On Mar 25, 2009, at 12:54 PM, Avi Kivity wrote:
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?
It was actually set as an ide disk before it was a virtio disk. I
switched it to virtio to try to get rid of this problem, but no luck
so far.
The disk lives on an LVM logical volume.
What do you mean about the cache? Is my test fundamentally flawed? I
*thought* I was testing write speed on the disk...
-Kurt
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