On Mon, Mar 26, 2012 at 10:11:43PM +0200, Vadim Rozenfeld wrote: > On Monday, March 26, 2012 08:54:50 PM Peter Lieven wrote: > > On 26.03.2012 20:36, Vadim Rozenfeld wrote: > > > On Monday, March 26, 2012 07:52:49 PM Gleb Natapov wrote: > > >> On Mon, Mar 26, 2012 at 07:46:03PM +0200, Vadim Rozenfeld wrote: > > >>> On Monday, March 26, 2012 07:00:32 PM Peter Lieven wrote: > > >>>> On 22.03.2012 10:38, Vadim Rozenfeld wrote: > > >>>>> On Thursday, March 22, 2012 10:52:42 AM Peter Lieven wrote: > > >>>>>> On 22.03.2012 09:48, Vadim Rozenfeld wrote: > > >>>>>>> On Thursday, March 22, 2012 09:53:45 AM Gleb Natapov wrote: > > >>>>>>>> On Wed, Mar 21, 2012 at 06:31:02PM +0100, Peter Lieven wrote: > > >>>>>>>>> On 21.03.2012 12:10, David Cure wrote: > > >>>>>>>>>> hello, > > >>>>>>>>>> > > >>>>>>>>>> Le Tue, Mar 20, 2012 at 02:38:22PM +0200, Gleb Natapov ecrivait : > > >>>>>>>>>>> Try to add<feature policy='disable' name='hypervisor'/> to > > >>>>>>>>>>> cpu definition in XML and check command line. > > >>>>>>>>>>> > > >>>>>>>>>> ok I try this but I can't use<cpu model> to map the host > > >>>>>>>>>> cpu > > >>>>>>>>>> > > >>>>>>>>>> (my libvirt is 0.9.8) so I use : > > >>>>>>>>>> <cpu match='exact'> > > >>>>>>>>>> > > >>>>>>>>>> <model>Opteron_G3</model> > > >>>>>>>>>> <feature policy='disable' name='hypervisor'/> > > >>>>>>>>>> > > >>>>>>>>>> </cpu> > > >>>>>>>>>> > > >>>>>>>>>> (the physical server use Opteron CPU). > > >>>>>>>>>> > > >>>>>>>>>> The log is here : > > >>>>>>>>>> http://www.roullier.net/Report/report-3.2-vhost-net-1vcpu-cpu.tx > > >>>>>>>>>> t.gz > > >>>>>>>>>> > > >>>>>>>>>> And now with only 1 vcpu, the response time is 8.5s, great > > >>>>>>>>>> > > >>>>>>>>>> improvment. We keep this configuration for production : we check > > >>>>>>>>>> the response time when some other users are connected. > > >>>>>>>>> > > >>>>>>>>> please keep in mind, that setting -hypervisor, disabling hpet and > > >>>>>>>>> only one vcpu > > >>>>>>>>> makes windows use tsc as clocksource. you have to make sure, that > > >>>>>>>>> your vm is not switching between physical sockets on your system > > >>>>>>>>> and that you have constant_tsc feature to have a stable tsc > > >>>>>>>>> between the cores in the same socket. its also likely that the > > >>>>>>>>> vm will crash when live migrated. > > >>>>>>>> > > >>>>>>>> All true. I asked to try -hypervisor only to verify where we loose > > >>>>>>>> performance. Since you get good result with it frequent access to > > >>>>>>>> PM timer is probably the reason. I do not recommend using > > >>>>>>>> -hypervisor for production! > > >>>>>>>> > > >>>>>>>>> @gleb: do you know whats the state of in-kernel hyper-v timers? > > >>>>>>>> > > >>>>>>>> Vadim is working on it. I'll let him answer. > > >>>>>>> > > >>>>>>> It would be nice to have synthetic timers supported. But, at the > > >>>>>>> moment, I'm only researching this feature. > > >>>>>> > > >>>>>> So it will take months at least? > > >>>>> > > >>>>> I would say weeks. > > >>>> > > >>>> Is there a way, we could contribute and help you with this? > > >>> > > >>> Hi Peter, > > >>> You are welcome to add an appropriate handler. > > >> > > >> I think Vadim refers to this HV MSR > > >> http://msdn.microsoft.com/en-us/library/windows/hardware/ff542633%28v=vs > > >> .85 %29.aspx > > > > > > This one is pretty simple to support. Please see attachments for more > > > details. I was thinking about synthetic timers > > > http://msdn.microsoft.com/en- > > > us/library/windows/hardware/ff542758(v=vs.85).aspx > > > > is this what microsoft qpc uses as clocksource in hyper-v? > Yes, it should be enough for Win7 / W2K8R2. To clarify the thing that microsoft qpc uses is what is implemented by the patch Vadim attached to his previous email. But I believe that additional qemu patch is needed for Windows to actually use it. -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
