From mboxrd@z Thu Jan  1 00:00:00 1970
From: Peter Lieven <pl@dlh.net>
Subject: Re: performance trouble
Date: Wed, 21 Mar 2012 18:31:02 +0100
Message-ID: <4F6A1056.1020904@dlh.net>
References: <20120217140107.GA26955@nfs-rbx.ovh.net> <20120219091315.GA10038@redhat.com> <20120222163356.GE26955@nfs-rbx.ovh.net> <20120223083807.GA17505@redhat.com> <20120316101331.GM12293@nfs-rbx.ovh.net> <20120319105134.GA27928@redhat.com> <20120320093220.GS12293@nfs-rbx.ovh.net> <20120320094541.GH22368@redhat.com> <20120320111839.GT12293@nfs-rbx.ovh.net> <20120320123821.GL22368@redhat.com> <20120321111001.GV12293@nfs-rbx.ovh.net>
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Cc: Gleb Natapov <gleb@redhat.com>, Avi Kivity <avi@redhat.com>,
	kvm@vger.kernel.org, Vadim Rozenfeld <vrozenfe@redhat.com>
To: David Cure <kvm@cure.nom.fr>
Return-path: <kvm-owner@vger.kernel.org>
Received: from ssl.dlh.net ([91.198.192.8]:39749 "EHLO ssl.dlh.net"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1758529Ab2CURbF (ORCPT <rfc822;kvm@vger.kernel.org>);
	Wed, 21 Mar 2012 13:31:05 -0400
In-Reply-To: <20120321111001.GV12293@nfs-rbx.ovh.net>
Sender: kvm-owner@vger.kernel.org
List-ID: <kvm.vger.kernel.org>

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-cpu.txt.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.

@gleb: do you know whats the state of in-kernel hyper-v timers?

peter

> 	David.
> --
> To unsubscribe from this list: send the line "unsubscribe kvm" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html