Re: [libvirt] The design choice for how to enable block I/O throttling function in libvirt
On Tue, Aug 30, 2011 at 3:55 AM, Zhi Yong Wu <zwu.kernel(a)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.
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.
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-i...
Stefan