From: Peter Zijlstra <peterz@infradead.org>
To: hupu@oppo.com
Cc: mingo@redhat.com, juri.lelli@redhat.com,
vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
bristot@redhat.com, vschneid@redhat.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] sched/fair.c: Fix the calculation method of 'lag'
Date: Thu, 25 Apr 2024 13:51:25 +0200 [thread overview]
Message-ID: <20240425115125.GZ40213@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <20240424085533.GS40213@noisy.programming.kicks-ass.net>
On Thu, Apr 25, 2024 at 07:44:59PM +0800, hupu@oppo.com wrote:
> > > From: hupu <hupu@oppo.com>
> > >
> > > I think the 'lag' calculation here is inaccurate.
> > >
> > > Assume that delta needs to be subtracted from v_i to ensure that the
> > > vlag of task i after placement is the same as before.
> >
> > Why ?!? v_i is the unkown, it makes no sense to complicate things by
> > adding extra unknowns.
> >
> > > At this time, the
> > > vlag of task i after placement should be:
> > > vl'_i = V' - (v_i - delta)
> >
> > But but but, you can't have V' without knowing v_i.
> >
>
> Thank you for your patient guidance. I overlooked a important fact that
> v_i is unknown in the process of proof. Below is the complete proof
> process, and it turns out that you are correct.
*phew*, thanks for checking!
prev parent reply other threads:[~2024-04-25 11:51 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-23 11:44 [PATCH] sched/fair.c: Fix the calculation method of 'lag' to ensure that the vlag of the task after placement is the same as before hupu
2024-04-24 8:55 ` Peter Zijlstra
2024-04-25 11:44 ` [PATCH] sched/fair.c: Fix the calculation method of 'lag' hupu
2024-04-25 11:51 ` Peter Zijlstra [this message]
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