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 21:49:12 +0200 [thread overview]
Message-ID: <20090902194912.GA490@lst.de> (raw)
In-Reply-To: <4A9E6F90.8060609@codemonkey.ws>
On Wed, Sep 02, 2009 at 08:13:52AM -0500, Anthony Liguori wrote:
> >performance should be kind of a worst case. All these patches are
> >with Linux 2.6.31-rc8 + my various barrier fixes on guest and host,
> >using ext3 with barrier=1 on both.
> >
>
> Does barrier=0 make a performance difference? IOW, would the typical
> default ext3 deployment show worse behavior?
Note for this tyical ext3 deployment the barrier patches are kinda
useless, because we still don't have any data integrity guarantees at
all. Anyway, here are the numbers with barrier=0 on host and guest:
data=writeback, no write cache advertised:
9m37.890s, 9m38.303s, 9m38.423s, 9m38.861s, 9m39.599s
data=writeback, write cache advertized (and backed by fdatasync):
9m39.649s, 9m39.772s, 9m40.149s, 9m41.737s, 9m41.996s
next prev parent reply other threads:[~2009-09-02 19:49 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
2009-09-02 19:49 ` Christoph Hellwig [this message]
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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