Message-ID: <6742a778-9a9d-4457-cf0a-26218ba075dc@amd.com>
Date:   Mon, 23 Jan 2023 10:17:46 +0530
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Subject: Re: [RFC PATCH v4 0/2] sched/fair: Choose the CPU where short task is
 running during wake up
Content-Language: en-US
To:     Chen Yu <yu.c.chen@intel.com>, Yicong Yang <yangyicong@huawei.com>
Cc:     yangyicong@hisilicon.com, Peter Zijlstra <peterz@infradead.org>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Tim Chen <tim.c.chen@intel.com>,
        Mel Gorman <mgorman@techsingularity.net>,
        Juri Lelli <juri.lelli@redhat.com>,
        Rik van Riel <riel@surriel.com>,
        Aaron Lu <aaron.lu@intel.com>,
        Abel Wu <wuyun.abel@bytedance.com>,
        "Gautham R . Shenoy" <gautham.shenoy@amd.com>,
        Ingo Molnar <mingo@redhat.com>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ben Segall <bsegall@google.com>,
        Daniel Bristot de Oliveira <bristot@redhat.com>,
        Valentin Schneider <vschneid@redhat.com>,
        Hillf Danton <hdanton@sina.com>,
        Honglei Wang <wanghonglei@didichuxing.com>,
        Len Brown <len.brown@intel.com>,
        Chen Yu <yu.chen.surf@gmail.com>,
        Tianchen Ding <dtcccc@linux.alibaba.com>,
        Joel Fernandes <joel@joelfernandes.org>,
        Josh Don <joshdon@google.com>, Barry Song <21cnbao@gmail.com>,
        linux-kernel@vger.kernel.org
References: <cover.1671158588.git.yu.c.chen@intel.com>
 <5910589f-fe3e-5999-5821-7b2b8021e74b@huawei.com>
 <Y8lrnvLzGGJmlPor@chenyu5-mobl1>
 <d3d04f60-e3d7-9abb-4cfa-57790b359dd9@huawei.com>
 <Y81YRyRpg6xsyJK6@chenyu5-mobl1>
From:   K Prateek Nayak <kprateek.nayak@amd.com>
In-Reply-To: <Y81YRyRpg6xsyJK6@chenyu5-mobl1>
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Hello Chenyu,

Thank you for looking into this.

On 1/22/2023 9:07 PM, Chen Yu wrote:
> On 2023-01-20 at 17:09:28 +0800, Yicong Yang wrote:
> [..snip..]
>
> This sounds reasonable to me. I think we can further enhance it.
> And before you sending out the proposal, could you help test the following
> experimental change, to see if it makes tbench netperf and MySQL better?
> 
> Hi Prateek, could you also help check if below change would make the Spec regression
> go away?

Sure. I'll add this on top of v4 and queue some runs.
Will share the results soon.

> 
> thanks,
> Chenyu
> 
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index fc8a636eca5e..6e1ab5e2686c 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -4974,7 +4974,7 @@ wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se);
>  static inline int is_short_task(struct task_struct *p)
>  {
>  	return sched_feat(SIS_SHORT) && p->se.dur_avg &&
> -		((p->se.dur_avg * 8) <= sysctl_sched_min_granularity);
> +		((p->se.dur_avg * 1024) <= (__this_cpu_read(sd_llc_size) * sysctl_sched_min_granularity));
>  }
>  
>  /*


--
Thanks and Regards,
Prateek