linux-kernel - Re: Re: [PATCH 05/15] sched/fair: Implement an EEVDF like policy

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Message-ID: <bdddc6f5-5e17-445b-bd86-dc14a8d17866@bytedance.com>
Date:   Wed, 11 Oct 2023 19:49:52 +0800
From:   Abel Wu <wuyun.abel@...edance.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Benjamin Segall <bsegall@...gle.com>, mingo@...nel.org,
        vincent.guittot@...aro.org, linux-kernel@...r.kernel.org,
        juri.lelli@...hat.com, dietmar.eggemann@....com,
        rostedt@...dmis.org, mgorman@...e.de, bristot@...hat.com,
        corbet@....net, qyousef@...alina.io, chris.hyser@...cle.com,
        patrick.bellasi@...bug.net, pjt@...gle.com, pavel@....cz,
        qperret@...gle.com, tim.c.chen@...ux.intel.com, joshdon@...gle.com,
        timj@....org, kprateek.nayak@....com, yu.c.chen@...el.com,
        youssefesmat@...omium.org, joel@...lfernandes.org, efault@....de,
        tglx@...utronix.de
Subject: Re: Re: [PATCH 05/15] sched/fair: Implement an EEVDF like policy

On 10/11/23 3:33 PM, Peter Zijlstra Wrote:
> On Wed, Oct 11, 2023 at 12:14:30PM +0800, Abel Wu wrote:
> 
>> there are cases worthy of breaking the 'eligible' rule.
> 
> See the discussion with Youssef, if we weaken the eligible rule you get
> horrific interference because you end up placing new tasks around the
> 0-lag point.

I have just begun studying the EEVDF scheduler, and obviously there
are lots of things to catch up with :)

At a quick glance at Youssef's first reply, I'm sure that's exactly
the same as I thought about, the EVDF. The intention behind is w/o
eligibility the task_timeline can be organized by deadline rather
than vruntime, hence task selection can be done in O(1) while the
min_vruntime can be updated through augmented rbtree.

Anyway, I will learn from your discussion with Youssef first, thanks
for providing the info!

Best,
	Abel