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Date: Mon, 2 Jan 2012 11:23:39 -0500
From: Christoph Hellwig <hch@infradead.org>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>,
        Stefan Hajnoczi <stefanha@gmail.com>, Minchan Kim <minchan@kernel.org>,
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        linux-kernel@vger.kernel.org, Vivek Goyal <vgoyal@redhat.com>
Subject: Re: [PATCH 0/6][RFC] virtio-blk: Change I/O path from request to BIO
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On Mon, Jan 02, 2012 at 05:18:13PM +0100, Paolo Bonzini wrote:
> >I tried a few times, and the only constant measureable
> >thing was that it regressed performance when used for rotating devices
> >in a few benchmarks.
> 
> Were you trying with cache=none or writeback?  For cache=none,
> that's exactly what I'd expect.  cache=writeback could be more
> interesting...

cache=none - cache=writeback isn't something people should ever use
except for read-only or extremly read-mostly workloads.