From f344011ccb85469445369153c3d27c4ee4bc2ac8 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 22 Jun 2009 13:58:35 +0200 Subject: [PATCH] perf_counter: Optimize perf_counter_alloc()'s inherit case We don't need to add usage counts for swcounter and attr usage models for inherited counters since the parent counter will always have one, which suffices to generate the needed output. This avoids up to 3 global atomic increments per inherited counter. LKML-Reference: Signed-off-by: Peter Zijlstra Signed-off-by: Ingo Molnar --- kernel/perf_counter.c | 32 ++++++++++++++++++++------------ 1 file changed, 20 insertions(+), 12 deletions(-) diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index 0a45490f402..c2b19c11171 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -1508,11 +1508,13 @@ static void free_counter(struct perf_counter *counter) { perf_pending_sync(counter); - atomic_dec(&nr_counters); - if (counter->attr.mmap) - atomic_dec(&nr_mmap_counters); - if (counter->attr.comm) - atomic_dec(&nr_comm_counters); + if (!counter->parent) { + atomic_dec(&nr_counters); + if (counter->attr.mmap) + atomic_dec(&nr_mmap_counters); + if (counter->attr.comm) + atomic_dec(&nr_comm_counters); + } if (counter->destroy) counter->destroy(counter); @@ -3515,6 +3517,8 @@ static void sw_perf_counter_destroy(struct perf_counter *counter) { u64 event = counter->attr.config; + WARN_ON(counter->parent); + atomic_dec(&perf_swcounter_enabled[event]); } @@ -3551,8 +3555,10 @@ static const struct pmu *sw_perf_counter_init(struct perf_counter *counter) case PERF_COUNT_SW_PAGE_FAULTS_MAJ: case PERF_COUNT_SW_CONTEXT_SWITCHES: case PERF_COUNT_SW_CPU_MIGRATIONS: - atomic_inc(&perf_swcounter_enabled[event]); - counter->destroy = sw_perf_counter_destroy; + if (!counter->parent) { + atomic_inc(&perf_swcounter_enabled[event]); + counter->destroy = sw_perf_counter_destroy; + } pmu = &perf_ops_generic; break; } @@ -3663,11 +3669,13 @@ done: counter->pmu = pmu; - atomic_inc(&nr_counters); - if (counter->attr.mmap) - atomic_inc(&nr_mmap_counters); - if (counter->attr.comm) - atomic_inc(&nr_comm_counters); + if (!counter->parent) { + atomic_inc(&nr_counters); + if (counter->attr.mmap) + atomic_inc(&nr_mmap_counters); + if (counter->attr.comm) + atomic_inc(&nr_comm_counters); + } return counter; }