On Wed, 20 Jul 2022 at 17:47, Ian Rogers [off-list ref] wrote:

On Tue, Jul 12, 2022 at 6:41 AM Marco Elver [off-list ref] wrote:

quoted

On Mon, 4 Jul 2022 at 17:05, Marco Elver [off-list ref] wrote:

quoted

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.

[...]

quoted

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?

These are awesome improvements, I've added my acked-by to every
change. I hope we can pull these changes, as you say, into tip.git
perf/core and get them into 5.20.

These still apply cleanly to 6.0-rc1 and the test passes, but let me
know if I shall send a rebased version.

Thanks
-- Marco