linux-kernel - Re: [PATCH v3] sched/fair: Remove cfs_rq::nr_spread_over and cfs_rq::exec

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Message-ID: <20240724080109.GN26750@noisy.programming.kicks-ass.net>
Date: Wed, 24 Jul 2024 10:01:09 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Dietmar Eggemann <dietmar.eggemann@....com>
Cc: Chuyi Zhou <zhouchuyi@...edance.com>, mingo@...hat.com,
	juri.lelli@...hat.com, vincent.guittot@...aro.org,
	rostedt@...dmis.org, bsegall@...gle.com, chengming.zhou@...ux.dev,
	linux-kernel@...r.kernel.org,
	Vishal Chourasia <vishalc@...ux.ibm.com>,
	K Prateek Nayak <kprateek.nayak@....com>
Subject: Re: [PATCH v3] sched/fair: Remove cfs_rq::nr_spread_over and
 cfs_rq::exec_clock

On Tue, Jul 23, 2024 at 10:47:22PM +0200, Dietmar Eggemann wrote:
> On 20/07/2024 05:19, Chuyi Zhou wrote:
> > nr_spread_over tracks the number of instances where the difference
> > between a scheduling entity's virtual runtime and the minimum virtual
> > runtime in the runqueue exceeds three times the scheduler latency,
> > indicating significant disparity in task scheduling.
> > Commit 5e963f2bd465 ("sched/fair: Commit to EEVDF") removed its usage.
> > 
> > cfs_rq->exec_clock was used to account for time spent executing tasks.
> > Commit 5d69eca542ee ("sched: Unify runtime accounting across classes")
> > removed its usage.
> 
> I was under the impression this commit removed
> 'schedstat_add(cfs_rq->exec_clock, delta_exec)' from update_curr() by
> mistake?
> 
> That's why I sent out this patch back in May:
> 
> https://lkml.kernel.org/r/20240503104605.1871571-1-dietmar.eggemann@arm.com
> 
> to add it back.

Probably an accident yes. Is that exec_clock thing useful though? I
mean, I don't much care either way around.

I had a previous version of this patched lined up, but its easy enough
to press 'dd' on it.