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 _______________________________________________ Virtualization mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/virtualization
