The following commit has been merged into the perf/core branch of tip: Commit-ID: d44f821b0e13275735e8f3fe4db8703b45f05d52 Gitweb: https://git.kernel.org/tip/d44f821b0e13275735e8f3fe4db8703b45f05d52 Author: Liang, Kan <kan.liang@xxxxxxxxxxxxxxx> AuthorDate: Tue, 22 Oct 2019 11:13:09 +02:00 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitterDate: Mon, 28 Oct 2019 12:53:28 +01:00 perf/core: Optimize perf_init_event() for TYPE_SOFTWARE 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). Signed-off-by: Liang, Kan <kan.liang@xxxxxxxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> Cc: Jiri Olsa <jolsa@xxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Mark Rutland <mark.rutland@xxxxxxx> Cc: Namhyung Kim <namhyung@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Stephane Eranian <eranian@xxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Vince Weaver <vincent.weaver@xxxxxxxxx> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- kernel/events/core.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 4d67c5d..cfd89b4 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -10180,7 +10180,16 @@ got_cpu_context: 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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