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Date:   Wed, 13 Mar 2019 12:00:17 -0400
From:   Johannes Weiner <hannes@cmpxchg.org>
To:     Roman Gushchin <guroan@gmail.com>
Cc:     linux-mm@kvack.org, kernel-team@fb.com,
        linux-kernel@vger.kernel.org, Tejun Heo <tj@kernel.org>,
        Rik van Riel <riel@surriel.com>,
        Michal Hocko <mhocko@kernel.org>, Roman Gushchin <guro@fb.com>
Subject: Re: [PATCH v2 5/6] mm: flush memcg percpu stats and events before
 releasing
Message-ID: <20190313160017.GA31891@cmpxchg.org>
References: <20190312223404.28665-1-guro@fb.com>
 <20190312223404.28665-6-guro@fb.com>
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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.
> 
> 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.
> 
> 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.
> 
> Signed-off-by: Roman Gushchin <guro@fb.com>

Acked-by: Johannes Weiner <hannes@cmpxchg.org>

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.