On Thu, Sep 01, 2011 at 09:11:49AM +0100, Stefan Hajnoczi wrote: >Date: Thu, 1 Sep 2011 09:11:49 +0100 >From: Stefan Hajnoczi <stefa...@gmail.com> >To: Zhi Yong Wu <wu...@linux.vnet.ibm.com> >Message-ID: <20110901081149.GB14245@stefanha-thinkpad.localdomain> >References: <20110901050531.gb17...@f15.cn.ibm.com> >MIME-Version: 1.0 >Content-Type: text/plain; charset=iso-8859-1 >Content-Disposition: inline >Content-Transfer-Encoding: 8bit >In-Reply-To: <20110901050531.gb17...@f15.cn.ibm.com> >User-Agent: Mutt/1.5.21 (2010-09-15) >X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6 (newer, 2) >X-Received-From: 74.125.82.173 >Cc: libvir-list@redhat.com, guijianf...@cn.fujitsu.com, a...@us.ibm.com, > qemu-de...@nongnu.org, zwu.ker...@gmail.com, hu...@cn.fujitsu.com >Subject: Re: [Qemu-devel] [RFC] block I/O throttling: how to enable in > libvirt >X-BeenThere: qemu-de...@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-requ...@nongnu.org?subject=unsubscribe> >List-Archive: </archive/html/qemu-devel> >List-Post: <mailto:qemu-de...@nongnu.org> >List-Help: <mailto:qemu-devel-requ...@nongnu.org?subject=help> >List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>, > <mailto:qemu-devel-requ...@nongnu.org?subject=subscribe> >X-Mailman-Copy: yes >Errors-To: qemu-devel-bounces+wuzhy=linux.vnet.ibm....@nongnu.org >Sender: qemu-devel-bounces+wuzhy=linux.vnet.ibm....@nongnu.org >x-cbid: 11090108-7282-0000-0000-0000010970B0 >X-IBM-ISS-SpamDetectors: Score=0; BY=0; FL=0; FP=0; FZ=0; HX=0; KW=0; PH=0; > SC=0; ST=0; TS=0; UL=0; ISC= >X-IBM-ISS-DetailInfo: BY=3.00000211; HX=3.00000168; KW=3.00000007; > PH=3.00000001; SC=3.00000001; SDB=6.00067104; UDB=6.00020326; > UTC=2011-09-01 08:12:15 >X-Xagent-From: stefa...@gmail.com >X-Xagent-To: wu...@linux.vnet.ibm.com >X-Xagent-Gateway: vmsdvm6.vnet.ibm.com (XAGENTU5 at VMSDVM6) > >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 <a...@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-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. QEMU I/O throttling currently don't support those options of blkiotune, such as --live, --config and --current.If those bps/iops settings are modified, it will immediately take effect.
Regards, Zhi Yong Wu > >Stefan > -- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
