On Tue, Nov 20, 2018 at 02:15:19PM +0000, Andrew Murray wrote: > 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. > > Let's remove the unnecessary isb instruction. > > Signed-off-by: Andrew Murray <andrew.murray@xxxxxxx> Acked-by: Mark Rutland <mark.rutland@xxxxxxx> ... though it would be nice to explicitly point out that the ISB in armv8pmu_start() is before the write to PMCR_EL1, if you happen to respin this patch. Mark. > --- > 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
