From: Christoph Hellwig <hch@lst.de>
To: Anthony Liguori <anthony@codemonkey.ws>
Cc: Christoph Hellwig <hch@lst.de>, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH 1/4] block: add enable_write_cache flag
Date: Wed, 2 Sep 2009 16:14:44 +0200 [thread overview]
Message-ID: <20090902141444.GA18253@lst.de> (raw)
In-Reply-To: <4A9E6F90.8060609@codemonkey.ws>
On Wed, Sep 02, 2009 at 08:13:52AM -0500, Anthony Liguori wrote:
> Does barrier=0 make a performance difference? IOW, would the typical
> default ext3 deployment show worse behavior?
I'll give it a spin.
> >A kernel defconfig compile takes between 9m40s and 9m42s with
> >data=writeback and barrieres disabled, and with fdatasync barriers
> >enabled it actually is minimally faster,
>
> If fdatasync different than fsync on ext3? Does it result in a full
> metadata commit?
ext3 honors the fdatasync flag and only does it's horrible job if the
metadata we care about is dirty, that is only if some non-timestamp
data is dirty. Which means for a non-sparse image file it does
well, while for a sparse image file needing allocations it will
cause trouble. And now that you mention it I've only tested the
non-sparse case which now is default for the management tools at
least on Fedora.
next prev parent reply other threads:[~2009-09-02 14:14 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-08-31 20:16 [Qemu-devel] [PATCH 0/4] data integrity fixes Christoph Hellwig
2009-08-31 20:16 ` [Qemu-devel] [PATCH 1/4] block: add enable_write_cache flag Christoph Hellwig
2009-08-31 22:09 ` Jamie Lokier
2009-08-31 22:16 ` Christoph Hellwig
2009-08-31 22:46 ` Jamie Lokier
2009-08-31 23:06 ` Christoph Hellwig
2009-09-01 10:38 ` Jamie Lokier
2009-08-31 22:53 ` Anthony Liguori
2009-08-31 22:55 ` Jamie Lokier
2009-08-31 22:58 ` Christoph Hellwig
2009-08-31 22:59 ` Jamie Lokier
2009-08-31 23:06 ` Christoph Hellwig
2009-08-31 23:09 ` Christoph Hellwig
2009-09-02 3:53 ` Christoph Hellwig
2009-09-02 13:13 ` Anthony Liguori
2009-09-02 14:14 ` Christoph Hellwig [this message]
2009-09-02 19:49 ` Christoph Hellwig
2009-08-31 20:17 ` [Qemu-devel] [PATCH 2/4] block: use fdatasync instead of fsync Christoph Hellwig
2009-08-31 21:51 ` Jamie Lokier
2009-08-31 21:55 ` Christoph Hellwig
2009-08-31 22:48 ` Jamie Lokier
2009-08-31 22:57 ` Christoph Hellwig
2009-09-01 15:59 ` Blue Swirl
2009-09-01 16:04 ` Christoph Hellwig
2009-09-02 0:34 ` Jamie Lokier
2009-09-02 0:37 ` Christoph Hellwig
2009-09-02 1:18 ` Jamie Lokier
2009-09-02 14:02 ` Blue Swirl
2009-09-02 14:15 ` Christoph Hellwig
2009-08-31 20:17 ` [Qemu-devel] [PATCH 3/4] block: add bdrv_aio_flush operation Christoph Hellwig
2009-09-01 10:24 ` Avi Kivity
2009-09-01 14:25 ` Christoph Hellwig
2009-08-31 20:18 ` [Qemu-devel] [PATCH 4/4] virtio-blk: add volatile writecache feature Christoph Hellwig
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