From mboxrd@z Thu Jan  1 00:00:00 1970
From: Gordan Bobic <gordan@bobich.net>
Subject: Re: Shouldn't cache=none be the default for drives?
Date: Wed, 07 Apr 2010 16:17:44 +0100
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Troels Arvin wrote:
> Hello,
> 
> I'm conducting some performancetests with KVM-virtualized CentOSes. One 
> thing I noticed is that guest I/O performance seems to be significantly 
> better for virtio-based block devices ("drive"s) if the cache=none 
> argument is used. (This was with a rather powerful storage system 
> backend which is hard to saturate.)
> 
> So: Why isn't cache=none be the default for drives?

Is that the right question? Or is the right question "Why is cache=none 
faster?"

What did you use for measuring the performance? I have found in the past 
that virtio block device was slower than IDE block device emulation.

Gordan