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    Subject[PATCH v3 04/10] perf: Add per perf_cpu_context min_heap storage
    From
    Based-on-work-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    Signed-off-by: Ian Rogers <irogers@google.com>
    ---
    include/linux/perf_event.h | 7 ++++++
    kernel/events/core.c | 49 ++++++++++++++++++++++++++++----------
    2 files changed, 44 insertions(+), 12 deletions(-)

    diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
    index 011dcbdbccc2..b3580afbf358 100644
    --- a/include/linux/perf_event.h
    +++ b/include/linux/perf_event.h
    @@ -835,6 +835,13 @@ struct perf_cpu_context {
    int sched_cb_usage;

    int online;
    + /*
    + * Per-CPU storage for iterators used in visit_groups_merge. The default
    + * storage is of size 2 to hold the CPU and any CPU event iterators.
    + */
    + int itr_storage_cap;
    + struct perf_event **itr_storage;
    + struct perf_event *itr_default[2];
    };

    struct perf_output_handle {
    diff --git a/kernel/events/core.c b/kernel/events/core.c
    index a5a3d349a8f1..0dab60bf5935 100644
    --- a/kernel/events/core.c
    +++ b/kernel/events/core.c
    @@ -3403,30 +3403,46 @@ static void __heap_add(struct min_max_heap *heap, struct perf_event *event)
    }
    }

    -static noinline int visit_groups_merge(struct perf_event_groups *groups, int cpu,
    - int (*func)(struct perf_event *, void *), void *data)
    +static noinline int visit_groups_merge(struct perf_cpu_context *cpuctx,
    + struct perf_event_groups *groups, int cpu,
    + int (*func)(struct perf_event *, void *),
    + void *data)
    {
    /* Space for per CPU and/or any CPU event iterators. */
    struct perf_event *itrs[2];
    - struct min_max_heap event_heap = {
    - .data = itrs,
    - .size = 0,
    - .cap = ARRAY_SIZE(itrs),
    - };
    + struct min_max_heap event_heap;
    + struct perf_event **evt;
    struct perf_event *next;
    int ret;

    - __heap_add(&event_heap, perf_event_groups_first(groups, -1));
    + if (cpuctx) {
    + event_heap = (struct min_max_heap){
    + .data = cpuctx->itr_storage,
    + .size = 0,
    + .cap = cpuctx->itr_storage_cap,
    + };
    + } else {
    + event_heap = (struct min_max_heap){
    + .data = itrs,
    + .size = 0,
    + .cap = ARRAY_SIZE(itrs),
    + };
    + /* Events not within a CPU context may be on any CPU. */
    + __heap_add(&event_heap, perf_event_groups_first(groups, -1));
    +
    + }
    + evt = event_heap.data;
    +
    __heap_add(&event_heap, perf_event_groups_first(groups, cpu));

    heapify_all(&event_heap, &perf_min_heap);

    while (event_heap.size) {
    - ret = func(itrs[0], data);
    + ret = func(*evt, data);
    if (ret)
    return ret;

    - next = perf_event_groups_next(itrs[0]);
    + next = perf_event_groups_next(*evt);
    if (next)
    heap_pop_push(&event_heap, &next, &perf_min_heap);
    else
    @@ -3500,7 +3516,10 @@ ctx_pinned_sched_in(struct perf_event_context *ctx,
    .can_add_hw = 1,
    };

    - visit_groups_merge(&ctx->pinned_groups,
    + if (ctx != &cpuctx->ctx)
    + cpuctx = NULL;
    +
    + visit_groups_merge(cpuctx, &ctx->pinned_groups,
    smp_processor_id(),
    pinned_sched_in, &sid);
    }
    @@ -3515,7 +3534,10 @@ ctx_flexible_sched_in(struct perf_event_context *ctx,
    .can_add_hw = 1,
    };

    - visit_groups_merge(&ctx->flexible_groups,
    + if (ctx != &cpuctx->ctx)
    + cpuctx = NULL;
    +
    + visit_groups_merge(cpuctx, &ctx->flexible_groups,
    smp_processor_id(),
    flexible_sched_in, &sid);
    }
    @@ -10182,6 +10204,9 @@ int perf_pmu_register(struct pmu *pmu, const char *name, int type)
    cpuctx->online = cpumask_test_cpu(cpu, perf_online_mask);

    __perf_mux_hrtimer_init(cpuctx, cpu);
    +
    + cpuctx->itr_storage_cap = ARRAY_SIZE(cpuctx->itr_default);
    + cpuctx->itr_storage = cpuctx->itr_default;
    }

    got_cpu_context:
    --
    2.24.0.432.g9d3f5f5b63-goog
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