On Tuesday, March 27, 2012 04:06:13 PM Peter Lieven wrote: > On 27.03.2012 14:29, Gleb Natapov wrote: > > 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-1v > >>>>>>>>>>>>>>>>>>>> cpu-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/ff542 > >>>>>>>>>>>> 633%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. > > first feedback: performance seems to be amazing. i cannot confirm that > it breaks hv_spinlocks, hv_vapic and hv_relaxed. > why did you assume this? I didn't mean that hv_refcnt will break any other hyper-v features. I just want to say that turning hv_refcnt on (as any other hv_ option) will crash Win8 on boot-up.
Cheers, Vadim. > > no more pmtimer reads. i can now almost fully utililizy a 1GBit > interface with a file transfer while there was not one > cpu core fully utilized as observed with pmtimer. some live migration > tests revealed that it did not crash even under load. > > @vadim: i think we need a proper patch for the others to test this ;-) > > what i observed: is it right, that HV_X64_MSR_TIME_REF_COUNT is missing > in msrs_to_save[] in x86/x86.c of the kernel module? > > thanks for you help, > peter > > > -- > > > > Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
