Commit 8d3e9942 authored by Suzuki K Poulose's avatar Suzuki K Poulose Committed by Will Deacon
Browse files

arm_pmu: Clean up maximum period handling 



Each PMU defines their max_period of the counter as the maximum
value that can be counted. Since all the PMU backends support
32bit counters by default, let us remove the redundant field.

No functional changes.

Cc: Will Deacon <will.deacon@arm.com>
Acked-by: default avatarMark Rutland <mark.rutland@arm.com>
Reviewed-by: default avatarJulien Thierry <julien.thierry@arm.com>
Signed-off-by: default avatarSuzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent 64b2f025

arch/arm/kernel/perf_event_v6.c

+0 −2
Original line number Diff line number Diff line
@@ -495,7 +495,6 @@ static void armv6pmu_init(struct arm_pmu *cpu_pmu) 
	cpu_pmu->stop		= armv6pmu_stop;

	cpu_pmu->map_event	= armv6_map_event;

	cpu_pmu->num_events	= 3;

	cpu_pmu->max_period	= (1LLU << 32) - 1;

}



static int armv6_1136_pmu_init(struct arm_pmu *cpu_pmu)
@@ -546,7 +545,6 @@ static int armv6mpcore_pmu_init(struct arm_pmu *cpu_pmu) 
	cpu_pmu->stop		= armv6pmu_stop;

	cpu_pmu->map_event	= armv6mpcore_map_event;

	cpu_pmu->num_events	= 3;

	cpu_pmu->max_period	= (1LLU << 32) - 1;



	return 0;

}

arch/arm/kernel/perf_event_v7.c

+0 −1
Original line number Diff line number Diff line
@@ -1170,7 +1170,6 @@ static void armv7pmu_init(struct arm_pmu *cpu_pmu) 
	cpu_pmu->start		= armv7pmu_start;

	cpu_pmu->stop		= armv7pmu_stop;

	cpu_pmu->reset		= armv7pmu_reset;

	cpu_pmu->max_period	= (1LLU << 32) - 1;

};



static void armv7_read_num_pmnc_events(void *info)

arch/arm/kernel/perf_event_xscale.c

+0 −2
Original line number Diff line number Diff line
@@ -374,7 +374,6 @@ static int xscale1pmu_init(struct arm_pmu *cpu_pmu) 
	cpu_pmu->stop		= xscale1pmu_stop;

	cpu_pmu->map_event	= xscale_map_event;

	cpu_pmu->num_events	= 3;

	cpu_pmu->max_period	= (1LLU << 32) - 1;



	return 0;

}
@@ -743,7 +742,6 @@ static int xscale2pmu_init(struct arm_pmu *cpu_pmu) 
	cpu_pmu->stop		= xscale2pmu_stop;

	cpu_pmu->map_event	= xscale_map_event;

	cpu_pmu->num_events	= 5;

	cpu_pmu->max_period	= (1LLU << 32) - 1;



	return 0;

}

arch/arm64/kernel/perf_event.c

+0 −1
Original line number Diff line number Diff line
@@ -960,7 +960,6 @@ static int armv8_pmu_init(struct arm_pmu *cpu_pmu) 
	cpu_pmu->start			= armv8pmu_start,

	cpu_pmu->stop			= armv8pmu_stop,

	cpu_pmu->reset			= armv8pmu_reset,

	cpu_pmu->max_period		= (1LLU << 32) - 1,

	cpu_pmu->set_event_filter	= armv8pmu_set_event_filter;



	return 0;

drivers/perf/arm_pmu.c

+12 −4
Original line number Diff line number Diff line
@@ -28,6 +28,11 @@ 
static DEFINE_PER_CPU(struct arm_pmu *, cpu_armpmu);

static DEFINE_PER_CPU(int, cpu_irq);



static inline u64 arm_pmu_max_period(void)

{

	return (1ULL << 32) - 1;

}



static int

armpmu_map_cache_event(const unsigned (*cache_map)

				      [PERF_COUNT_HW_CACHE_MAX]
@@ -114,8 +119,10 @@ int armpmu_event_set_period(struct perf_event *event) 
	struct hw_perf_event *hwc = &event->hw;

	s64 left = local64_read(&hwc->period_left);

	s64 period = hwc->sample_period;

	u64 max_period;

	int ret = 0;



	max_period = arm_pmu_max_period();

	if (unlikely(left <= -period)) {

		left = period;

		local64_set(&hwc->period_left, left);
@@ -136,8 +143,8 @@ int armpmu_event_set_period(struct perf_event *event) 
	 * effect we are reducing max_period to account for

	 * interrupt latency (and we are being very conservative).

	 */

	if (left > (armpmu->max_period >> 1))

		left = armpmu->max_period >> 1;

	if (left > (max_period >> 1))

		left = (max_period >> 1);



	local64_set(&hwc->prev_count, (u64)-left);
@@ -153,6 +160,7 @@ 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();



again:

	prev_raw_count = local64_read(&hwc->prev_count);
@@ -162,7 +170,7 @@ again: 
			     new_raw_count) != prev_raw_count)

		goto again;



	delta = (new_raw_count - prev_raw_count) & armpmu->max_period;

	delta = (new_raw_count - prev_raw_count) & max_period;



	local64_add(delta, &event->count);

	local64_sub(delta, &hwc->period_left);
@@ -402,7 +410,7 @@ __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  = armpmu->max_period >> 1;

		hwc->sample_period  = arm_pmu_max_period() >> 1;

		hwc->last_period    = hwc->sample_period;

		local64_set(&hwc->period_left, hwc->sample_period);

	}

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