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From: Gordan Bobic <gordan@bobich.net>
To: kvm@vger.kernel.org
Subject: Re: Shouldn't cache=none be the default for drives?
Date: Wed, 07 Apr 2010 16:17:44 +0100	[thread overview]
Message-ID: <4BBCA218.1020306@bobich.net> (raw)
In-Reply-To: <4BBC992D.3050905@gmail.com>

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

  reply	other threads:[~2010-04-07 15:17 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-04-07 14:39 Shouldn't cache=none be the default for drives? Troels Arvin
2010-04-07 15:17 ` Gordan Bobic [this message]
2010-04-08  5:07 ` Thomas Mueller
2010-04-08  6:05   ` Michael Tokarev
2010-04-08  6:09     ` Thomas Mueller
2010-04-08  6:23       ` Thomas Mueller
2010-04-08 10:08     ` Christoph Hellwig

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