Re: [libvirt] About cgroup mechanism using in libvirt

On Mon, Jun 14, 2010 at 3:10 PM, Daniel P. Berrange <berrange(a)redhat.com&gt; wrote: > On Sat, Jun 12, 2010 at 07:23:33AM -0400, Alex Jia wrote: >> Hey Daniel, >> The cgroup mechanism have been integrated into libvirt for LXC and QEMU driver, >> and the LXC driver uses all of cgroup controllers except for net_cls and cpuset, >> while the QEMU driver only uses the cpu and devices controllers at present. >> >> From the user point of view, user can use some virsh commands to control some >> guest resources: >> 1. Using 'virsh schedinfo' command to get/set CPU scheduler priority for a guest > > QEMU + LXC use the cpu controller 'cpu_shares' tunable > >> 2. Using 'virsh vcpuin' command to control guest vcpu affinity > > QEMU pins the process directly, doesn't use cgroups.  LXC has't > implemented this yet > >> 3. Using 'virsh setmem' command to change memory allocation >> 4. Using 'virsh setmaxmem' command to change maximum memory limit > > QEMU uses balloon driver.  LXC uses cgroups memory controller > Not sure if I understand this, but the balloon driver and memory cgroups are not mutually exclusive. One could use both together and I would certainly like to see additional commands to support cgroups. What happens if a guest (like freebsd) does not support ballooning? Are you suggesting we'll not need cgroups at all with QEMU?

>> 5. Using 'virsh setvcpus' command to change number of virtual CPUs > > QEMU uses cpu hotplug. LXC hasn't implemented this. > >> I just make sure the above 1 using CPU scheduler controller, maybe 4 using Memory >> controller? and maybe 5 using CPU set controller? I am not sure. >> I think we'll some notion of soft limits as well, not sure if they can be encapsulated using the current set. We need memory shares for example to encapsulate them.