Re: [patch] sched: fix uneven per-cpu task_group share distribution

[Peter Zijlstra]

On Wed, 2008-12-17 at 00:20 -0800, Ken Chen wrote:
> On Mon, Dec 15, 2008 at 11:37 PM, Ken Chen <kenchen@xxxxxxxxxx> wrote:
> > While testing CFS scheduler on linux-2.6-tip tree
> > git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
> >
> > We found that task which is pinned to a CPU could be starved relative to its
> > allocated fair share.
> 
> I just want to poke you two to see if you have time to look over this
> patch.  There is a real bug in linux-2.6-tip tree.
> 
> If I create a CFS cgroup under directory .../parent/cgdir, put one
> task under 'parent' with CFS weight 1024, and one task under 'cgdir'
> (cgdir has group weight of 1024 also), pin both tasks onto same CPU.
> The CPU cycle allocation on these two tasks will be N:1 where N is
> number of CPUs in the system.  The expected allocation should be 1:1.

right - it was on the todo list, let me stare at it a little..

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