Re: IO on guest is 20 times slower than host

Avi Kivity
2009-03-25T16:55:06Z

Kurt Yoder wrote:
>
> I upped the memory on the VM to 1 GB and ran the same test. It
> actually got *slower*:
>
> me@guest:~$ free
> total used free shared buffers cached
> Mem: 1024224 131324 892900 0 1816 18328
> -/+ buffers/cache: 111180 913044
> Swap: 488248 0 488248
> me@guest:~$ sudo -s
> me@guest:~# dd if=/dev/zero of=/bigfile count=100000
> 100000+0 records in
> 100000+0 records out
> 51200000 bytes (51 MB) copied, 22.2141 s, 2.3 MB/s
>

Wierd. Can you change the disk interface to ide to rule out virtio issues?

(though dd should be running entirely in cache)

Is your disk a raw volume or qcow file?

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