From: Christoph Hellwig <hch@infradead.org>
To: Dave Chinner <david@fromorbit.com>
Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
xfs@oss.sgi.com, Mel Gorman <mgorman@suse.de>,
linux-kernel@vger.kernel.org
Subject: Re: [MMTests] IO metadata on XFS
Date: Mon, 2 Jul 2012 02:32:26 -0400 [thread overview]
Message-ID: <20120702063226.GA32151@infradead.org> (raw)
In-Reply-To: <20120701235458.GM19223@dastard>
On Mon, Jul 02, 2012 at 09:54:58AM +1000, Dave Chinner wrote:
> That will be caused by the fact we changed all the metadata updates
> to be logged, which means a transaction every time .dirty_inode is
> called.
>
> This should mostly go away when XFS is converted to use .update_time
> rather than .dirty_inode to only issue transactions when the VFS
> updates the atime rather than every .dirty_inode call...
I think the patch to do that conversion still needs review..
> It increases the CPU overhead (dirty_inode can be called up to 4
> times per write(2) call, IIRC), so with limited numbers of
> threads/limited CPU power it will result in lower performance. Where
> you have lots of CPU power, there will be little difference in
> performance...
When I checked it it could only be called twice, and we'd already
optimize away the second call. I'd defintively like to track down where
the performance changes happend, at least to a major version but even
better to a -rc or git commit.
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next prev parent reply other threads:[~2012-07-02 6:32 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20120620113252.GE4011@suse.de>
[not found] ` <20120629111932.GA14154@suse.de>
2012-06-29 11:25 ` [MMTests] IO metadata on XFS Mel Gorman
2012-07-01 23:54 ` Dave Chinner
2012-07-02 6:32 ` Christoph Hellwig [this message]
2012-07-02 14:32 ` Mel Gorman
2012-07-02 19:35 ` Mel Gorman
2012-07-03 0:19 ` Dave Chinner
2012-07-03 10:59 ` Mel Gorman
2012-07-03 11:44 ` Mel Gorman
2012-07-03 12:31 ` Daniel Vetter
2012-07-03 13:08 ` Mel Gorman
2012-07-03 13:28 ` Eugeni Dodonov
2012-07-04 0:47 ` Dave Chinner
2012-07-04 9:51 ` Mel Gorman
2012-07-03 13:04 ` Mel Gorman
2012-07-03 14:04 ` Daniel Vetter
2012-07-02 13:30 ` Mel Gorman
2012-07-23 21:25 ` [MMTests] Threaded IO Performance on xfs Mel Gorman
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