Messages in this thread | | | Date | Wed, 6 Jun 2018 17:48:39 +0100 | From | Mark Rutland <> | Subject | Re: [PATCH v2 3/5] arm_pmu: Add support for 64bit event counters |
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On Tue, May 29, 2018 at 11:55:54AM +0100, Suzuki K Poulose wrote: > Each PMU has a set of 32bit event counters. But in some > special cases, the events could be counted using counters > which are effectively 64bit wide. > > e.g, Arm V8 PMUv3 has a 64 bit cycle counter which can count > only the CPU cycles. Also, the PMU can chain the event counters > to effectively count as a 64bit counter. > > Add support for tracking the events that uses 64bit counters. > This only affects the periods set for each counter in the core > driver. > > Cc: Mark Rutland <mark.rutland@arm.com> > Cc: Will Deacon <will.deacon@arm.com> > Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> > --- > Changes since v1: > - Rename ARMPMU_EVT_LONG => ARMPMU_EVT_64BIT > --- > drivers/perf/arm_pmu.c | 14 ++++++++------ > include/linux/perf/arm_pmu.h | 6 ++++++ > 2 files changed, 14 insertions(+), 6 deletions(-) > > diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c > index 8962d26..ff858e6 100644 > --- a/drivers/perf/arm_pmu.c > +++ b/drivers/perf/arm_pmu.c > @@ -28,9 +28,10 @@ > static DEFINE_PER_CPU(struct arm_pmu *, cpu_armpmu); > static DEFINE_PER_CPU(int, cpu_irq); > > -static inline u64 arm_pmu_max_period(void) > +static inline u64 arm_pmu_event_max_period(struct perf_event *event) > { > - return (1ULL << 32) - 1; > + return (event->hw.flags & ARMPMU_EVT_64BIT) ? > + ~0ULL : (1ULL << 32) - 1; > }
Could we please have:
static inline u64 arm_pmu_event_max_period(struct perf_event *event) { if (event->hw.flags & ARMPMU_EVT_64BIT) return GENMASK_ULL(63, 0); else return GENMASK_ULL(31, 0); }
... since that's obviously balanced, with both values generated in the same way.
Otherwise this looks good to me.
Thanks, Mark.
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