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From:   Roman Gushchin <guro@fb.com>
To:     Johannes Weiner <hannes@cmpxchg.org>
CC:     Roman Gushchin <guroan@gmail.com>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        Kernel Team <Kernel-team@fb.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Tejun Heo <tj@kernel.org>, Rik van Riel <riel@surriel.com>,
        Michal Hocko <mhocko@kernel.org>
Subject: Re: [PATCH v2 5/6] mm: flush memcg percpu stats and events before
 releasing
Thread-Topic: [PATCH v2 5/6] mm: flush memcg percpu stats and events before
 releasing
Thread-Index: AQHU2SPIEdyFRN8G5UOFWOBkO8hY8aYJuWyAgAAn5QA=
Date:   Wed, 13 Mar 2019 18:23:09 +0000
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References: <20190312223404.28665-1-guro@fb.com>
 <20190312223404.28665-6-guro@fb.com> <20190313160017.GA31891@cmpxchg.org>
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On Wed, Mar 13, 2019 at 12:00:17PM -0400, Johannes Weiner wrote:
> On Tue, Mar 12, 2019 at 03:34:02PM -0700, Roman Gushchin wrote:
> > Flush percpu stats and events data to corresponding before releasing
> > percpu memory.
> >=20
> > Although per-cpu stats are never exactly precise, dropping them on
> > floor regularly may lead to an accumulation of an error. So, it's
> > safer to flush them before releasing.
> >=20
> > To minimize the number of atomic updates, let's sum all stats/events
> > on all cpus locally, and then make a single update per entry.
> >=20
> > Signed-off-by: Roman Gushchin <guro@fb.com>
>=20
> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
>=20
> Do you mind merging 6/6 into this one? That would make it easier to
> verify that the code added in this patch and the code removed in 6/6
> are indeed functionally equivalent.
>=20

I did try, but the result is the mess of added and removed lines,
which are *almost* the same, but are slightly different (e.g. tabs).
So it's much easier to review it as two separate patches.

Thanks!