Commit 568a2fa1 authored by Yunhui Cui's avatar Yunhui Cui Committed by Paul Walmsley
Browse files

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: default avatarYunhui Cui <cuiyunhui@bytedance.com>
Reviewed-by: default avatarAnup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20250804025110.11088-1-cuiyunhui@bytedance.com


Signed-off-by: default avatarPaul Walmsley <pjw@kernel.org>
parent f68cd7dd

drivers/perf/riscv_pmu_sbi.c

+4 −2
Original line number Diff line number Diff line
@@ -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 */