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From: Mike Snitzer <snitzer@redhat.com>
To: lilofile <lilofile@aliyun.com>
Cc: dm-devel <dm-devel@redhat.com>
Subject: Re: dm-thin  COMMIT_PERIOD problem
Date: Sat, 1 Nov 2014 14:45:02 -0400	[thread overview]
Message-ID: <20141101184502.GB21830@redhat.com> (raw)
In-Reply-To: <b827be6a-acd8-470d-94c4-6fb9a6cf114e@aliyun.com>

On Sat, Nov 01 2014 at 10:40am -0400,
lilofile <lilofile@aliyun.com> wrote:

> In dm-thin.c,COMMIT_PERIOD is set HZ, I think this value has a  impact on system impact,too frequent commit will reduce the write performance of the system?
> other method which it is submitted by  the total size of dirty data   is feasible?

It only issues IO if changes have occured.  It isn't writing to disk
every second unless changes need to get to disk anyway.

(There was a bug where it _did_ write the metadata superblock every
second even when it wasn't needed.. since fixed with this commit:
http://git.kernel.org/linus/4d1662a30 )

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      reply	other threads:[~2014-11-01 18:45 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-11-01 14:40 dm-thin COMMIT_PERIOD problem lilofile
2014-11-01 18:45 ` Mike Snitzer [this message]

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