From: Stefan Priebe - Profihost AG <s.priebe@profihost.ag>
To: Sage Weil <sage@inktank.com>
Cc: "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 16:45:15 +0100 [thread overview]
Message-ID: <509BD38B.8090200@profihost.ag> (raw)
In-Reply-To: <alpine.DEB.2.00.1211080658560.11845@cobra.newdream.net>
Am 08.11.2012 16:01, schrieb Sage Weil:
> On Thu, 8 Nov 2012, Stefan Priebe - Profihost AG wrote:
>> 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?
>
> Something like perf or oprofile is probably your best bet. perf can be
> tedious to deploy, depending on where your kernel is coming from.
> oprofile seems to be deprecated, although I've had good results with it in
> the past.
I've recorded 10s with perf - it is now a 300MB perf.data file. Sadly
i've no idea what todo with it next.
> would love to see where the CPU is spending most of it's time. This is
> on current master?
Yes
> I expect there are still some low-hanging fruit that
> can bring CPU utilization down (or even boost iops).
Would be great to find them.
Stefan
next prev parent reply other threads:[~2012-11-08 15:45 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
2012-11-08 15:01 ` Sage Weil
2012-11-08 15:45 ` Stefan Priebe - Profihost AG [this message]
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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