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Re: [Xen-users] Default disk I/O scheduler in linux guest

On Tue, Apr 28, 2009 at 5:50 AM, Sadique Puthen <sputhenp@xxxxxxxxxx> wrote:
> If the underlying hardware is RAID5 done in the hardware level, using
> cfq instead of noop in the guest gives 2x performance while testing with
> a simple dd command.

i've repeated some quick tests, (i have only an md RAID1, with LVM).
bonnie didn't report any difference, but dd writes are 35% faster with
'noop' on the guest than CFQ.

what's interesting is that the Dom0's CPU usage is almost half with
CFQ than NOOP, so my wild guess is that in your case you're bound by
Dom0 more than DomU


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