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.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.
> >
> > 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
--
Gleb.
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