From: Christoph Hellwig <hch@lst.de>
To: Anthony Liguori <anthony@codemonkey.ws>
Cc: Kevin Wolf <kwolf@redhat.com>, Avi Kivity <avi@redhat.com>,
Christoph Hellwig <hch@lst.de>,
Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>,
Qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] Default cache mode
Date: Wed, 29 Jun 2011 16:52:48 +0200 [thread overview]
Message-ID: <20110629145248.GC17085@lst.de> (raw)
In-Reply-To: <4E0B3493.4080706@codemonkey.ws>
On Wed, Jun 29, 2011 at 09:20:03AM -0500, Anthony Liguori wrote:
> Sorry, I meant having a new cache option (maybe diskcache). Semantics
> would be:
>
> diskcache=on,wce=on 0
> diskcache=on,wce=off O_SYNC
> diskcache=off,wce=on O_DIRECT
> diskcache=off,wce=off O_DIRECT | O_SYNC
>
> ignore_flush could be another option too.
Please make it two options instead of a two-dimensional one.
E.g. e hostcache=[on,off] option for the drive command line,
where fake is the equivalent of the current code together with
> I think developers usually want diskcache=on but I also agree that usually
> in production, you want diskcache=off.
Why would you want to not use O_DIRECT as a developer? Especially for
desktop setups where the VM images might be on a common use filesystem
not using O_DIRECT a deathly option for performance.
next prev parent reply other threads:[~2011-06-29 14:52 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-29 11:59 [Qemu-devel] Default cache mode Kevin Wolf
2011-06-29 12:06 ` Anthony Liguori
2011-06-29 12:16 ` Kevin Wolf
2011-06-29 12:23 ` Anthony Liguori
2011-06-29 12:32 ` Kevin Wolf
2011-06-29 13:51 ` Christoph Hellwig
2011-06-29 14:17 ` Michael Tokarev
2011-06-29 14:50 ` Christoph Hellwig
2011-06-29 15:07 ` Michael Tokarev
2011-06-29 13:50 ` Christoph Hellwig
2011-06-29 14:13 ` Anthony Liguori
2011-06-29 14:47 ` Christoph Hellwig
2011-06-29 16:03 ` Stefan Hajnoczi
2011-06-29 13:53 ` Frediano Ziglio
2011-06-29 14:11 ` Kevin Wolf
2011-06-29 14:12 ` Christoph Hellwig
2011-06-29 14:21 ` Kevin Wolf
2011-06-29 13:49 ` Christoph Hellwig
2011-06-29 12:08 ` Anthony Liguori
2011-06-29 13:55 ` Christoph Hellwig
2011-06-29 14:20 ` Anthony Liguori
2011-06-29 14:52 ` Christoph Hellwig [this message]
2011-06-29 15:26 ` Anthony Liguori
2011-06-29 12:21 ` Alexander Graf
2011-06-29 13:57 ` Stefan Hajnoczi
2011-06-29 14:05 ` Alexander Graf
2011-06-29 12:52 ` Stefan Hajnoczi
2011-06-29 13:56 ` Christoph Hellwig
2011-06-29 13:00 ` Avi Kivity
2011-06-29 13:05 ` Anthony Liguori
2011-06-29 13:30 ` Avi Kivity
2011-06-29 13:11 ` Kevin Wolf
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