From 5967a19f1c2ffb530f5d4589ddc4b4afbb6c7bd4 Mon Sep 17 00:00:00 2001 From: Ilkka Koskinen Date: Fri, 6 Sep 2024 12:15:39 -0700 Subject: [PATCH] perf: arm_pmuv3: Use BR_RETIRED for HW branch event if enabled The PMU driver attempts to use PC_WRITE_RETIRED for the HW branch event, if enabled. However, PC_WRITE_RETIRED counts only taken branches, whereas BR_RETIRED counts also non-taken ones. Furthermore, perf uses HW branch event to calculate branch misses ratio, implying BR_RETIRED is the correct event to count. We keep PC_WRITE_RETIRED still as an option in case BR_RETIRED isn't implemented. Signed-off-by: Ilkka Koskinen Link: https://lore.kernel.org/r/20240906191539.4847-1-ilkka@os.amperecomputing.com Signed-off-by: Will Deacon --- drivers/perf/arm_pmuv3.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/perf/arm_pmuv3.c b/drivers/perf/arm_pmuv3.c index 4d000532a07f..0afe02f879b4 100644 --- a/drivers/perf/arm_pmuv3.c +++ b/drivers/perf/arm_pmuv3.c @@ -1086,14 +1086,14 @@ static int __armv8_pmuv3_map_event_id(struct arm_pmu *armpmu, if (event->attr.type == PERF_TYPE_HARDWARE && event->attr.config == PERF_COUNT_HW_BRANCH_INSTRUCTIONS) { - if (test_bit(ARMV8_PMUV3_PERFCTR_PC_WRITE_RETIRED, - armpmu->pmceid_bitmap)) - return ARMV8_PMUV3_PERFCTR_PC_WRITE_RETIRED; - if (test_bit(ARMV8_PMUV3_PERFCTR_BR_RETIRED, armpmu->pmceid_bitmap)) return ARMV8_PMUV3_PERFCTR_BR_RETIRED; + if (test_bit(ARMV8_PMUV3_PERFCTR_PC_WRITE_RETIRED, + armpmu->pmceid_bitmap)) + return ARMV8_PMUV3_PERFCTR_PC_WRITE_RETIRED; + return HW_OP_UNSUPPORTED; }