From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756935AbZEALLf (ORCPT ); Fri, 1 May 2009 07:11:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753912AbZEALL1 (ORCPT ); Fri, 1 May 2009 07:11:27 -0400 Received: from mail-bw0-f163.google.com ([209.85.218.163]:41884 "EHLO mail-bw0-f163.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753645AbZEALL0 (ORCPT ); Fri, 1 May 2009 07:11:26 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=Z4ZdLeQHx6KQejjk+6jSnguqrkhbOMApDd3yaAxA3BgkIcfNVvgNMzjVVrdkc8Jn/6 j1b+5AedLGeBzWlAIe29P9EzkZ/1GDOhW4SVPJb1TX5iLJLqzIoYR5ordCTqSmNmNuWY fpVUjbt6LTNWJFlG6HXmayT0xhd9Ss7xrzulw= Date: Fri, 1 May 2009 13:11:22 +0200 From: Andrea Righi To: "Alan D. Brunelle" Cc: Paul Menage , Balbir Singh , Gui Jianfeng , KAMEZAWA Hiroyuki , agk@sourceware.org, akpm@linux-foundation.org, axboe@kernel.dk, baramsori72@gmail.com, Carl Henrik Lunde , dave@linux.vnet.ibm.com, Divyesh Shah , eric.rannaud@gmail.com, fernando@oss.ntt.co.jp, Hirokazu Takahashi , Li Zefan , matt@bluehost.com, dradford@bluehost.com, ngupta@google.com, randy.dunlap@oracle.com, roberto@unbit.it, Ryo Tsuruta , Satoshi UCHIDA , subrata@linux.vnet.ibm.com, yoshikawa.takuya@oss.ntt.co.jp, containers@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/9] cgroup: io-throttle controller (v13) Message-ID: <20090501111121.GA25964@linux> References: <1239740480-28125-1-git-send-email-righi.andrea@gmail.com> <49F9A5BA.9030100@hp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <49F9A5BA.9030100@hp.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 30, 2009 at 09:20:58AM -0400, Alan D. Brunelle wrote: > Hi Andrea - Hi Alan, > > FYI: I ran a simple test using this code to try and gauge the overhead > incurred by enabling this technology. Using a single 400GB volume split > into two 200GB partitions I ran two processes in parallel performing a > mkfs (ext2) on each partition. First w/out cgroup io-throttle and then > with it enabled (with each task having throttling enabled to > 400MB/second (much, much more than the device is actually capable of > doing)). The idea here is to see the base overhead of just having the > io-throttle code in the paths. Interesting. I've never explicitly measured the actual overhead of the io-throttle infrastructure, I'll add a similar test to the io-throttle testcase. > > Doing 30 runs of each (w/out & w/ io-throttle enabled) shows very little > difference (time in seconds) > > w/out: min=80.196 avg=80.585 max=81.030 sdev=0.215 spread=0.834 > with: min=80.402 avg=80.836 max=81.623 sdev=0.327 spread=1.221 > > So only around 0.3% overhead - and that may not be conclusive with the > standard deviations seen. You should see less overhead with reads respect to a pure write workload, because with reads we don't need to check if the IO request occurs in a different IO context. And things should be improved with v16-rc1 (http://download.systemimager.org/~arighi/linux/patches/io-throttle/cgroup-io-throttle-v16-rc1.patch). So, it would be also interesting to analyse the overhead of a read stream compared to a write stream, as well a comparison of random reads/writes. I'll do that in my next benchmarking session. > > -- > > FYI: The test was run on 2.6.30-rc1+your patches on a 16-way x86_64 box > (128GB RAM) plus a single FC volume off of a 1Gb FC RAID controller. > > Regards, > Alan D. Brunelle > Hewlett-Packard Thanks for posting these results, -Andrea