From: Christoph Hellwig <hch@lst.de>
To: Anthony Liguori <anthony@codemonkey.ws>
Cc: Christoph Hellwig <hch@lst.de>,
Rusty Russell <rusty@rustcorp.com.au>,
kvm@vger.kernel.org
Subject: Re: [PATCH, RFC] virtio_blk: add cache flush command
Date: Mon, 11 May 2009 17:40:46 +0200 [thread overview]
Message-ID: <20090511154046.GA4226@lst.de> (raw)
In-Reply-To: <4A083B7C.1000703@codemonkey.ws>
On Mon, May 11, 2009 at 09:51:40AM -0500, Anthony Liguori wrote:
> What typically triggers a flush operation?
fsync.
> I would assume an fsync would, but would a flush happen after every
> O_DIRECT write?
Right now it doesn't, but it probably should.
> If the backend implementation of T_FLUSH is fsync, I would think that
> this would result in rather poor performance for O_DIRECT operations in
> the guest.
Right now it's fsync. By the time I'll submit the backend change it
will still be fsync, but at least called from the posix-aio-compat
thread pool.
next prev parent reply other threads:[~2009-05-11 15:40 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-11 8:39 [PATCH, RFC] virtio_blk: add cache flush command Christoph Hellwig
2009-05-11 14:51 ` Anthony Liguori
2009-05-11 15:40 ` Christoph Hellwig [this message]
2009-05-11 15:45 ` Avi Kivity
2009-05-11 16:28 ` Christoph Hellwig
2009-05-11 16:49 ` Avi Kivity
2009-05-11 17:47 ` Anthony Liguori
2009-05-11 18:00 ` Avi Kivity
2009-05-11 18:29 ` Anthony Liguori
2009-05-11 18:40 ` Avi Kivity
2009-05-18 12:03 ` Christoph Hellwig
2009-05-12 7:23 ` Christoph Hellwig
2009-05-12 7:19 ` Christoph Hellwig
2009-05-12 8:35 ` Avi Kivity
2009-05-18 12:06 ` Christoph Hellwig
2009-05-11 16:38 ` Anthony Liguori
2009-05-12 7:26 ` Christoph Hellwig
2009-05-12 13:54 ` Rusty Russell
2009-05-12 14:18 ` Christian Borntraeger
2009-05-13 1:52 ` Rusty Russell
2009-05-18 12:07 ` Christoph Hellwig
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