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.txt.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. > > What do the others think, would it be feasible to make a proper in-kernel > pmtimer solution in the meantime. > > I think Windows guest performance is very important for the success of KVM. > > Peter > > >>> peter > >>> > >>>> David. > >>>> > >>>> -- > >>>> 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 > >> > >> -- > >> > >> 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
