| Message ID | 20231118155105.25678-9-yury.norov@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | None | expand |
On Sat, Nov 18, 2023 at 07:50:39AM -0800, Yury Norov wrote: > 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 Acked-by: Will Deacon <will@kernel.org> Will
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)
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(-)