>>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. ----- 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
