Re: [RFC PATCH 0/2] perf_events: add support for per-cpu per-cgroup monitoring (v3)

Peter Zijlstra
2010-09-22T07:28:54Z

On Wed, 2010-09-22 at 09:53 +0530, Balbir Singh wrote:
> Yes, a task can belong to multiple subsystems, hence multiple cgroups.
> Ideally we'd want to use pid + subsystem

Apparently we create a perf subsystem, and we only care about that. So
pid will uniquely identify a cgroup, since for each subsystem a task can
only belong to one cgroup.

> > One thing we could do is pass this cgroup identifier in the pid field
> > and use PERF_FLAG_CGROUP or something. Currently the syscall signature
> > uses pid_t, but I think we can safely change that to int.
>
> Or union it and overload the field to contain either pid_t or fd of the cgroup

Its not a field, its an argument.