From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Nelson Subject: Re: OSD Hardware questions Date: Thu, 28 Jun 2012 09:38:32 -0500 Message-ID: <4FEC6C68.2030307@inktank.com> References: <4FEB04CC.4050008@profihost.ag> <4FEB10DA.7010206@inktank.com> <4FEB2310.9080801@profihost.ag> <4FEB26A7.4070507@profihost.ag> <4FEB2E07.6010402@inktank.com> <4FEC5A4E.1090209@profihost.ag> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-qc0-f174.google.com ([209.85.216.174]:47765 "EHLO mail-qc0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752403Ab2F1Oiw (ORCPT ); Thu, 28 Jun 2012 10:38:52 -0400 Received: by qcro28 with SMTP id o28so1161096qcr.19 for ; Thu, 28 Jun 2012 07:38:51 -0700 (PDT) In-Reply-To: <4FEC5A4E.1090209@profihost.ag> Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Stefan Priebe - Profihost AG Cc: Gregory Farnum , "ceph-devel@vger.kernel.org" On 06/28/2012 08:21 AM, Stefan Priebe - Profihost AG wrote: > Am 27.06.2012 18:00, schrieb Mark Nelson: >> On 06/27/2012 10:28 AM, Stefan Priebe wrote: >>>> Well, as we said, 1GHz/OSD was a WAG (wild-ass guess), but 3.6GHz+/OSD >>>> is farther outside of that range than I would have expected. It might >>>> just be a consequence of using SSDs, since they can sustain so much >>>> more >>>> throughput. >>> >>> Sure it was just so much away from 1Ghz that i wanted to ask. >>> >>>> What is the cluster doing when you see those CPU usage numbers? >>> random write I/O from one KVM. 14k I/Ops with random 4k writes. >>> >>> Stefan >> >> I think I was seeing about 80-85% CPU utilization with 5 SSD OSDs on our >> 6-core AMD nodes, but I was just doing sequential writes with rados >> bench. > > While doing sequential writes i see pretty low CPU usage. Random writes > is the problem. > > Stefan It would be interesting to see where all your CPU time is being spent. What benchmark are you using to do the random writes? Mark