Messages in this thread Patch in this message | | | Date | Tue, 22 Oct 2019 11:20:20 +0200 | From | Peter Zijlstra <> | Subject | [PATCH 3/3] perf: Optimize perf_init_event() for TYPE_SOFTWARE |
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From: "Liang, Kan" <kan.liang@linux.intel.com>
Andi reported that he was hitting the linear search in perf_init_event() a lot. Now that all !TYPE_SOFTWARE events should hit the IDR, make sure the TYPE_SOFTWARE events are at the head of the list such that we'll quickly find the right PMU (provided a valid event was given).
Reported-by: Andi Kleen <andi@firstfloor.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> --- kernel/events/core.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)
--- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -10167,7 +10167,16 @@ int perf_pmu_register(struct pmu *pmu, c if (!pmu->event_idx) pmu->event_idx = perf_event_idx_default; - list_add_rcu(&pmu->entry, &pmus); + /* + * Ensure the TYPE_SOFTWARE PMUs are at the head of the list, + * since these cannot be in the IDR. This way the linear search + * is fast, provided a valid software event is provided. + */ + if (type == PERF_TYPE_SOFTWARE || !name) + list_add_rcu(&pmu->entry, &pmus); + else + list_add_tail_rcu(&pmu->entry, &pmus); + atomic_set(&pmu->exclusive_cnt, 0); ret = 0; unlock:
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