On Fri, Sep 02, 2011 at 09:16:59AM +0800, Gui Jianfeng wrote:
Message-ID: <4E602E8B.6010900@cn.fujitsu.com> Date: Fri, 02 Sep 2011 09:16:59 +0800 From: Gui Jianfeng <guijianfeng@cn.fujitsu.com> User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:6.0) Gecko/20110812 Thunderbird/6.0 MIME-Version: 1.0 To: Stefan Hajnoczi <stefanha@gmail.com>, Zhi Yong Wu <wuzhy@linux.vnet.ibm.com> References: <20110901050531.GB17963@f15.cn.ibm.com> <20110901081149.GB14245@stefanha-thinkpad.localdomain> In-Reply-To: <20110901081149.GB14245@stefanha-thinkpad.localdomain> X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2011-09-02 09:15:49, Serialize by Router on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2011-09-02 09:15:52, Serialize complete at 2011-09-02 09:15:52 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-8859-1 X-detected-operating-system: by eggs.gnu.org: FreeBSD 6.x (1) X-Received-From: 222.73.24.84 Cc: libvir-list@redhat.com, hutao@cn.fujitsu.com, qemu-devel@nongnu.org, zwu.kernel@gmail.com, agl@us.ibm.com Subject: Re: [Qemu-devel] [RFC] block I/O throttling: how to enable in libvirt X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: <qemu-devel.nongnu.org> List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>, <mailto:qemu-devel-request@nongnu.org?subject=unsubscribe> List-Archive: </archive/html/qemu-devel> List-Post: <mailto:qemu-devel@nongnu.org> List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help> List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>, <mailto:qemu-devel-request@nongnu.org?subject=subscribe> X-Mailman-Copy: yes Errors-To: qemu-devel-bounces+wuzhy=linux.vnet.ibm.com@nongnu.org Sender: qemu-devel-bounces+wuzhy=linux.vnet.ibm.com@nongnu.org X-Brightmail-Tracker: AAAAAA== X-Xagent-From: guijianfeng@cn.fujitsu.com X-Xagent-To: wuzhy@linux.vnet.ibm.com X-Xagent-Gateway: vmsdvm9.vnet.ibm.com (XAGENTU at VMSDVM9)
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 <agl@us.ibm.com> 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-t...
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. Hi, Gui, QEMU block I/O throttling is not relative to cgroup subsystem, i think. anyway, thanks for your sugguests.
Regards, Zhi Yong Wu
Thanks, Gui
Stefan