| Message ID | 88d4e20d595f771396e9d558c1587eb4494057db.1682022422.git.christophe.jaillet@wanadoo.fr (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | perf/arm-cci: Slightly optimize cci_pmu_sync_counters() | expand |
On Thu, 20 Apr 2023 22:27:24 +0200, Christophe JAILLET wrote: > When the 'mask' bitmap is cleared, it is better to use its full maximum > size instead of only the needed size. > This lets the compiler optimize it because the size is now known at compile > time. HW_CNTRS_MAX is small (i.e. currently 9), so a call to memset() is > saved. > > Also, as 'mask' is local to the function, the non-atomic __set_bit() can > also safely be used here. > > [...] Applied to will (for-next/perf), thanks! [1/1] perf/arm-cci: Slightly optimize cci_pmu_sync_counters() https://git.kernel.org/will/c/f818947a0618 Cheers,
diff --git a/drivers/perf/arm-cci.c b/drivers/perf/arm-cci.c index 03b1309875ae..998259f1d973 100644 --- a/drivers/perf/arm-cci.c +++ b/drivers/perf/arm-cci.c @@ -645,7 +645,7 @@ static void cci_pmu_sync_counters(struct cci_pmu *cci_pmu) struct cci_pmu_hw_events *cci_hw = &cci_pmu->hw_events; DECLARE_BITMAP(mask, HW_CNTRS_MAX); - bitmap_zero(mask, cci_pmu->num_cntrs); + bitmap_zero(mask, HW_CNTRS_MAX); for_each_set_bit(i, cci_pmu->hw_events.used_mask, cci_pmu->num_cntrs) { struct perf_event *event = cci_hw->events[i]; @@ -656,7 +656,7 @@ static void cci_pmu_sync_counters(struct cci_pmu *cci_pmu) if (event->hw.state & PERF_HES_STOPPED) continue; if (event->hw.state & PERF_HES_ARCH) { - set_bit(i, mask); + __set_bit(i, mask); event->hw.state &= ~PERF_HES_ARCH; } }
When the 'mask' bitmap is cleared, it is better to use its full maximum size instead of only the needed size. This lets the compiler optimize it because the size is now known at compile time. HW_CNTRS_MAX is small (i.e. currently 9), so a call to memset() is saved. Also, as 'mask' is local to the function, the non-atomic __set_bit() can also safely be used here. Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> --- drivers/perf/arm-cci.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)