From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:45031) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1T20mq-0000Q3-Js for qemu-devel@nongnu.org; Thu, 16 Aug 2012 10:11:08 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1T20mo-0003r2-TC for qemu-devel@nongnu.org; Thu, 16 Aug 2012 10:11:00 -0400 Received: from paradis.irqsave.net ([109.190.18.76]:39582) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1T20mo-0003qU-G6 for qemu-devel@nongnu.org; Thu, 16 Aug 2012 10:10:58 -0400 Date: Thu, 16 Aug 2012 16:10:53 +0200 From: =?iso-8859-1?Q?Beno=EEt?= Canet Message-ID: <20120816141052.GB2080@irqsave.net> References: <20120816104727.GA17166@alpha.arachsys.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20120816104727.GA17166@alpha.arachsys.com> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] Windows slow boot: contractor wanted List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Richard Davies Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org Le Thursday 16 Aug 2012 =E0 11:47:27 (+0100), Richard Davies a =E9crit : > Hi, >=20 > We run a cloud hosting provider using qemu-kvm 1.1, and are keen to fin= d a > contractor to track down and fix problems we have with large memory Win= dows > guests booting very slowly - they can take several hours. >=20 > We previously reported these problems in July (copied below) and they a= re > still present with Linux kernel 3.5.1 and qemu-kvm 1.1.1. >=20 > This is a serious issue for us which is causing significant pain to our > larger Windows VM customers when their servers are offline for many hou= rs > during boot. >=20 > If anyone knowledgeable in the area would be interested in being paid t= o > work on this, or if you know someone who might be, I would be delighted= to > hear from you. >=20 > Cheers, >=20 > Richard. >=20 >=20 > =3D=3D=3D=3D=3D Previous bug report >=20 > http://marc.info/?l=3Dqemu-devel&m=3D134304194329745 >=20 >=20 > We have been experiencing this problem for a while now too, using qemu-= kvm > (currently at 1.1.1). >=20 > Unfortunately, hv_relaxed doesn't seem to fix it. The following command= line > produces the issue: >=20 > qemu-kvm -nodefaults -m 4096 -smp 8 -cpu host,hv_relaxed -vga cirrus -u= sbdevice tablet -vnc :99 -monitor stdio -hda test.img >=20 > The hardware consists of dual AMD Opteron 6128 processors (16 cores in > total) and 64GB of memory. This command line was tested on kernel 3.1.4= .=20 >=20 > I've also tested with -no-hpet. >=20 > What I have seen is much as described: the memory fills out slowly, and= top > on the host will show the process using 100% on all allocated CPU cores= . The > most extreme case was a machine which took something between 6 and 8 ho= urs > to boot. >=20 > This seems to be related to the assigned memory, as described, but also= the > number of processor cores (which makes sense if we believe it's a timin= g > issue?). I have seen slow-booting guests improved by switching down to = a > single or even two cores. >=20 > Matthew, I agree that this seems to be linked to the number of VMs runn= ing - > in fact, shutting down other VMs on a dedicated test host caused the ma= chine > to start booting at a normal speed (with no reboot required). >=20 > However, the level of contention is never such that this could be expla= ined > by the host simply being overcommitted. >=20 > If it helps anyone, there's an image of the hard drive I've been using = to > test at: >=20 > http://46.20.114.253/ >=20 > It's 5G of gzip file containing a fairly standard Windows 2008 trial > installation. Since it's in the trial period, anyone who wants to use i= t may > have to re-arm the trial: http://support.microsoft.com/kb/948472 >=20 > Please let me know if I can provide any more information, or test anyth= ing. For info the image boot pretty fast with qemu-kvm 1.1.1 and a 3.2.0-29 ub= untu kernel on a core i7 with these parameters. Beno=EEt >=20 > Best wishes, >=20 > Owen Tuz >=20