Messages in this thread Patch in this message | | | From | Suzuki K Poulose <> | Subject | [PATCH v2 3/5] arm_pmu: Add support for 64bit event counters | Date | Tue, 29 May 2018 11:55:54 +0100 |
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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; } static int @@ -122,7 +123,7 @@ int armpmu_event_set_period(struct perf_event *event) u64 max_period; int ret = 0; - max_period = arm_pmu_max_period(); + max_period = arm_pmu_event_max_period(event); if (unlikely(left <= -period)) { left = period; local64_set(&hwc->period_left, left); @@ -148,7 +149,7 @@ int armpmu_event_set_period(struct perf_event *event) local64_set(&hwc->prev_count, (u64)-left); - armpmu->write_counter(event, (u64)(-left) & 0xffffffff); + armpmu->write_counter(event, (u64)(-left) & max_period); perf_event_update_userpage(event); @@ -160,7 +161,7 @@ u64 armpmu_event_update(struct perf_event *event) struct arm_pmu *armpmu = to_arm_pmu(event->pmu); struct hw_perf_event *hwc = &event->hw; u64 delta, prev_raw_count, new_raw_count; - u64 max_period = arm_pmu_max_period(); + u64 max_period = arm_pmu_event_max_period(event); again: prev_raw_count = local64_read(&hwc->prev_count); @@ -368,6 +369,7 @@ __hw_perf_event_init(struct perf_event *event) struct hw_perf_event *hwc = &event->hw; int mapping; + hwc->flags = 0; mapping = armpmu->map_event(event); if (mapping < 0) { @@ -410,7 +412,7 @@ __hw_perf_event_init(struct perf_event *event) * is far less likely to overtake the previous one unless * you have some serious IRQ latency issues. */ - hwc->sample_period = arm_pmu_max_period() >> 1; + hwc->sample_period = arm_pmu_event_max_period(event) >> 1; hwc->last_period = hwc->sample_period; local64_set(&hwc->period_left, hwc->sample_period); } diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h index f1cfe12..1e26b14 100644 --- a/include/linux/perf/arm_pmu.h +++ b/include/linux/perf/arm_pmu.h @@ -25,6 +25,12 @@ */ #define ARMPMU_MAX_HWEVENTS 32 +/* + * ARM PMU hw_event flags + */ +/* Event uses a 64bit counter */ +#define ARMPMU_EVT_64BIT 1 + #define HW_OP_UNSUPPORTED 0xFFFF #define C(_x) PERF_COUNT_HW_CACHE_##_x #define CACHE_OP_UNSUPPORTED 0xFFFF -- 2.7.4
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