On Tuesday, March 27, 2012 11:26:29 AM Peter Lieven wrote:
> On 27.03.2012 11:23, Vadim Rozenfeld wrote:
> > On Tuesday, March 27, 2012 10:56:05 AM Gleb Natapov wrote:
> >> 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-cp
> >>>>>>>>>>>>>> u.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%28
> >>>>>> v=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.
> >
> > You are right.
> > bits 1 and 9 must be set to on in leaf 0x40000003 and HPET
> > should be completely removed from ACPI.
>
> could you advise how to do this and/or make a patch?
Gleb mentioned that it properly handled in upstream,
otherwise just comment the entire HPET section in
acpi-dsdt.dsl file.
>
> the stuff you send yesterday is for qemu, right? would
> it be possible to use it in qemu-kvm also?
Yes, but don't forget about kvm patch as well.
>
> peter
>
> >> --
> >>
> >> Gleb.
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