linux-kernel - Re: [PATCH v4 6/7] sched/fair: skip busy cores in SIS search

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Message-ID: <3790fb8b-db91-b528-c574-b188c5d8d2fd@bytedance.com>
Date:   Wed, 22 Jun 2022 12:03:38 +0800
From:   Abel Wu <wuyun.abel@...edance.com>
To:     Chen Yu <yu.c.chen@...el.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Mel Gorman <mgorman@...e.de>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Josh Don <joshdon@...gle.com>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        K Prateek Nayak <kprateek.nayak@....com>,
        "Gautham R . Shenoy" <gautham.shenoy@....com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 6/7] sched/fair: skip busy cores in SIS search


On 6/22/22 2:14 AM, Chen Yu Wrote:
> Hi Abel,
> On Sun, Jun 19, 2022 at 08:04:50PM +0800, Abel Wu wrote:
>> Try to improve efficiency of SIS domain search by filtering out busy
>> cores, and as a result the more overloaded the system is, the less
>> cpus will be scanned.
>>
>> The filter is supposed to contain unoccupied cpus of the LLC. And we
>> propagate these cpus to the filter one at a time at core granule.
>> This can help spreading load to different cores given that the search
>> depth is limited. The chosen cpu to be propagated is guaranteed to be
>> unoccupied at that time.
>>
>> When idle cpu exists, the last one is preferred in order not to
>> conflict with periodic load balancing during which the first idle
>> cpu (if any) is chosen to be fed with tasks.
>>
> Maybe the content in cover letter could be copied into this git log for
> future reference?

Definitely. Will fix this in next version.
Thanks.