linux-kernel - Re: dm bufio: Reduce dm_bufio

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Message-ID: <20180801070312.GC16767@dhcp22.suse.cz>
Date:   Wed, 1 Aug 2018 09:03:12 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     jing xia <jing.xia.mail@...il.com>
Cc:     Mikulas Patocka <mpatocka@...hat.com>,
        Mike Snitzer <snitzer@...hat.com>, agk@...hat.com,
        dm-devel@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: dm bufio: Reduce dm_bufio_lock contention

On Wed 01-08-18 10:48:00, jing xia wrote:
> We reproduced this issue again and found out the root cause.
> dm_bufio_prefetch() with dm_bufio_lock enters the direct reclaim and
> takes a long time to do the soft_limit_reclaim, because of the huge
> number of memory excess of the memcg.
> Then, all the task who do shrink_slab() wait for  dm_bufio_lock.
> 
> Any suggestions for this?Thanks.

Do not use soft limit?
-- 
Michal Hocko
SUSE Labs