Messages in this thread Patch in this message | | | From | Yury Norov <> | Subject | [PATCH 08/34] drivers/perf: optimize ali_drw_get_counter_idx() by using find_bit() | Date | Sat, 18 Nov 2023 07:50:39 -0800 |
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The function searches used_mask for a set bit in a for-loop bit by bit. We can do it faster by using atomic find_and_set_bit().
Signed-off-by: Yury Norov <yury.norov@gmail.com> --- drivers/perf/alibaba_uncore_drw_pmu.c | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-)
diff --git a/drivers/perf/alibaba_uncore_drw_pmu.c b/drivers/perf/alibaba_uncore_drw_pmu.c index 19d459a36be5..2a3b7701d568 100644 --- a/drivers/perf/alibaba_uncore_drw_pmu.c +++ b/drivers/perf/alibaba_uncore_drw_pmu.c @@ -274,15 +274,9 @@ static const struct attribute_group *ali_drw_pmu_attr_groups[] = { static int ali_drw_get_counter_idx(struct perf_event *event) { struct ali_drw_pmu *drw_pmu = to_ali_drw_pmu(event->pmu); - int idx; + int idx = find_and_set_bit(drw_pmu->used_mask, ALI_DRW_PMU_COMMON_MAX_COUNTERS); - for (idx = 0; idx < ALI_DRW_PMU_COMMON_MAX_COUNTERS; ++idx) { - if (!test_and_set_bit(idx, drw_pmu->used_mask)) - return idx; - } - - /* The counters are all in use. */ - return -EBUSY; + return idx < ALI_DRW_PMU_COMMON_MAX_COUNTERS ? idx : -EBUSY; } static u64 ali_drw_pmu_read_counter(struct perf_event *event) -- 2.39.2
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