From: Christoph Hellwig <hch@infradead.org>
To: Dave Chinner <david@fromorbit.com>
Cc: Christoph Hellwig <hch@infradead.org>,
Theodore Tso <tytso@mit.edu>,
Chris Mason <chris.mason@oracle.com>,
linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org,
xfs@oss.sgi.com
Subject: Re: ext4 writepages is making tiny bios?
Date: Thu, 3 Sep 2009 12:42:09 -0400 [thread overview]
Message-ID: <20090903164209.GA28384@infradead.org> (raw)
In-Reply-To: <20090903055201.GA7146@discord.disaster>
On Thu, Sep 03, 2009 at 03:52:01PM +1000, Dave Chinner wrote:
> > XFS did the mistake of trusting the VM, while everyone more or less
> > overrode it. Removing all those checks and writing out much larger
> > data fixes it with a relatively small patch:
> >
> > http://verein.lst.de/~hch/xfs/xfs-writeback-scaling
>
> Careful:
>
> - tloff = min(tlast, startpage->index + 64);
> + tloff = min(tlast, startpage->index + 8192);
>
> That will cause 64k page machines to try to write back 512MB at a
> time. This will re-introduce similar to the behaviour in sles9 where
> writeback would only terminate at the end of an extent (because the
> mapping end wasn't capped like above).
Pretty good point, any applies to all the different things we discussed
recently. Ted, should be maybe introduce a max_writeback_mb instead of
the max_writeback_pages in the VM, too?
next prev parent reply other threads:[~2009-09-03 16:42 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-01 18:44 ext4 writepages is making tiny bios? Chris Mason
2009-09-01 20:57 ` Theodore Tso
2009-09-01 21:27 ` Christoph Hellwig
2009-09-02 0:17 ` Chris Mason
2009-09-03 5:52 ` Dave Chinner
2009-09-03 16:42 ` Christoph Hellwig [this message]
2009-09-04 0:15 ` Theodore Tso
2009-09-04 7:20 ` Jens Axboe
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