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Date: Wed, 29 Jun 2011 07:08:18 -0500
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: Re: [Qemu-devel] Default cache mode
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To: Kevin Wolf <kwolf@redhat.com>
Cc: Avi Kivity <avi@redhat.com>, Christoph Hellwig <hch@lst.de>, Qemu-devel@nongnu.org, Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

On 06/29/2011 06:59 AM, Kevin Wolf wrote:
> Hi,
>
> I think we have touched this topic before during some IRC discussions or
> somewhere deep in a mailing list thread, but I think it hasn't been
> discussed on the list.
>
> Our default cache mode of cache=writethrough is extremely conservative
> and provides absolute safety at the cost of performance,


Thinking twice about this, shouldn't we just move to a simplified model:

-drive file=foo.img,cache=[on|off],hd0  -device 
virtio-blk-pci,drive=hd0,wce=1

As long as we advertise wce and wce can be toggled from the guest, I 
don't think the default is all that important.  I think cache=on is the 
right default for most common use cases.

Regards,

Anthony Liguori