linux-kernel - Re: [PATCH 4/6] sched: make schedstats helpers independent of fair sched class

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Date:   Wed, 2 Dec 2020 10:04:54 +0800
From:   Yafang Shao <laoar.shao@...il.com>
To:     Mel Gorman <mgorman@...e.de>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Benjamin Segall <bsegall@...gle.com>, bristot@...hat.com,
        jun qian <qianjun.kernel@...il.com>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-rt-users@...r.kernel.org
Subject: Re: [PATCH 4/6] sched: make schedstats helpers independent of fair
 sched class

On Tue, Dec 1, 2020 at 8:46 PM Mel Gorman <mgorman@...e.de> wrote:
>
> On Tue, Dec 01, 2020 at 07:54:14PM +0800, Yafang Shao wrote:
> > The original prototype of the schedstats helpers are
> >
> > update_stats_wait_*(struct cfs_rq *cfs_rq, struct sched_entity *se)
> >
> > The cfs_rq in these helpers is used to get the rq_clock, and the se is
> > used to get the struct sched_statistics and the struct task_struct. In
> > order to make these helpers available by all sched classes, we can pass
> > the rq, sched_statistics and task_struct directly.
> >
> > Then the new helpers are
> >
> > update_stats_wait_*(struct rq *rq, struct task_struct *p,
> >                   struct sched_statistics *stats)
> >
> > which are independent of fair sched class.
> >
> > To avoid vmlinux growing too large or introducing ovehead when
> > !schedstat_enabled(), some new helpers after schedstat_enabled() are also
> > introduced, Suggested by Mel. These helpers are in sched/stats.c,
> >
> > __update_stats_wait_*(struct rq *rq, struct task_struct *p,
> >                     struct sched_statistics *stats)
> >
> > Cc: Mel Gorman <mgorman@...e.de>
> > Signed-off-by: Yafang Shao <laoar.shao@...il.com>
>
> Think it's ok, it's mostly code shuffling. I'd have been happier if
> there was evidence showing a before/after comparison of the sched stats
> for something simple like "perf bench sched pipe" and a clear statement
> of no functional change as well as a comparison of the vmlinux files but
> I think it's ok so;
>

Thanks for the review, I will do the comparison as you suggested.

> Acked-by: Mel Gorman <mgorman@...e.de>
>

Thanks!

> I didn't look at the rt.c parts
>
> --
> Mel Gorman
> SUSE Labs



-- 
Thanks
Yafang