linux-kernel - Re: [RFC][PATCH 13/16] sched: Add core wide task selection and scheduling.

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Date:   Fri, 19 Apr 2019 16:16:19 -0700
From:   Subhra Mazumdar <subhra.mazumdar@...cle.com>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     Julien Desfossez <jdesfossez@...italocean.com>,
        Peter Zijlstra <peterz@...radead.org>, tglx@...utronix.de,
        pjt@...gle.com, tim.c.chen@...ux.intel.com,
        torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org,
        fweisbec@...il.com, keescook@...omium.org, kerrnel@...gle.com,
        Vineeth Pillai <vpillai@...italocean.com>,
        Nishanth Aravamudan <naravamudan@...italocean.com>,
        Aaron Lu <aaron.lu@...ux.alibaba.com>
Subject: Re: [RFC][PATCH 13/16] sched: Add core wide task selection and
 scheduling.


On 4/19/19 1:40 AM, Ingo Molnar wrote:
> * Subhra Mazumdar <subhra.mazumdar@...cle.com> wrote:
>
>> I see similar improvement with this patch as removing the condition I
>> earlier mentioned. So that's not needed. I also included the patch for the
>> priority fix. For 2 DB instances, HT disabling stands at -22% for 32 users
>> (from earlier emails).
>>
>>
>> 1 DB instance
>>
>> users  baseline   %idle    core_sched %idle
>> 16     1          84       -4.9% 84
>> 24     1          76       -6.7% 75
>> 32     1          69       -2.4% 69
>>
>> 2 DB instance
>>
>> users  baseline   %idle    core_sched %idle
>> 16     1          66       -19.5% 69
>> 24     1          54       -9.8% 57
>> 32     1          42       -27.2%        48
> So HT disabling slows down the 2DB instance by -22%, while core-sched
> slows it down by -27.2%?
>
> Would it be possible to see all the results in two larger tables (1 DB
> instance and 2 DB instance) so that we can compare the performance of the
> 3 kernel variants with each other:
>
>   - "vanilla +HT": Hyperthreading enabled,  vanilla scheduler
>   - "vanilla -HT": Hyperthreading disabled, vanilla scheduler
>   - "core_sched":  Hyperthreading enabled,  core-scheduling enabled
>
> ?
>
> Thanks,
>
> 	Ingo
Following are the numbers. Disabling HT gives improvement in some cases.

1 DB instance

users  vanilla+HT   core_sched vanilla-HT
16     1            -4.9% -11.7%
24     1            -6.7% +13.7%
32     1            -2.4% +8%

2 DB instance

users  vanilla+HT   core_sched vanilla-HT
16     1            -19.5% +5.6%
24     1            -9.8% +3.5%
32     1            -27.2%        -22.8%