From: Kevin Wolf <kwolf@suse.de>
To: qemu-devel@nongnu.org
Cc: Laurent Vivier <Laurent.Vivier@libertysurf.fr>
Subject: Re: [Qemu-devel] [PATCH 0/4] qcow2: Improve cluster refcount update
Date: Fri, 07 Nov 2008 09:31:30 +0100 [thread overview]
Message-ID: <4913FCE2.3010705@suse.de> (raw)
In-Reply-To: <49133D17.3050100@codemonkey.ws>
Anthony Liguori schrieb:
> Laurent Vivier wrote:
>> This series of patches improves qcow2 performance with O_DIRECT
>> when the qcow2 file is empty and we begin to fill it.
>>
>
> I really dislike this series and any future series that does similar
> things. The real problem is that non-aligned accesses are so slow, but
> there's no reason that they must be so slow. It's because we're doing
> synchronous IO operations instead of using posix-aio like we should.
> That's the real problem. Just doing a memory copy to an aligned buffer
> is not going to cause that much performance delay.
Even if you don't like the alignment part, patches 1 and 2 are still
useful, IMHO.
Kevin
next prev parent reply other threads:[~2008-11-07 8:28 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-11-06 16:55 [Qemu-devel] [PATCH 0/4] qcow2: Improve cluster refcount update Laurent Vivier
2008-11-06 18:53 ` Anthony Liguori
2008-11-07 8:31 ` Kevin Wolf [this message]
2008-11-07 8:44 ` Laurent Vivier
2008-11-07 13:59 ` Anthony Liguori
2008-11-07 15:01 ` Laurent Vivier
2008-11-07 15:37 ` Anthony Liguori
2008-11-07 15:48 ` Laurent Vivier
2008-11-09 14:35 ` Avi Kivity
2008-11-09 16:32 ` Anthony Liguori
2008-11-10 20:15 ` Andreas Färber
2008-11-10 20:52 ` Anthony Liguori
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