From: Alexandre DERUMIER <aderumier@odiso.com>
To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: josh durgin <josh.durgin@inktank.com>,
qemu-devel <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] is it possible to use a disk with multiple iothreads ?
Date: Mon, 27 Oct 2014 15:13:11 +0100 (CET) [thread overview]
Message-ID: <33a4db31-a5e2-4bfc-b73b-c0e7d3023542@mailpro> (raw)
In-Reply-To: <20141027131958.GC15071@stefanha-thinkpad.redhat.com>
[-- Attachment #1: Type: text/plain, Size: 3813 bytes --]
>>That's very interesting! Please keep Josh and me in CC when you want to
>>discuss the results.
Here the aggregate results (perf report details attached in this mail)
+ 33,02% 3974368751 kvm [kernel.kallsyms]
+ 23,66% 2847206635 kvm libc-2.13.so
+ 18,79% 2262052133 kvm librados.so.2.0.0
+ 11,04% 1328581527 kvm librbd.so.1.0.0
+ 5,87% 706713737 kvm libpthread-2.13.so
+ 3,75% 451690142 kvm kvm
+ 2,74% 329457334 kvm libstdc++.so.6.0.17
+ 0,51% 61519664 kvm [vdso] + 0,42% 50000089 kvm libglib-2.0.so.0.3200.4 + 0,15% 18119658 kvm libm-2.13.so + 0,05% 5705776 kvm librt-2.13.so + 0,00% 356625 kvm libz.so.1.2.7
>> 23,66% 2847206635 kvm libc-2.13.so
This one is mostly malloc,free,...
I see almost same results using fio with rbdengine on the host (outside the kvm process).
So I think they are all mostly related to librbd.
----- Mail original -----
De: "Stefan Hajnoczi" <stefanha@redhat.com>
À: "Alexandre DERUMIER" <aderumier@odiso.com>
Cc: "qemu-devel" <qemu-devel@nongnu.org>, "josh durgin" <josh.durgin@inktank.com>
Envoyé: Lundi 27 Octobre 2014 14:19:58
Objet: Re: is it possible to use a disk with multiple iothreads ?
On Fri, Oct 24, 2014 at 03:39:52PM +0200, Alexandre DERUMIER wrote:
> >>Regarding Ceph, do you know why it burns a lot of CPU?
>
> I'm currently doing some perfs to find why is so huge.
>
> One thing is that qemu+ qemu rbd block driver + librbd seem to use 2-3x more cpu, than passing krbd /dev/rbd0 from host to qemu.
> Don't known yet if the problem is librbd or qemu rbd block driver.
That's very interesting! Please keep Josh and me in CC when you want to
discuss the results.
Stefan
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next prev parent reply other threads:[~2014-10-27 14:13 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <391d6bb1-e0ad-49ea-afdc-fff462081f24@mailpro>
2014-10-23 18:26 ` [Qemu-devel] is it possible to use a disk with multiple iothreads ? Alexandre DERUMIER
2014-10-24 9:04 ` Stefan Hajnoczi
2014-10-24 13:39 ` Alexandre DERUMIER
2014-10-27 13:19 ` Stefan Hajnoczi
2014-10-27 14:13 ` Alexandre DERUMIER [this message]
2014-10-27 14:47 ` Paolo Bonzini
2014-10-27 16:42 ` Alexandre DERUMIER
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