The armv8pmu_enable_event_counter function issues an isb instruction after enabling a pair of counters - this doesn't provide any value and is inconsistent with the armv8pmu_disable_event_counter. In any case armv8pmu_enable_event_counter is always called with the PMU stopped. Starting the PMU with armv8pmu_start results in an isb instruction being issued prior to writing to PMCR_EL0. Let's remove the unnecessary isb instruction. Signed-off-by: Andrew Murray <andrew.murray@xxxxxxx> Reviewed-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx> Acked-by: Mark Rutland <mark.rutland@xxxxxxx> --- arch/arm64/kernel/perf_event.c | 1 - 1 file changed, 1 deletion(-) diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c index 8e38d52..de564ae 100644 --- a/arch/arm64/kernel/perf_event.c +++ b/arch/arm64/kernel/perf_event.c @@ -652,7 +652,6 @@ static inline void armv8pmu_enable_event_counter(struct perf_event *event) armv8pmu_enable_counter(idx); if (armv8pmu_event_is_chained(event)) armv8pmu_enable_counter(idx - 1); - isb(); } static inline int armv8pmu_disable_counter(int idx) -- 2.7.4 _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
