From: Johannes Weiner <hannes@cmpxchg.org>
To: Yafang Shao <laoar.shao@gmail.com>
Cc: akpm@linux-foundation.org, linux-mm@kvack.org,
Michal Hocko <mhocko@kernel.org>,
Vladimir Davydov <vdavydov.dev@gmail.com>,
Yafang Shao <shaoyafang@didiglobal.com>
Subject: Re: [PATCH v2] mm/memcontrol: keep local VM counters in sync with the hierarchical ones
Date: Thu, 11 Jul 2019 11:19:20 -0400 [thread overview]
Message-ID: <20190711151920.GA20341@cmpxchg.org> (raw)
In-Reply-To: <1562851979-10610-1-git-send-email-laoar.shao@gmail.com>
On Thu, Jul 11, 2019 at 09:32:59AM -0400, Yafang Shao wrote:
> After commit 815744d75152 ("mm: memcontrol: don't batch updates of local VM stats and events"),
> the local VM counters is not in sync with the hierarchical ones.
>
> Bellow is one example in a leaf memcg on my server (with 8 CPUs),
> inactive_file 3567570944
> total_inactive_file 3568029696
> We can find that the deviation is very great, that is because the 'val' in
> __mod_memcg_state() is in pages while the effective value in
> memcg_stat_show() is in bytes.
> So the maximum of this deviation between local VM stats and total VM
> stats can be (32 * number_of_cpu * PAGE_SIZE), that may be an unacceptable
> great value.
>
> We should keep the local VM stats in sync with the total stats.
> In order to keep this behavior the same across counters, this patch updates
> __mod_lruvec_state() and __count_memcg_events() as well.
>
> Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Michal Hocko <mhocko@kernel.org>
> Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
> Cc: Yafang Shao <shaoyafang@didiglobal.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
next prev parent reply other threads:[~2019-07-11 15:19 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-11 13:32 Yafang Shao
2019-07-11 15:19 ` Johannes Weiner [this message]
2019-07-11 23:42 ` Andrew Morton
2019-07-12 1:47 ` Yafang Shao
2019-07-12 5:29 ` Michal Hocko
2019-07-12 6:12 ` Yafang Shao
2019-07-12 6:53 ` Michal Hocko
2019-07-12 7:14 ` Yafang Shao
2019-07-12 7:54 ` Michal Hocko
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