Am Wed, 07 Apr 2010 16:39:41 +0200 schrieb Troels Arvin:
> Hello,
>
> I'm conducting some performancetests with KVM-virtualized CentOSes. One
> thing I noticed is that guest I/O performance seems to be significantly
> better for virtio-based block devices ("drive"s) if the cache=none
> argument is used. (This was with a rather powerful storage system
> backend which is hard to saturate.)
>
> So: Why isn't cache=none be the default for drives?
while ago i suffered poor performance of virtio and win2008.
This helped alot:
I enabled "deadline" block scheduler instead of the default "cfq" on the
host system. tested with: Host Debian with scheduler deadline, Guest
Win2008 with Virtio and cache=none. (26MB/s to 50MB/s boost measured)
Maybe this is also true for Linux/Linux.
I expect that scheduler "noop" for linux guests would be good.
- Thomas
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