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    SubjectRe: [PATCH v7] perf: Sharing PMU counters across compatible events
    On Fri, Nov 15, 2019 at 03:55:04PM -0800, Song Liu wrote:
    > This patch tries to enable PMU sharing. When multiple perf_events are
    > counting the same metric, they can share the hardware PMU counter. We
    > call these events as "compatible events".
    >
    > The PMU sharing are limited to events within the same perf_event_context
    > (ctx). When a event is installed or enabled, search the ctx for compatible
    > events. This is implemented in perf_event_setup_dup(). One of these
    > compatible events are picked as the master (stored in event->dup_master).
    > Similarly, when the event is removed or disabled, perf_event_remove_dup()
    > is used to clean up sharing.
    >
    > A new state PERF_EVENT_STATE_ENABLED is introduced for the master event.
    > This state is used when the slave event is ACTIVE, but the master event
    > is not.
    >
    > On the critical paths (add, del read), sharing PMU counters doesn't
    > increase the complexity. Helper functions event_pmu_[add|del|read]() are
    > introduced to cover these cases. All these functions have O(1) time
    > complexity.
    >
    > Cc: Peter Zijlstra <peterz@infradead.org>
    > Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
    > Cc: Jiri Olsa <jolsa@kernel.org>
    > Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
    > Cc: Namhyung Kim <namhyung@kernel.org>
    > Cc: Tejun Heo <tj@kernel.org>
    > Signed-off-by: Song Liu <songliubraving@fb.com>
    >
    > ---
    > Changes in v7:
    > Major rewrite to avoid allocating extra master event.

    hi,
    what is this based on? I can't apply it on tip/master:

    Applying: perf: Sharing PMU counters across compatible events
    error: patch failed: include/linux/perf_event.h:722
    error: include/linux/perf_event.h: patch does not apply
    Patch failed at 0001 perf: Sharing PMU counters across compatible events
    hint: Use 'git am --show-current-patch' to see the failed patch
    When you have resolved this problem, run "git am --continue".
    If you prefer to skip this patch, run "git am --skip" instead.
    To restore the original branch and stop patching, run "git am --abort".

    also I'm getting this when trying to see/apply plain text patch:

    [jolsa@dell-r440-01 linux-perf]$ git am --show-current-patch | tail
    =09=09for_each_sibling_event(sibling, group_leader) {
    =09=09=09perf_remove_from_context(sibling, 0);
    =09=09=09put_ctx(gctx);
    +=09=09=09WARN_ON_ONCE(sibling->dup_master);
    =09=09}
    =20
    =09=09/*
    --=20
    2.17.1


    jirka

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