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perf: riscv: skip empty batches in counter start

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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 <cuiyunhui@bytedance.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20250804025110.11088-1-cuiyunhui@bytedance.com
Signed-off-by: Paul Walmsley <pjw@kernel.org>
This commit is contained in:
Yunhui Cui 2025-08-04 10:51:10 +08:00 committed by Paul Walmsley
parent f68cd7ddd0
commit 568a2fa10d
1 changed files with 4 additions and 2 deletions
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6
drivers/perf/riscv_pmu_sbi.c
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@ -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 */