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From:   Marco Elver <elver@google.com>
Date:   Tue, 12 Jul 2022 15:39:57 +0200
Message-ID: <CANpmjNP0hPuhXmZmkX1ytCDh56LOAmxJjf7RyfxOvoaem=2d8Q@mail.gmail.com>
Subject: Re: [PATCH v3 00/14] perf/hw_breakpoint: Optimize for thousands of tasks
To:     elver@google.com, Peter Zijlstra <peterz@infradead.org>,
        Frederic Weisbecker <frederic@kernel.org>,
        Ingo Molnar <mingo@kernel.org>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@redhat.com>,
        Namhyung Kim <namhyung@kernel.org>,
        Dmitry Vyukov <dvyukov@google.com>,
        Michael Ellerman <mpe@ellerman.id.au>,
        linuxppc-dev@lists.ozlabs.org, linux-perf-users@vger.kernel.org,
        x86@kernel.org, linux-sh@vger.kernel.org,
        kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org
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On Mon, 4 Jul 2022 at 17:05, Marco Elver <elver@google.com> 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