On 10/29/2012 02:32 AM, erkan yanar wrote: Yes, via <blkiotune> in the XML, or 'virsh blkiotune': http://libvirt.org/formatdomain.html#elementsBlockTuning But note that <blkiotune> is not necessarily the best way to tune I/O; if you have new enough qemu, you might find better results with per-device tuning by using <iotune>, or 'virsh 'blkdeviotune': http://libvirt.org/formatdomain.html#elementsDisks -- Eric Blake eblake(a)redhat.com +1-919-301-3266 Libvirt virtualization library http://libvirt.org

On 10/29/2012 03:22 PM, erkan yanar wrote: In the case of qemu - if you stick two disk images as files residing within the same file system on the same block device from the host perspective, then <blkiotune> can only throttle the underlying device (the two disks share the same throttling, and you have no control over one disk can starve the other within the guest - due to cgroup doing the throttling via the host), whereas per-device <iotune> can individually throttle the two disk images at different rates (completely independent throttling, due to qemu doing the throttling at the disk image layer). Indeed - with LXC, all you can use is <blkiotune> to throttle individual block devices passed through to the guest, as LXC isn't really using disk images in the same manner as qemu, and therefore isn't implementing per-disk-image throttling of <iotune>. So overall, I'm not saying that <blkiotune> is bad, just that it can't do everything that qemu can do. But what qemu can do may be irrelevant to your LXC usage, so give <blkiotune> a try :) -- Eric Blake eblake(a)redhat.com +1-919-301-3266 Libvirt virtualization library http://libvirt.org