Jianfeng and Hu Tao, Just want to draw your attention to this thread if you haven't seen it :). Your review and thoughts on I/O throttling in libvirt would be appreciated. Stefan On Mon, Oct 10, 2011 at 2:45 PM, Lei Li <lilei@linux.vnet.ibm.com> wrote:

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 can be applied independently to each drive attached to a guest and supports throughput/iops limits.

To help add QEMU I/O throttling support to libvirt, we plan to complete it with add new API virDomainBlockIoThrottle(), new command 'blkiothrottle' and Python bindings.

Notes: we are sending this series out now(even though they are not completed yet.)because we want to start the review process. These patches implemented the below features by Zhi Yong Wu:

1) Enable the blkio throttling in xml when guest is starting up.

Add blkio throttling in xml as follows:

   <disk type='file' device='disk'>      <driver name='qemu' type='raw'/>      <source file='/var/lib/libvirt/images/kvm-one.img'/>      <target dev='vda' bus='virtio'/>      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>      <iothrottle bps='100000' bps_rd='20000'.../>    </disk>

2) Enable blkio throttling setting at guest running time.

virsh blkiothrottle<domain>   <device>   [--bps<number>] [--bps_rd<number>] \ [--bps_wr<number>] [--iops<number>] [--iops_rd<number>] [--iops_wr<number>]

[PATCH 1/5] Add new API virDomainBlockIoThrottle. [PATCH 2/5] Add virDomainBlockIoThrottle support to the remote driver. [PATCH 3/5] Implement virDomainBlockIoThrottle for the qemu driver. [PATCH 4/5] Enable the virDomainBlockIoThrottle API in virsh. [PATCH 5/5] Enable virDomainBlockIoThrottle in the python API.

And I will address feedback and work on the missing features in few days includes:

3) The support to display the setting for block i/o throttling - HMP/QMP 4) Python binding support. 5) --current --live --config options support to unify the libvirt API.

-- Lei

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