On Fri, Jun 27, 2014 at 12:59 PM, Paolo Bonzini <pbonz...@redhat.com> wrote: > Il 27/06/2014 03:15, Ming Lei ha scritto: >> >> On Thu, Jun 26, 2014 at 11:57 PM, Paolo Bonzini <pbonz...@redhat.com> >> wrote: >>> >>> We can implement (advisory) calls like bdrv_plug/bdrv_unplug in order to >>> restore the previous levels of performance. >> >> >> Yes, that is also what I am thinking, or interfaces like bdrv_queue_io() >> and bdrv_submit_io(), which may match with aio interfaces. > > > Would you like to try preparing a patch?
OK, let me try to do that. > > >>> >>> Note that some fallout of the conversion was expected. Dataplane told us >>> experimentally what level of performance could be reached, but was a dead >>> end in terms of functionality. Now Stefan added a whole lot of >>> functionality to dataplane (accounting, throttling, file formats and >>> protocols, thread-pool based I/O, etc.) and we need to bring back any >>> performance we lost in the process. >> >> >> These features are very good, but looks the conversion is a bit early, :-( > > > Dataplane is still (and has always been) experimental. For now, it's a > playground to get rid of the big QEMU lock in hot paths. As such, > performance going up and down is expected. The good thing is that every > performance improvement we do now will not be restricted to dataplane, it > can be applied just as well to any other device. Yes, virtio-scsi may benefit from the improvement too, and other block devices too. Thanks, -- Ming Lei