This makes pids.events:max affine to pids.max limit.

How are the new events supposed to be useful?

- pids.events.local:max
  - tells that cgroup's limit is hit (too tight?)
- pids.events:*
  - "only" directs top-down search to cgroups of interest

Changes from v3 (https://lore.kernel.org/r/20240405170548.15234-1-mkoutny@suse.com)
- use existing functions for TAP output in selftest (Muhammad)
- formatting in selftest (Muhammad)
- remove pids.events:max.imposed event, keep it internal (Johannes)
- allow legacy behavior with a mount option
- detach migration charging patches
- drop RFC prefix

Changes from v2 (https://lore.kernel.org/r/20200205134426.10570-1-mkoutny@suse.com)
- implemented pids.events.local (Tejun)
- added migration charging

[1] https://lore.kernel.org/r/20230202155626.1829121-1-hannes@cmpxchg.org/

Michal Koutný (6):
  cgroup/pids: Remove superfluous zeroing
  cgroup/pids: Separate semantics of pids.events related to pids.max
  cgroup/pids: Make event counters hierarchical
  cgroup/pids: Add pids.events.local
  selftests: cgroup: Lexicographic order in Makefile
  selftests: cgroup: Add basic tests for pids controller

 Documentation/admin-guide/cgroup-v1/pids.rst |   3 +-
 Documentation/admin-guide/cgroup-v2.rst      |  12 ++
 include/linux/cgroup-defs.h                  |   7 +-
 kernel/cgroup/cgroup.c                       |  15 +-
 kernel/cgroup/pids.c                         | 131 +++++++++++---
 tools/testing/selftests/cgroup/.gitignore    |  11 +-
 tools/testing/selftests/cgroup/Makefile      |  25 +--
 tools/testing/selftests/cgroup/test_pids.c   | 178 +++++++++++++++++++
 8 files changed, 341 insertions(+), 41 deletions(-)
 create mode 100644 tools/testing/selftests/cgroup/test_pids.c


base-commit: 026e680b0a08a62b1d948e5a8ca78700bfac0e6e
-- 
2.44.0

On Tue, Apr 16, 2024 at 04:20:08PM +0200, Michal Koutný wrote:
> This makes pids.events:max affine to pids.max limit.
> 
> How are the new events supposed to be useful?
> 
> - pids.events.local:max
>   - tells that cgroup's limit is hit (too tight?)
> - pids.events:*
>   - "only" directs top-down search to cgroups of interest

Generally look great to me. If you resend with the couple nits addressed,
I'll apply the rest of the series.

Thanks.

-- 
tejun