Re: [PATCH v2 2/6] perf/core: Introduce percpu perf_cgroup

[Namhyung Kim]

On Tue, Mar 22, 2022 at 6:01 AM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>
> On Tue, Mar 22, 2022 at 08:08:30PM +0800, Chengming Zhou wrote:
> > Although we don't have incosistency problem any more, we can
> > have other problem like:
> >
> > CPU1                                  CPU2
> > (in context_switch)                   (attach running task)
> >                                       prev->cgroups = cgrp2
> > perf_cgroup_sched_switch(prev, next)
> >       cgrp2 == cgrp2 is True
> >
>
> Again, I'm not following, how can you attach to a running task from
> another CPU ?

I think it's supported from the beginning by writing PID to a file
in the cgroupfs.

Thanks,
Namhyung