On Thu, Nov 8, 2012 at 7:53 PM, Alexandre DERUMIER <aderumier@xxxxxxxxx> wrote: >>>So it is a problem of KVM which let's the processes jump between cores a >>>lot. > > maybe numad from redhat can help ? > http://fedoraproject.org/wiki/Features/numad > > It's try to keep process on same numa node and I think it's also doing some dynamic pinning. Numad keeps only memory chunks on the preferred node, cpu pinning, which is a primary goal there, should be done separately via libvirt or manually for qemu process via cpuset(libvirt does pinning via taskset and seems that it is broken at least in debian wheezy - even affinity mask is set for qemu process, load spreads all over numa node, including cpus outside the set). > > ----- Mail original ----- > > De: "Stefan Priebe - Profihost AG" <s.priebe@xxxxxxxxxxxx> > À: "Mark Nelson" <mark.nelson@xxxxxxxxxxx> > Cc: "Joao Eduardo Luis" <joao.luis@xxxxxxxxxxx>, ceph-devel@xxxxxxxxxxxxxxx > Envoyé: Jeudi 8 Novembre 2012 16:14:32 > Objet: Re: less cores more iops / speed > > Am 08.11.2012 14:19, schrieb Mark Nelson: >> On 11/08/2012 02:45 AM, Stefan Priebe - Profihost AG wrote: >>> Am 08.11.2012 01:59, schrieb Mark Nelson: >>>> There's also the context switching overhead. It'd be interesting to >>>> know how much the writer processes were shifting around on cores. >>> What do you mean by that? I'm talking about the KVM guest not about the >>> ceph nodes. >> >> in this case, is fio bouncing around between cores? > > Thanks you're correct. If i bind fio to two cores on a 8 core VM it runs > with 16.000 iops. > > So it is a problem of KVM which let's the processes jump between cores a > lot. > > Greets, > Stefan > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
