[PATCH cgroup/for-3.11 1/3] cgroup: mark "tasks" cgroup file as insane

Vivek Goyal vgoyal at redhat.com
Tue Jun 4 14:34:44 UTC 2013


On Tue, Jun 04, 2013 at 12:15:56PM +0100, Daniel P. Berrange wrote:
> On Mon, Jun 03, 2013 at 07:13:02PM -0700, Tejun Heo wrote:
> > Some resources controlled by cgroup aren't per-task and cgroup core
> > allowing threads of a single thread_group to be in different cgroups
> > forced memcg do explicitly find the group leader and use it.  This is
> > gonna be nasty when transitioning to unified hierarchy and in general
> > we don't want and won't support granularity finer than processes.
> 
> With libvirt and KVM we require the ability to put different threads
> in different cgroups for the "cpu", "cpuset" & "cpuacct" controllers.
> This is to allow us to control schedular tunables / placement for
> QEMU vCPU threads, independantly of limits for QEMU I/O threads. So
> requiring all threads of a process to be in the same cgroup isn't
> sufficiently flexible for our needs.

For placement of vCPU threads, can we set per thread cpu affinity
(sched_setaffinity()), instead of using cgroups for that purpose.

Apart from cpu affinity, what scheduling parameters we want different
between different threads.

Thanks
Vivek


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