From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gleb Natapov Subject: Re: performance trouble Date: Tue, 27 Mar 2012 14:26:46 +0200 Message-ID: <20120327122645.GW22368@redhat.com> References: <20120222163356.GE26955@nfs-rbx.ovh.net> <201203262211.44284.vrozenfe@redhat.com> <20120327085604.GQ22368@redhat.com> <201203271123.33524.vrozenfe@redhat.com> <4F7187C5.4080607@dlh.net> <20120327100034.GT22368@redhat.com> <4F71B087.8060008@dlh.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Vadim Rozenfeld , David Cure , Avi Kivity , kvm@vger.kernel.org To: Peter Lieven Return-path: Received: from mx1.redhat.com ([209.132.183.28]:24417 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751972Ab2C0M0w (ORCPT ); Tue, 27 Mar 2012 08:26:52 -0400 Content-Disposition: inline In-Reply-To: <4F71B087.8060008@dlh.net> Sender: kvm-owner@vger.kernel.org List-ID: 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 > >>>>>>>>>>>>>>>>>to cpu definition in XML and check command line. > >>>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>> ok I try this but I can't use to map the > >>>>>>>>>>>>>>>> host cpu > >>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>>(my libvirt is 0.9.8) so I use : > >>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>> Opteron_G3 > >>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>> > >>>>>>>>>>>>>>>> (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. -- Gleb.