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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@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Liang, Kan 2019-10-22 11:13:09 +02:00 committed by Ingo Molnar
parent 66d258c5b0
commit d44f821b0e
1 changed files with 10 additions and 1 deletions
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11
kernel/events/core.c
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@ -10180,7 +10180,16 @@ int perf_pmu_register(struct pmu *pmu, const char *name, int type)
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: