On Mon, 2010-03-22 at 20:16 +0200, Michael S. Tsirkin wrote: > On Sun, Mar 21, 2010 at 01:58:29PM +0200, Avi Kivity wrote: > > On 03/21/2010 01:34 PM, Michael S. Tsirkin wrote: > >> On Sun, Mar 21, 2010 at 12:29:31PM +0200, Avi Kivity wrote: > >> > >>> On 03/21/2010 12:15 PM, Michael S. Tsirkin wrote: > >>> > >>>>>> Nothing easy that I can see. Each device needs 2 of these. Avi, Gleb, > >>>>>> any objections to increasing the limit to say 16? That would give us > >>>>>> 5 more devices to the limit of 6 per guest. > >>>>>> > >>>>>> > >>>>>> > >>>>> Increase it to 200, then. > >>>>> > >>>>> > >>>> OK. I think we'll also need a smarter allocator > >>>> than bus->dev_count++ than we now have. Right? > >>>> > >>>> > >>> No, why? > >>> > >> We'll run into problems if devices are created/removed in random order, > >> won't we? > >> > > > > unregister_dev() takes care of it. > > > >>> Eventually we'll want faster scanning than the linear search we employ > >>> now, though. > >>> > >> Yes I suspect with 200 entries we will :). Let's just make it 16 for > >> now? > >> > > > > Let's make it 200 and fix the performance problems later. Making it 16 > > is just asking for trouble. > > I did this and performance with vhost seems to become much more noisy, > and drop by about 10% on average, even though in practice only > a single device is created. Still trying to figure it out ... > Any idea?
I am not sure if this 10% variation is due to the increase of NR_IO_BUS_DEVS. In our testing, we do see variations of 10% or higher between multiple netperf instances with the same setup/configuration when using virtio/vhost. Thanks Sridhar -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
