Re: [Qemu-devel] [PATCH 0/3] block: Handle multiple write requests at once

[Christoph Hellwig]

On Wed, Sep 02, 2009 at 09:27:11AM +0200, Kevin Wolf wrote:
> > Of course using a sane filesystem in the guest would also fix it,
> > but the point of virtualization is at least partially to keep all
> > that old crap working nicely.
> 
> Not sure what your definition of "old crap" is, but ext3 seems to meet
> it. I don't think it's irrelevant.

Even ext3 should not do it as the elevator would merge the requests.
Do you happen to run a kernel which accidentally turned on the misnamed
and misguided SSD flag on for virtio?  That would explain sending
lots tiny I/Os.  You can checks this with a:

        cat /sys/block/vd*/queue/rotational

if a 0 turns up somewhere we have the problem.