Re: [Xen-devel] poor I/O performance on domU

[Jan Kundrát <jan.kundrat@xxxxxx>]

Anthony Liguori wrote:
> I think that's a reasonable answer.  It should be easy to test though. 
> Try your same test on dom0 and use /dev/loopN where N is the loopback
> device that has your rootfs on it.
Only rootfs is exported from loopback device and I'm benchmarking access 
to dom0's /dev/hda exported to domU as read-only.
As the rootfs image is quite small (16MB), I can't easily test access 
speeds because it will fit into cache.
> The difference between testing /dev/loopN access on dom0 and the virtual
> block device on domU should tell you the Xen-imposed performance
> penalty.
>
> I did a quick test on my system and there was a 50% slowdown using the
> loopback device doing your test so I imagine it's that.
Accessing exported loopback or some other device?


-jkt

--
cd /local/pub && more beer > /dev/mouth



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