[RFC PATCH 02/15] ARM: perf: only register a CPU PMU when present
From: mark.rutland@arm.com (Mark Rutland)
Date: 2011-08-15 13:55:03
Subsystem:
arm pmu profiling and debugging, arm port, performance events subsystem, the rest · Maintainers:
Will Deacon, Mark Rutland, Russell King, Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo, Namhyung Kim, Linus Torvalds
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 <redacted> --- arch/arm/kernel/perf_event.c | 18 ++---------------- 1 files changed, 2 insertions(+), 16 deletions(-)
diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
index 5d60c9c..753648c 100644
--- a/arch/arm/kernel/perf_event.c
+++ b/arch/arm/kernel/perf_event.c@@ -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];
@@ -618,8 +606,7 @@ static void armpmu_enable(struct pmu *pmu) static void armpmu_disable(struct pmu *pmu) { - if (armpmu) - armpmu->stop(); + armpmu->stop(); } static struct pmu pmu = {
@@ -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);
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1.7.0.4