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ARM: perf: lock PMU registers per-CPU

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Currently, a single lock serialises access to CPU PMU registers. This
global locking is unnecessary as PMU registers are local to the CPU
they monitor.

This patch replaces the global lock with a per-CPU lock. As the lock is
in struct cpu_hw_events, PMUs providing a single cpu_hw_events instance
can be locked globally.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Jamie Iles <jamie@jamieiles.com>
Reviewed-by: Ashwin Chaugule <ashwinc@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Mark Rutland
2011-04-28 10:17:04 +01:00
committed by Will Deacon
parent 1b69beb768
commit 0f78d2d5cc
4 changed files with 62 additions and 40 deletions
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17
arch/arm/kernel/perf_event.c
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@@ -26,12 +26,6 @@
#include <asm/pmu.h>
#include <asm/stacktrace.h>
/*
* Hardware lock to serialize accesses to PMU registers. Needed for the
* read/modify/write sequences.
*/
static DEFINE_RAW_SPINLOCK(pmu_lock);
/*
* ARMv6 supports a maximum of 3 events, starting from index 0. If we add
* another platform that supports more, we need to increase this to be the
@@ -55,6 +49,12 @@ struct cpu_hw_events {
* an event. A 0 means that the counter can be used.
*/
unsigned long used_mask[BITS_TO_LONGS(ARMPMU_MAX_HWEVENTS)];
/*
* Hardware lock to serialize accesses to PMU registers. Needed for the
* read/modify/write sequences.
*/
raw_spinlock_t pmu_lock;
};
static DEFINE_PER_CPU(struct cpu_hw_events, cpu_hw_events);
@@ -685,6 +685,11 @@ static struct cpu_hw_events *armpmu_get_cpu_events(void)
static void __init cpu_pmu_init(struct arm_pmu *armpmu)
{
int cpu;
for_each_possible_cpu(cpu) {
struct cpu_hw_events *events = &per_cpu(cpu_hw_events, cpu);
raw_spin_lock_init(&events->pmu_lock);
}
armpmu->get_hw_events = armpmu_get_cpu_events;
}