linux-kernel - Re: [PATCH] mm: vmscan: consistent update to pgrefill

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Date:   Fri, 10 Jul 2020 20:24:47 -0700
From:   Shakeel Butt <shakeelb@...gle.com>
To:     Roman Gushchin <guro@...com>
Cc:     Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Yafang Shao <laoar.shao@...il.com>,
        Chris Down <chris@...isdown.name>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linux MM <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm: vmscan: consistent update to pgrefill

On Fri, Jul 10, 2020 at 7:32 PM Roman Gushchin <guro@...com> wrote:
>
> On Fri, Jul 10, 2020 at 06:14:59PM -0700, Shakeel Butt wrote:
> > The vmstat pgrefill is useful together with pgscan and pgsteal stats to
> > measure the reclaim efficiency. However vmstat's pgrefill is not updated
> > consistently at system level. It gets updated for both global and memcg
> > reclaim however pgscan and pgsteal are updated for only global reclaim.
> > So, update pgrefill only for global reclaim. If someone is interested in
> > the stats representing both system level as well as memcg level reclaim,
> > then consult the root memcg's memory.stat instead of /proc/vmstat.
> >
> > Signed-off-by: Shakeel Butt <shakeelb@...gle.com>
>
> So you went into the opposite direction from the "previous version"
> ( https://lkml.org/lkml/2020/5/7/1464 ) ?
>

Yes because we already had those stats in the root memcg and exposing
root memcg's memory.stat resolved the issue.

> Acked-by: Roman Gushchin <guro@...com>

Thanks a lot.