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ARM: perf: only register a CPU PMU when present

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Currently, an "empty" struct pmu is registered as the CPU PMU,
regardless of whether there is a physical PMU. This burdens the
accessor functions with checks to see whether a PMU is actually
present.

This patch changes initialisation to register a PMU only if there is a
supported PMU present, and removes the checks that this change makes
redundant.

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 2011-04-27 10:31:51 +01:00 committed by Will Deacon
parent 5f12a76193
commit 48957155f8
1 changed files with 2 additions and 16 deletions
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16
arch/arm/kernel/perf_event.c
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@ -250,9 +250,6 @@ armpmu_stop(struct perf_event *event, int flags)
{
struct hw_perf_event *hwc = &event->hw;
if (!armpmu)
return;
/*
* ARM pmu always has to update the counter, so ignore
* PERF_EF_UPDATE, see comments in armpmu_start().
@ -270,9 +267,6 @@ armpmu_start(struct perf_event *event, int flags)
{
struct hw_perf_event *hwc = &event->hw;
if (!armpmu)
return;
/*
* ARM pmu always has to reprogram the period, so ignore
* PERF_EF_RELOAD, see the comment below.
@ -567,9 +561,6 @@ static int armpmu_event_init(struct perf_event *event)
return -ENOENT;
}
if (!armpmu)
return -ENODEV;
event->destroy = hw_perf_event_destroy;
if (!atomic_inc_not_zero(&active_events)) {
@ -599,9 +590,6 @@ static void armpmu_enable(struct pmu *pmu)
int idx, enabled = 0;
struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
if (!armpmu)
return;
for (idx = 0; idx < armpmu->num_events; ++idx) {
struct perf_event *event = cpuc->events[idx];
@ -618,7 +606,6 @@ static void armpmu_enable(struct pmu *pmu)
static void armpmu_disable(struct pmu *pmu)
{
if (armpmu)
armpmu->stop();
}
@ -738,12 +725,11 @@ init_hw_perf_events(void)
if (armpmu) {
pr_info("enabled with %s PMU driver, %d counters available\n",
armpmu->name, armpmu->num_events);
perf_pmu_register(&pmu, "cpu", PERF_TYPE_RAW);
} else {
pr_info("no hardware support available\n");
}
perf_pmu_register(&pmu, "cpu", PERF_TYPE_RAW);
return 0;
}
early_initcall(init_hw_perf_events);