Re: [PATCH v2 RESEND] perf/lock: enable end-timestamp accounting for cgroup aggregation

[Arnaldo Carvalho de Melo <acme@kernel.org>]

On Thu, Jun 04, 2026 at 09:31:15AM -0700, Namhyung Kim wrote:
> On Thu, Jun 04, 2026 at 10:37:05AM -0300, Arnaldo Carvalho de Melo wrote:
> > On Sun, May 31, 2026 at 01:29:40AM +0530, Suchit Karunakaran wrote:
> > > update_lock_stat() handles lock contentions that start but never reach a
> > > contention_end event (e.g., locks still held when profiling stops), but
> > > previously treated LOCK_AGGR_CGROUP as a no-op due to missing cgroup
> > > context in userspace.
> > > 
> > > Fix this by adding a cgroup_id field to struct tstamp_data, recording it
> > > at contention_begin using get_current_cgroup_id() when aggr_mode is
> > > LOCK_AGGR_CGROUP. Capturing it at contention_begin is semantically
> > > correct, the contention cost is incurred by the task that had to wait,
> > > not by whatever task happens to be running at contention_end. It is also
> > > preferable from a performance standpoint, as contention_end runs just
> > > before the task enters the critical section.
> > > 
> > > Update contention_end to use pelem->cgroup_id instead of calling
> > > get_current_cgroup_id() dynamically, ensuring both complete and
> > > incomplete contention events attribute the wait time to the cgroup at
> > > wait-start time consistently.
> > 
> > Namhyung, can you provide an Acked-by or Reviewed-by?
> 
> Reviewed-by: Namhyung Kim <namhyung@kernel.org>

Thanks, applied to perf-tools-next, for v7.2.

- Arnaldo