From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Lieven Subject: Re: performance trouble Date: Tue, 27 Mar 2012 14:20:23 +0200 Message-ID: <4F71B087.8060008@dlh.net> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Vadim Rozenfeld , David Cure , Avi Kivity , kvm@vger.kernel.org To: Gleb Natapov Return-path: Received: from ssl.dlh.net ([91.198.192.8]:33081 "EHLO ssl.dlh.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752100Ab2C0MU0 (ORCPT ); Tue, 27 Mar 2012 08:20:26 -0400 In-Reply-To: <20120327100034.GT22368@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: 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. if i understand correctly i have to pass -cpu host,+hv_refcnt to qemu? peter > -- > Gleb.