On Thu, Sep 01, 2011 at 09:49:34AM +0100, Daniel P. Berrange wrote: >From: "Daniel P. Berrange" <berrange@xxxxxxxxxx> >To: Stefan Hajnoczi <stefanha@xxxxxxxxx> >Cc: Zhi Yong Wu <wuzhy@xxxxxxxxxxxxxxxxxx>, libvir-list@xxxxxxxxxx, > agl@xxxxxxxxxx, qemu-devel@xxxxxxxxxx, guijianfeng@xxxxxxxxxxxxxx, > hutao@xxxxxxxxxxxxxx, zwu.kernel@xxxxxxxxx >Subject: Re: [RFC] block I/O throttling: how to enable in libvirt >Message-ID: <20110901084934.GA14462@xxxxxxxxxx> >Reply-To: "Daniel P. Berrange" <berrange@xxxxxxxxxx> >References: <20110901050531.GB17963@xxxxxxxxxxxxxx> > <20110901081149.GB14245@stefanha-thinkpad.localdomain> >MIME-Version: 1.0 >Content-Type: text/plain; charset=utf-8 >Content-Disposition: inline >Content-Transfer-Encoding: 8bit >In-Reply-To: <20110901081149.GB14245@stefanha-thinkpad.localdomain> >User-Agent: Mutt/1.5.21 (2010-09-15) >X-Scanned-By: MIMEDefang 2.67 on 10.5.11.12 >X-Brightmail-Tracker: AAAAAA== >X-Xagent-From: berrange@xxxxxxxxxx >X-Xagent-To: wuzhy@xxxxxxxxxxxxxxxxxx >X-Xagent-Gateway: emeavsc.vnet.ibm.com (XAGENTU at EMEAVSC) > >On Thu, Sep 01, 2011 at 09:11:49AM +0100, 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@xxxxxxxxxx> 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, the virDomainGetBlkioParameters/virDomainSetBlkioParameters >APIs, and blkio virsh command are intended to be a generic interface >for setting any block related tuning parameters, regardless of what >the underling implementation is. So any use of QEMU I/O throttling >features should be added to those APIs/commands. thanks for your suggestions. Regards, Zhi Yong Wu > > >Daniel >-- >|: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| >|: http://libvirt.org -o- http://virt-manager.org :| >|: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| >|: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :| -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list