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From:   Josh Don <joshdon@google.com>
Date:   Mon, 12 Dec 2022 10:17:35 -0800
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Subject: Re: [PATCH v3 1/2] sched/fair: Introduce short duration task check
To:     Chen Yu <yu.c.chen@intel.com>
Cc:     Yicong Yang <yangyicong@huawei.com>, yangyicong@hisilicon.com,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Joel Fernandes <joel@joelfernandes.org>,
        Honglei Wang <wanghonglei@didichuxing.com>,
        Peter Zijlstra <peterz@infradead.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>,
        K Prateek Nayak <kprateek.nayak@amd.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>,
        Len Brown <len.brown@intel.com>,
        Chen Yu <yu.chen.surf@gmail.com>,
        Tianchen Ding <dtcccc@linux.alibaba.com>,
        linux-kernel@vger.kernel.org
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> BTW, I've changed the threshold to (sysctl_sched_min_granularity / 8) in my next
> version, as this is the value that fit my previous test case and also not to break
> the case Josh mentioned.

Do you mean a hardcoded value of some number of micros, or literally
sched_min_granularity / 8? I don't think the latter is necessary, and
indeed can lead to weirdness if min_gran is too small or too large. I
don't think the concept of what a short duration task is should
expand/contract with min_gran.

Best,
Josh