# Re: \[PATCH v3 00/14\] perf/hw\_breakpoint: Optimize for thousands of tasks

- From: Marco Elver \<elver@google.com\>
- Date: 2022-07-12 13:41:37 
- List: linuxppc-dev
- Page: https://ratatoskr.run/linuxppc-dev/2022/07/1856083
- Thread: https://ratatoskr.run/linuxppc-dev/2022/07/1845740/t.md

```text
On Mon, 4 Jul 2022 at 17:05, Marco Elver [ref] wrote:
>
> The hw_breakpoint subsystem's code has seen little change in over 10
> years. In that time, systems with >100s of CPUs have become common,
> along with improvements to the perf subsystem: using breakpoints on
> thousands of concurrent tasks should be a supported usecase.
[...]
> Marco Elver (14):
>   perf/hw_breakpoint: Add KUnit test for constraints accounting
>   perf/hw_breakpoint: Provide hw_breakpoint_is_used() and use in test
>   perf/hw_breakpoint: Clean up headers
>   perf/hw_breakpoint: Optimize list of per-task breakpoints
>   perf/hw_breakpoint: Mark data __ro_after_init
>   perf/hw_breakpoint: Optimize constant number of breakpoint slots
>   perf/hw_breakpoint: Make hw_breakpoint_weight() inlinable
>   perf/hw_breakpoint: Remove useless code related to flexible
>     breakpoints
>   powerpc/hw_breakpoint: Avoid relying on caller synchronization
>   locking/percpu-rwsem: Add percpu_is_write_locked() and
>     percpu_is_read_locked()
>   perf/hw_breakpoint: Reduce contention with large number of tasks
>   perf/hw_breakpoint: Introduce bp_slots_histogram
>   perf/hw_breakpoint: Optimize max_bp_pinned_slots() for CPU-independent
>     task targets
>   perf/hw_breakpoint: Optimize toggle_bp_slot() for CPU-independent task
>     targets
[...]

This is ready from our side, and given the silence, assume it's ready
to pick up and/or have a maintainer take a look. Since this is mostly
kernel/events, would -tip/perf/core be appropriate?

Thanks,
-- Marco
```