From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:46279) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QzINO-0004bN-R8 for qemu-devel@nongnu.org; Thu, 01 Sep 2011 21:16:59 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QzINN-0007W1-Fn for qemu-devel@nongnu.org; Thu, 01 Sep 2011 21:16:58 -0400 Received: from [222.73.24.84] (port=54326 helo=song.cn.fujitsu.com) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QzINM-0007Vv-Sb for qemu-devel@nongnu.org; Thu, 01 Sep 2011 21:16:57 -0400 Message-ID: <4E602E8B.6010900@cn.fujitsu.com> Date: Fri, 02 Sep 2011 09:16:59 +0800 From: Gui Jianfeng MIME-Version: 1.0 References: <20110901050531.GB17963@f15.cn.ibm.com> <20110901081149.GB14245@stefanha-thinkpad.localdomain> In-Reply-To: <20110901081149.GB14245@stefanha-thinkpad.localdomain> Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-8859-1 Subject: Re: [Qemu-devel] [RFC] block I/O throttling: how to enable in libvirt List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi , Zhi Yong Wu Cc: libvir-list@redhat.com, hutao@cn.fujitsu.com, qemu-devel@nongnu.org, zwu.kernel@gmail.com, agl@us.ibm.com On 2011-9-1 16:11, Stefan Hajnoczi wrote: > On Thu, Sep 01, 2011 at 01:05:31PM +0800, Zhi Yong Wu wrote: >> On Wed, Aug 31, 2011 at 08:18:19AM +0100, Stefan Hajnoczi wrote: >>> On Tue, Aug 30, 2011 at 2:46 PM, Adam Litke wrote: >>>> On Tue, Aug 30, 2011 at 09:53:33AM +0100, Stefan Hajnoczi wrote: >>>>> I/O throttling can be applied independently to each -drive attached to >>>>> a guest and supports throughput/iops limits. For more information on >>>>> this QEMU feature and a comparison with blkio-controller, see Ryan >>>>> Harper's KVM Forum 2011 presentation: >>>> >>>>> http://www.linux-kvm.org/wiki/images/7/72/2011-forum-keep-a-limit-on-it-io-throttling-in-qemu.pdf >>>> >>>> From the presentation, it seems that both the cgroups method the the qemu method >>>> offer comparable control (assuming a block device) so it might possible to apply >>>> either method from the same API in a transparent manner. Am I correct or are we >>>> suggesting that the Qemu throttling approach should always be used for Qemu >>>> domains? >>> >>> QEMU I/O throttling does not provide a proportional share mechanism. >>> So you cannot assign weights to VMs and let them receive a fraction of >>> the available disk time. That is only supported by cgroups >>> blkio-controller because it requires a global view which QEMU does not >>> have. >>> >>> So I think the two are complementary: >>> >>> If proportional share should be used on a host block device, use >>> cgroups blkio-controller. >>> Otherwise use QEMU I/O throttling. >> Stefan, >> >> Do you agree with introducing one new libvirt command blkiothrottle now? >> If so, i will work on the code draft to make it work. > > No, I think that the blkiotune command should be extended to support > QEMU I/O throttling. This is not new functionality, we already have > cgroups blkio-controller support today. Therefore I think it makes > sense to keep a unified interface instead of adding a new command. Agreed. Proportional controlling interfaces and throttling interfaces are all the same cgroup subsystem. So Just extend blkiotune to add new options to support throttling tuning. Thanks, Gui > > Stefan > >