diff mbox series

perf/arm-cci: Slightly optimize cci_pmu_sync_counters()

Message ID 88d4e20d595f771396e9d558c1587eb4494057db.1682022422.git.christophe.jaillet@wanadoo.fr
State New
Headers
Series perf/arm-cci: Slightly optimize cci_pmu_sync_counters() |

Commit Message

Christophe JAILLET April 20, 2023, 8:27 p.m. UTC 
  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(-)

Comments

Will Deacon June 5, 2023, 4:35 p.m. UTC | #1 
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 mbox series

Patch

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;
 		}
 	}