and
>> scheduler threads online to be specified.
>>
>> To address this issue, this patch adds a +SP option to erl,
>> similar to the existing +S option but allowing the number of
>> scheduler threads and scheduler threads online to be set as
>> percentages of logical processors configured and logical
>> processors available, respectively. For example, "+SP 50:25"
>> 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.
>>
>> https://github.com/erlang/otp/pull/58
>>
>> --steve
>>
>>
>> _______________________________________________
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>> erlang-patches@REDACTED <mailto:erlang-patches@REDACTED>
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>
>
>
>
>
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