On Thu, Sep 01, 2011 at 01:05:31PM +0800, Zhi Yong Wu wrote: >----- Forwarded message from Zhi Yong Wu <wu...@linux.vnet.ibm.com> ----- >Date: Thu, 1 Sep 2011 11:55:17 +0800 >From: Zhi Yong Wu <wu...@linux.vnet.ibm.com> >To: Stefan Hajnoczi <stefa...@gmail.com> >Cc: "Daniel P. Berrange" <berra...@redhat.com>, Stefan Hajnoczi > <stefa...@gmail.com>, Adam Litke <a...@us.ibm.com>, Zhi Yong Wu > <wu...@linux.vnet.ibm.com>, QEMU Developers <qemu-de...@nongnu.org>, > guijianf...@cn.fujitsu.com, hu...@cn.fujitsu.com >Subject: [RFC] block I/O throttling: how to enable in libvirt >Message-ID: <20110901035517.gd16...@f15.cn.ibm.com> >References: ><CAEH94Li_C=BOe2gV8NyM48njYWMBAo9MTGc1eUOh-Y=cods...@mail.gmail.com> > <CAJSP0QW1CPCokX=F5z7y==vn1s4wh0vtoaq7oj4kc7f7uqm...@mail.gmail.com> > <20110830134636.gb29...@aglitke.rchland.ibm.com> > <CAJSP0QUHm=y8xjc_kxrg7uffzt3k_xddfqb--sxjc+c0gjo...@mail.gmail.com> >MIME-Version: 1.0 >Content-Type: text/plain; charset=utf-8 >Content-Disposition: inline >Content-Transfer-Encoding: 8bit >In-Reply-To: ><CAJSP0QUHm=y8xjc_kxrg7uffzt3k_xddfqb--sxjc+c0gjo...@mail.gmail.com> >User-Agent: Mutt/1.5.21 (2010-09-15) >X-Xagent-From: wu...@linux.vnet.ibm.com >X-Xagent-To: wu...@linux.vnet.ibm.com >X-Xagent-Gateway: vmsdvma.vnet.ibm.com (XAGENTU7 at VMSDVMA) > >On Wed, Aug 31, 2011 at 08:18:19AM +0100, Stefan Hajnoczi wrote: >>Subject: Re: The design choice for how to enable block I/O throttling >> function in libvirt >>From: Stefan Hajnoczi <stefa...@gmail.com> >>To: Adam Litke <a...@us.ibm.com> >>Cc: libvir-list@redhat.com, "Daniel P. Berrange" <berra...@redhat.com>, Zhi >> Yong Wu <wu...@linux.vnet.ibm.com>, Zhi Yong Wu <zwu.ker...@gmail.com> >>Content-Type: text/plain; charset=ISO-8859-1 >>Content-Transfer-Encoding: quoted-printable >>X-Brightmail-Tracker: AAAAAA== >>X-Xagent-From: stefa...@gmail.com >>X-Xagent-To: wu...@linux.vnet.ibm.com >>X-Xagent-Gateway: bldgate.vnet.ibm.com (XAGENTU7 at BLDGATE) >> >>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: >>>> On Tue, Aug 30, 2011 at 3:55 AM, Zhi Yong Wu <zwu.ker...@gmail.com> wrote: >>>> > I am trying to enable block I/O throttling function in libvirt. But >>>> > currently i met some design questions, and don't make sure if we >>>> > should extend blkiotune to support block I/O throttling or introduce >>>> > one new libvirt command "blkiothrottle" to cover it or not. If you >>>> > have some better idea, pls don't hesitate to drop your comments. >>>> >>>> A little bit of context: this discussion is about adding libvirt >>>> support for QEMU disk I/O throttling. >>> >>> Thanks for the additional context Stefan. >>> >>>> Today libvirt supports the cgroups blkio-controller, which handles >>>> proportional shares and throughput/iops limits on host block devices. >>>> blkio-controller does not support network file systems (NFS) or other >>>> QEMU remote block drivers (curl, Ceph/rbd, sheepdog) since they are >>>> not host block devices. QEMU I/O throttling works with all types of >>>> -drive and therefore complements blkio-controller. >>> >>> The first question that pops into my mind is: Should a user need to >>> understand >>> when to use the cgroups blkio-controller vs. the QEMU I/O throttling >>> method? In >>> my opinion, it would be nice if libvirt had a single interface for block I/O >>> throttling and libvirt would decide which mechanism to use based on the >>> type of >>> device and the specific limits that need to be set. >> >>Yes, I agree it would be simplest to pick the right mechanism, >>depending on the type of throttling the user wants. More below. >> >>>> 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. > >Daniel and other maintainers, > >If you are available, can you make some comments for us?:) HI, Adam, Now stefan, Daniel, and Gui all suggest extending blkiotune to keep libivrt unified interface. What do you think of it?
Regards, Zhi Yong Wu > > >Regards, > >Zhi Yong Wu >> >>Stefan > >----- End forwarded message ----- > >-- >libvir-list mailing list >libvir-list@redhat.com >https://www.redhat.com/mailman/listinfo/libvir-list -- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
