From: Stefan Priebe - Profihost AG <s.priebe@profihost.ag>
To: "ceph-devel@vger.kernel.org" <ceph-devel@vger.kernel.org>
Subject: Re: extreme ceph-osd cpu load for rand. 4k write
Date: Thu, 08 Nov 2012 15:58:00 +0100 [thread overview]
Message-ID: <509BC878.3090804@profihost.ag> (raw)
In-Reply-To: <509AC772.5010606@profihost.ag>
Is there any way to find out why a ceph-osd process takes around 10
times more load on rand 4k writes than on 4k reads?
Stefan
Am 07.11.2012 21:41, schrieb Stefan Priebe:
> Hello list,
>
> whiling benchmarking i was wondering, why the ceph-osd load is so
> extreme high while having random 4k write i/o.
>
> Here an example while benchmarking:
>
> random 4k write: 16.000 iop/s 180% CPU Load in top from EACH ceph-osd
> process
>
> random 4k read: 16.000 iop/s 19% CPU Load in top from EACH ceph-osd process
>
> seq 4M write: 800MB/s 14% CPU Load in top from EACH ceph-osd process
>
> seq 4M read: 1600MB/s 9% CPU Load in top from EACH ceph-osd process
>
> I can't understand why in this single case the load is so EXTREMELY high.
>
> Greets
> Stefan
next prev parent reply other threads:[~2012-11-08 14:58 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-07 20:41 extreme ceph-osd cpu load for rand. 4k write Stefan Priebe
2012-11-08 14:58 ` Stefan Priebe - Profihost AG [this message]
2012-11-08 15:01 ` Sage Weil
2012-11-08 15:45 ` Stefan Priebe - Profihost AG
2012-11-08 16:06 ` Mark Nelson
2012-11-08 21:27 ` Stefan Priebe
2012-11-08 21:50 ` Josh Durgin
2012-11-08 21:58 ` Mark Nelson
2012-11-08 22:06 ` Stefan Priebe
2012-11-08 22:31 ` Stefan Priebe
2012-11-09 10:09 ` Stefan Priebe - Profihost AG
2012-11-09 10:21 ` Stefan Priebe - Profihost AG
2012-11-09 21:21 ` Samuel Just
2012-11-09 21:34 ` Stefan Priebe - Profihost AG
2012-11-10 20:36 ` Samuel Just
2012-11-10 20:37 ` Samuel Just
2012-11-10 20:43 ` Stefan Priebe
2012-11-10 20:42 ` Stefan Priebe
2012-11-08 15:01 ` Mark Nelson
2012-11-08 15:45 ` Stefan Priebe - Profihost AG
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