On Tue, Mar 27, 2012 at 02:28:04PM +0200, Peter Lieven wrote: > On 27.03.2012 14:26, Gleb Natapov wrote: > >On Tue, Mar 27, 2012 at 02:20:23PM +0200, Peter Lieven wrote: > >>On 27.03.2012 12:00, Gleb Natapov wrote: > >>>On Tue, Mar 27, 2012 at 11:26:29AM +0200, 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? > >>>> > >>>>the stuff you send yesterday is for qemu, right? would > >>>>it be possible to use it in qemu-kvm also? > >>>> > >>>No, they are for kernel. > >>i meant the qemu.diff file. > >> > >Yes, I missed the second attachment. > > > >>if i understand correctly i have to pass -cpu host,+hv_refcnt to qemu? > >> > >Looks like it. > ok, so it would be interesting if it helps to avoid the pmtimer reads > we observed earlier. right? > Yes. -- 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
