On 10/29/2012 03:22 PM, erkan yanar wrote: > Hi Eric, > > On Mon, Oct 29, 2012 at 02:28:25PM -0600, Eric Blake wrote: >> On 10/29/2012 02:32 AM, erkan yanar wrote: >>> >>> Hi, >>> >>> is there a way to configure blkio via libvirt (xml)? >> >> Yes, via <blkiotune> in the XML, or 'virsh blkiotune': >> http://libvirt.org/formatdomain.html#elementsBlockTuning > > facepalm .. thx >> >> 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 > > Uh whats so bad about blkiotune? 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). > As Im stucked to LXC Ive got no great choice. 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@xxxxxxxxxx +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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