From: Jan Kara <jack@suse.cz>
To: Andrew Perepechko <anserper@yandex.ru>
Cc: linux-fsdevel@vger.kernel.org
Subject: Re: quota: dqio_mutex design
Date: Fri, 3 Mar 2017 11:08:42 +0100 [thread overview]
Message-ID: <20170303100842.GB4373@quack2.suse.cz> (raw)
In-Reply-To: <10928956.Fla3vXZ7d9@panda>
Hello!
On Thu 02-02-17 15:23:44, Andrew Perepechko wrote:
> We have a heavy metadata related workload (ext4, quota journalling)
> and profiling shows that there's significant dqio_mutex contention.
>
> From the quota code, it looks like every time dqio_mutex is taken
> it protects access to only one quota file.
>
> Is it possible to split dqio_mutex for each of MAXQUOTAS so that
> e.g. 2 parallel dquot_commit()'s can be running for user and group
> quota update? Am I missing any dqio_mutex function that requires
> dqio_mutex to be monolithic?
So we can certainly make dqio_mutex less heavy. Making it per-quota-type
would OK but I suspect it will not bring a big benefit. What would likely
be more noticeable is if we avoided dqio_mutex for updates of quota
information - that should not be that hard to do since we update that
in-place and so don't really need the serialization for anything
substantial. However we will need some restructuring of the code to make
such locking scheme possible in a clean way...
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
next prev parent reply other threads:[~2017-03-03 11:23 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-02 12:23 quota: dqio_mutex design Andrew Perepechko
2017-03-03 10:08 ` Jan Kara [this message]
2017-03-09 22:29 ` Andrew Perepechko
2017-03-13 8:44 ` Jan Kara
2017-06-21 10:52 ` Jan Kara
[not found] ` <4181747.CBilgxvOab@panda>
2017-08-01 13:02 ` Jan Kara
2017-08-02 16:25 ` Jan Kara
2017-08-02 17:52 ` Andrew Perepechko
2017-08-03 11:09 ` Jan Kara
2017-08-03 11:31 ` Wang Shilong
2017-08-03 12:24 ` Andrew Perepechko
2017-08-03 13:19 ` Wang Shilong
2017-08-03 13:41 ` Andrew Perepechko
2017-08-03 13:55 ` Andrew Perepechko
2017-08-03 14:23 ` Jan Kara
2017-08-03 14:36 ` Jan Kara
2017-08-03 14:39 ` Wang Shilong
2017-08-08 16:06 ` Jan Kara
2017-08-14 3:24 ` Wang Shilong
2017-08-14 3:28 ` Wang Shilong
2017-08-14 3:53 ` Wang Shilong
2017-08-14 8:22 ` Jan Kara
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