Re: [PATCH 2/2] cgroup, perf_event: make perf_event controller work on cgroup2 hierarchy

[Peter Zijlstra]

On Wed, Feb 24, 2016 at 05:12:55PM -0500, Tejun Heo wrote:
> perf_event is a utility controller whose primary role is identifying
> cgroup membership to filter perf events; however, because it also
> tracks some per-css state, it can't be replaced by pure cgroup
> membership test.  Mark the controller as implicitly enabled on the
> default hierarchy so that perf events can always be filtered based on
> cgroup v2 path as long as the controller is not mounted on a legacy
> hierarchy.
> 
> "perf record" is updated accordingly so that it searches for both v1
> and v2 hierarchies.  A v1 hierarchy is used if perf_event is mounted
> on it; otherwise, it uses the v2 hierarchy.
> 
> v2: Doc updated to reflect more flexible rebinding behavior.
> 
> Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
> Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>

Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>

> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>

Arnaldo, do the userspace bits look ok?