Commit d44f821b authored Oct 22, 2019 by Liang, Kan Committed by Ingo Molnar Oct 28, 2019

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>

parent 66d258c5

kernel/events/core.c

+10 −1

Original line number	Diff line number	Diff line
		@@ -10180,7 +10180,16 @@ got_cpu_context:
		if (!pmu->event_idx)
		pmu->event_idx = perf_event_idx_default;

		/*
		* 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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