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

[Kevin Wolf]

Christoph Hellwig schrieb:
> 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. 

It's a RHEL 5.3 installation, and the kernel doesn't seem to even
provide this file. However, I think I read that this is an issue of
relatively new kernels, so probably not?

What could matter, though, is that the installer uses LVM for the
standard layout which I'm using. Does this make a difference in that
respect?

Kevin