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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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