From 568a2fa10dd06bbd8160e3f8cce9483fabcb7121 Mon Sep 17 00:00:00 2001 From: Yunhui Cui Date: Mon, 4 Aug 2025 10:51:10 +0800 Subject: [PATCH] perf: riscv: skip empty batches in counter start Avoid unnecessary SBI calls when starting non-overflowed counters in pmu_sbi_start_ovf_ctrs_sbi() by checking ctr_start_mask. Signed-off-by: Yunhui Cui Reviewed-by: Anup Patel Link: https://lore.kernel.org/r/20250804025110.11088-1-cuiyunhui@bytedance.com Signed-off-by: Paul Walmsley --- drivers/perf/riscv_pmu_sbi.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c index c18dbffa98345..3fc16bbab0250 100644 --- a/drivers/perf/riscv_pmu_sbi.c +++ b/drivers/perf/riscv_pmu_sbi.c @@ -877,8 +877,10 @@ static inline void pmu_sbi_start_ovf_ctrs_sbi(struct cpu_hw_events *cpu_hw_evt, for (i = 0; i < BITS_TO_LONGS(RISCV_MAX_COUNTERS); i++) { ctr_start_mask = cpu_hw_evt->used_hw_ctrs[i] & ~ctr_ovf_mask; /* Start all the counters that did not overflow in a single shot */ - sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_START, i * BITS_PER_LONG, ctr_start_mask, - 0, 0, 0, 0); + if (ctr_start_mask) { + sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_START, i * BITS_PER_LONG, + ctr_start_mask, 0, 0, 0, 0); + } } /* Reinitialize and start all the counter that overflowed */ -- 2.47.3