From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: slow guest performance with build load, looking for ideas Date: Thu, 02 Jul 2009 12:41:01 +0300 Message-ID: <4A4C80AD.7010204@redhat.com> References: <20090612210443.GA21840@sgi.com> <4A34C3D2.9020009@redhat.com> <20090618230744.GA19307@sgi.com> <4A477B8C.2010502@redhat.com> <20090628190500.GA7347@sgi.com> <4A47E06A.7040700@redhat.com> <20090701214128.GA1380@sgi.com> <4A4C4A28.1060105@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org To: Erik Jacobson Return-path: Received: from mx2.redhat.com ([66.187.237.31]:60951 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753313AbZGBJjI (ORCPT ); Thu, 2 Jul 2009 05:39:08 -0400 In-Reply-To: <4A4C4A28.1060105@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 07/02/2009 08:48 AM, Avi Kivity wrote: >> HOST time (make -j12&& make -j12 modules) with no guest running >> ---------------------------------------------------------------- >> real 6m50.936s >> user 29m12.051s >> sys 5m50.867s >> > > 35 minutes cpu run on 7 minutes real time, so scaling 1:7. User time > almost the same, system time different but not enough to account for > the large difference in run time. > > I'm due to get my own Nehalem next week, I'll try to reproduce your > results here. > I reproduced this on a 2x4 barcelona, I get 6.6x scaling on the guest compared to your 7.2x on the host. This is with a kvm.git host kernel. Once thing that changed is an improvement in cfq with multiple threads; try setting the host io scheduler for /dev/sdb to deadline (together with dropping -usbdevice tablet). -- error compiling committee.c: too many arguments to function