On 16.06.2011, at 00:04, Anthony Liguori wrote:
On 06/15/2011 03:13 PM, Prasad Joshi wrote:On Wed, Jun 15, 2011 at 6:10 PM, Pekka Enberg<penberg@xxxxxxxxxx> wrote:On Wed, Jun 15, 2011 at 7:30 PM, Avi Kivity<avi@xxxxxxxxxx> wrote:On 06/15/2011 06:53 PM, Pekka Enberg wrote:
- Fast QCOW2 image read-write support beating Qemu in fio benchmarks. See
the
following URL for test result details: https://gist.github.com/1026888
This is surprising. How is qemu invoked?
Prasad will have the details. Please note that the above are with Qemu
defaults which doesn't use virtio. The results with virtio are little
better but still in favor of tools/kvm.
The qcow2 image used for testing was copied on to /dev/shm to avoid
the disk delays in performance measurement.
QEMU was invoked with following parameters
$ qemu-system-x86_64 -hda<disk image on hard disk> -hdb
/dev/shm/test.qcow2 -m 1024M
Looking more closely at native KVM tools, you would need to use the following invocation to have an apples-to-apples comparison:
qemu-system-x86_64 -drive file=/dev/shm/test.qcow2,cache=writeback,if=virtio
Wouldn't this still be using threaded AIO mode? I thought KVM tools used native AIO?
/* blk device ?*/
disk = blkdev__probe(filename, &st);
if (disk)
return disk;
fd = open(filename, readonly ? O_RDONLY : O_RDWR);
if (fd < 0)
return NULL;
/* qcow image ?*/
disk = qcow_probe(fd, readonly);
if (disk)
return disk;
/* raw image ?*/
disk = raw_image__probe(fd, &st, readonly);
if (disk)
return disk;
Alex