From: Christoph Hellwig <hch@infradead.org>
To: Alun <alun.linux@ty-penguin.org.uk>
Cc: kzak@redhat.com, util-linux@vger.kernel.org
Subject: Re: [PATCH] Add option to fsfreeze to call syncfs() prior to freezing.
Date: Fri, 7 Dec 2012 07:44:15 -0500 [thread overview]
Message-ID: <20121207124415.GA28504@infradead.org> (raw)
In-Reply-To: <20121207101400.5e46ba48@pcebbj.staff.aber.ac.uk>
On Fri, Dec 07, 2012 at 10:14:00AM +0000, Alun wrote:
> Hi,
>
> I've recently been looking into a problem on a heavily loaded fileserver.
> Running fsfreeze on the filesystem causes the load average to go sky high.
> Looking at the kernel sources, I discovered that the FIFREEZE ioctl suspends
> writes, then syncs the filesystem. With a large amount of dirty data, this
> can leave writes suspended for a significant time, even if your intent is to
> have the filesystem frozen for a short time. I raised this on the kernel
> list, suggesting an extra call to sync the filesystem prior to suspending
> writes, but it was pointed out to me that this would change the semantics
> of the ioctl.
It might be better to send a kernel patch to do a first async sync
attempt instead of band aiding this in one of the consumers.
next prev parent reply other threads:[~2012-12-07 12:44 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-07 10:14 [PATCH] Add option to fsfreeze to call syncfs() prior to freezing Alun
2012-12-07 11:17 ` Alun
2012-12-07 12:44 ` Christoph Hellwig [this message]
2012-12-07 12:50 ` Alun
2012-12-08 12:47 ` Christoph Hellwig
2012-12-08 19:46 ` Alun
2013-03-20 13:28 ` Karel Zak
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