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Message-ID: <20240527080503.GU22557@noisy.programming.kicks-ass.net>
Date: Mon, 27 May 2024 10:05:03 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Mike Galbraith <efault@....de>, kprateek.nayak@....com
Cc: Chunxin Zang <spring.cxz@...il.com>, mingo@...hat.com,
juri.lelli@...hat.com, vincent.guittot@...aro.org,
dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
mgorman@...e.de, bristot@...hat.com, vschneid@...hat.com,
linux-kernel@...r.kernel.org, yu.c.chen@...el.com,
yangchen11@...iang.com, zhouchunhua@...iang.com,
zangchunxin@...iang.com
Subject: Re: [PATCH] sched/fair: Reschedule the cfs_rq when current is
ineligible
On Sat, May 25, 2024 at 08:41:28AM +0200, Mike Galbraith wrote:
> - if (pick_eevdf(cfs_rq) == pse)
> - goto preempt;
> -
> - return;
> + if (pick_eevdf(cfs_rq) == se)
> + return;
Right, this will preempt more.
This is probably going to make Prateek's case worse though. Then again,
I was already leaning to towards not making his stronger slice
protection default, because it simply hurts too much elsewhere.
Still, his observation that placing tasks can move V left which in turn
can cause the just scheduled in current non-eligible and cause
over-scheduling is valid -- just not sure what to do about it yet.
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