Re: [PATCH v2] sched/core: Don't mix isolcpus and housekeeping CPUs

From: Peter Zijlstra
Date: Fri Oct 26 2018 - 04:50:02 EST

On Thu, Oct 25, 2018 at 11:53:17PM +0530, Srikar Dronamraju wrote:
> >
> > You can create multiple partitions with cpusets but still have an
> > unbound task in the root cgroup. That would suffer the exact same
> > problems.
> >
> I probably don't understand this. Even if the child cgroups has
> cpu_exclusive or sched_load_balance reset, the tasks in root cgroup has
> access to all cpus in system. Right?

The crucial word being 'access'. The root group will not impose a limit
on the affinity of tasks. So you can indeed have affinities that span
load balancing domains.

And yes, that leads to 'interesting' but specified behaviour.