Michael S. Tsirkin wrote:
On Mon, Mar 22, 2010 at 05:34:04PM -0700, Badari Pulavarty wrote:
Write Results:
==============
I see degraded IO performance when doing sequential IO write
tests with vhost-blk compared to virtio-blk.
# time dd of=/dev/vda if=/dev/zero bs=2M oflag=direct
I get ~110MB/sec with virtio-blk, but I get only ~60MB/sec with
vhost-blk. Wondering why ?
Try to look and number of interrupts and/or number of exits.
It could also be that you are overrunning some queue.
Yeah.
I don't see any exit mitigation strategy in your patch:
when there are already lots of requests in a queue, it's usually
a good idea to disable notifications and poll the
queue as requests complete. That could help performance.
Thanks for the suggestions. I will take a closer look.
Thanks,
Badari
