Re: [libvirt] [PATCHv4 4/4] blkiotune: add qemu support for blkiotune.device_weight

On 11/29/2011 10:14 AM, Daniel P. Berrange wrote: Okay, the series is now pushed with this last round of improvements included. However, I'm still working on a 5/4. Consider: # virsh blkiotune dom --device-weights /dev/sda,502,/dev/sdb,498 # virsh blkiotune dom --device-weights /dev/sda,503 # virsh blkiotune dom weight : 500 device_weight : /dev/sda,503 # cat /cgroup/blkio/libvirt/qemu/dom/blkio.weight_device 8:0 503 8:16 498 Oops - /dev/sdb wasn't cleared, even though our new query no longer reports it. Calling virsh blkiotune dome --device-weights should either clear all existing weights before writing in just the specified weights of the new string. Or it should only affect the weights of paths specified in the new string, while preserving all pre-existing weights for all other paths. I'm leaning towards the latter (that is, you _have_ to pass an explicit 0 to set in order to remove /dev/sdb from the XML and from get, and that mentioning just /dev/sda on set leaves /dev/sdb's setting alone). Besides, that's how cgroups does it - write an explicit 0 to remove a device from the cgroup file; all other writes modify a device if it is already listed, otherwise they add a new line to the file. -- Eric Blake eblake(a)redhat.com +1-919-301-3266 Libvirt virtualization library http://libvirt.org