Could be one of the bugs fixed in guest drivers since 2.6.32. For example, 39d321577405e8e269fd238b278aaf2425fa788a ? Does it help if you try a more recent guest?
On Thu, Mar 14, 2013 at 11:43:30AM +0100, Alexandre DERUMIER wrote: > I don't think it's fixed in 1.3 or 1.4, some proxmox users have reported > again this bug with guest kernel 2.6.32. (proxmox host is rhel 6.3 kernel + > qemu 1.4) > > > > ----- Mail original ----- > > De: "Davide Guerri" <d.gue...@unidata.it> > À: "Alexandre DERUMIER" <aderum...@odiso.com> > Cc: "Peter Lieven" <p...@dlhnet.de>, "Michael S. Tsirkin" <m...@redhat.com>, > "Stefan Hajnoczi" <stefa...@gmail.com>, qemu-devel@nongnu.org, "Jan Kiszka" > <jan.kis...@web.de>, "Peter Lieven" <lieven-li...@dlhnet.de>, "Dietmar > Maurer" <diet...@proxmox.com> > Envoyé: Jeudi 14 Mars 2013 10:22:22 > Objet: Re: [Qemu-devel] slow virtio network with vhost=on and multiple cores > > I'd like to reopen this thread because this problem is still here and it's > really annoying. > Another possible work-around is to pin the virtio nic irq to one virtual CPU > (with /proc/smp_affinity) but (of course) this is still sub-optimal. > > Here are some graphs showing the performance of a heavy loaded machine after > and before a live migration from KVM-1.0 to KVM-1.2. > Host is a Ubuntu 12.10 Kernel 3.5, guest is a Ubuntu 10.04.4 LTS Kernel 2.6.32 > > History > ------- > CPU time: > http://s1299.beta.photobucket.com/user/dguerri/media/CPU-10days_zps4a088ff0.png.html > CPU Load: > http://s1299.beta.photobucket.com/user/dguerri/media/Load-10days_zpsff27f212.png.html > NET pps: > http://s1299.beta.photobucket.com/user/dguerri/media/pps-10days_zps003dd039.png.html > NET Mbps: > http://s1299.beta.photobucket.com/user/dguerri/media/Mbps-10days_zpsfc3cba8c.png.html > > Current > ------- > CPU time: > http://s1299.beta.photobucket.com/user/dguerri/media/CPU-2days_zpsd362cac6.png.html > CPU Load: > http://s1299.beta.photobucket.com/user/dguerri/media/load-2days_zpsd4b7b50d.png.html > NET pps: > http://s1299.beta.photobucket.com/user/dguerri/media/pps-2days_zps8f5458c9.png.html > NET Mbps: > http://s1299.beta.photobucket.com/user/dguerri/media/Mbps-2days_zps299338b9.png.html > > Red arrows indicate the kvm version change. > Black arrows indicate when I "pinned" the virtio NIC IRQ to only one CPU > (that machine has 2 virtual cores). > As can be seen the performance penalty is rather high: that machine was > almost unusable! > > Does version 1.3 fixes this issue? > > Could someone with the required knowledge look into this, please? > Please, this is a very nasty bug because I guess I'm not the only one who is > unable to upgrade all the machines with a (not-so) old kernel... :) > > Thanks! > > Davide Guerri. > > > > > On 09/dic/2012, at 19:38, Alexandre DERUMIER <aderum...@odiso.com> wrote: > > >>> Have you had any further progress on this regression/problem? > > > > Hi Peter, > > I didn't re-tested myself, > > but a proxmox user who's have the problem with qemu-kvm 1.2, with windows > > guest and linux guest, > > don't have the problem anymore with qemu 1.3. > > > > http://forum.proxmox.com/threads/12157-Win2003R2-in-KVM-VM-is-slow-in-PVE-2-2-when-multiply-CPU-cores-allowed > > > > I'll try to redone test myself this week > > > > Regards, > > > > Alexandre > > > > ----- Mail original ----- > > > > De: "Peter Lieven" <p...@dlhnet.de> > > À: "Alexandre DERUMIER" <aderum...@odiso.com> > > Cc: "Dietmar Maurer" <diet...@proxmox.com>, "Stefan Hajnoczi" > > <stefa...@gmail.com>, "Jan Kiszka" <jan.kis...@web.de>, > > qemu-devel@nongnu.org, "Michael S. Tsirkin" <m...@redhat.com>, "Peter > > Lieven" <lieven-li...@dlhnet.de> > > Envoyé: Lundi 3 Décembre 2012 12:23:11 > > Objet: Re: [Qemu-devel] slow virtio network with vhost=on and multiple cores > > > > > > Am 16.11.2012 um 12:00 schrieb Alexandre DERUMIER <aderum...@odiso.com>: > > > >>>> While trying to reproduce the bug, we just detected that it depends on > >>>> the hardware (mainboard) you run on. > >>>> > >>>> Sigh :-/ > >> > >> Hi, > >> > >> I can reproduce the bug on all my dell servers,differents generation (R710 > >> (intel),R815 (amd), 2950 (intel). > >> > >> They all use broadcom bnx2 network card (don't know if it can be related) > >> > >> host kernel : rhel 63 with 2.6.32 kernel > >> > >> guest kernel : 2.6.32 (debian squeeze, ubuntu). > >> > >> No problem with guest kernel 3.2 > > > > Have you had any further progress on this regression/problem? > > > > Thanks, > > Peter > > > >> > >> > >> > >> > >> ----- Mail original ----- > >> > >> De: "Dietmar Maurer" <diet...@proxmox.com> > >> À: "Peter Lieven" <lieven-li...@dlhnet.de> > >> Cc: "Stefan Hajnoczi" <stefa...@gmail.com>, "Peter Lieven" > >> <p...@dlhnet.de>, "Jan Kiszka" <jan.kis...@web.de>, qemu-devel@nongnu.org, > >> "Michael S. Tsirkin" <m...@redhat.com> > >> Envoyé: Vendredi 16 Novembre 2012 11:44:26 > >> Objet: Re: [Qemu-devel] slow virtio network with vhost=on and multiple > >> cores > >> > >>>> I only tested with RHEL6.3 kernel on host. > >>> > >>> can you check if there is a difference on interrupt delivery between those > >>> two? > >>> > >>> cat /proc/interrupts should be sufficient after some traffic has flown. > >> > >> While trying to reproduce the bug, we just detected that it depends on the > >> hardware (mainboard) you run on. > >> > >> Sigh :-/ > > > >