Messages in this thread Patch in this message | | | From | Stephane Eranian <> | Subject | [PATCH v3 2/2] perf: add sysfs entry to adjust multiplexing interval per PMU | Date | Thu, 13 Sep 2012 16:10:57 +0200 |
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This patch adds /sys/device/xxx/mux_interval_ms to ajust the multiplexing interval per PMU. The unit is milliseconds. Value has to be >= 1.
Signed-off-by: Stephane Eranian <eranian@google.com> --- include/linux/perf_event.h | 1 + kernel/events/core.c | 54 ++++++++++++++++++++++++++++++++++++++++--- 2 files changed, 51 insertions(+), 4 deletions(-)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 204e1dc..ef1a6fe 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -784,6 +784,7 @@ struct pmu { int * __percpu pmu_disable_count; struct perf_cpu_context * __percpu pmu_cpu_context; int task_ctx_nr; + int hrtimer_interval_ms; /* * Fully disable/enable this PMU, can be used to protect from the PMI diff --git a/kernel/events/core.c b/kernel/events/core.c index cb9d811..de0ef2b 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -690,13 +690,21 @@ static void __perf_cpu_hrtimer_init(struct perf_cpu_context *cpuctx, int cpu) { struct hrtimer *hr = &cpuctx->hrtimer; struct pmu *pmu = cpuctx->ctx.pmu; + int timer; /* no multiplexing needed for SW PMU */ if (pmu->task_ctx_nr == perf_sw_context) return; - cpuctx->hrtimer_interval = - ns_to_ktime(NSEC_PER_MSEC * PERF_CPU_HRTIMER); + /* + * check default is sane, if not set then force to + * default interval (1/tick) + */ + timer = pmu->hrtimer_interval_ms; + if (timer < 1) + timer = pmu->hrtimer_interval_ms = PERF_CPU_HRTIMER; + + cpuctx->hrtimer_interval = ns_to_ktime(NSEC_PER_MSEC * timer); hrtimer_init(hr, CLOCK_MONOTONIC, HRTIMER_MODE_REL_PINNED); hr->function = perf_cpu_hrtimer_handler; @@ -5993,9 +6001,47 @@ type_show(struct device *dev, struct device_attribute *attr, char *page) return snprintf(page, PAGE_SIZE-1, "%d\n", pmu->type); } +static ssize_t +mux_interval_ms_show(struct device *dev, struct device_attribute *attr, + char *page) +{ + struct pmu *pmu = dev_get_drvdata(dev); + + return snprintf(page, PAGE_SIZE-1, "%d\n", pmu->hrtimer_interval_ms); +} + +static ssize_t +mux_interval_ms_store(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count) +{ + struct pmu *pmu = dev_get_drvdata(dev); + int timer, cpu, ret; + + ret = kstrtoint(buf, 0, &timer); + if (ret) + return ret; + + if (timer < 1) + return -EINVAL; + + pmu->hrtimer_interval_ms = timer; + + /* update all cpuctx for this PMU */ + for_each_possible_cpu(cpu) { + struct perf_cpu_context *cpuctx; + cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu); + cpuctx->hrtimer_interval = ns_to_ktime(NSEC_PER_MSEC * timer); + } + + return count; +} + +#define __ATTR_RW(attr) __ATTR(attr, 0644, attr##_show, attr##_store) + static struct device_attribute pmu_dev_attrs[] = { - __ATTR_RO(type), - __ATTR_NULL, + __ATTR_RO(type), + __ATTR_RW(mux_interval_ms), + __ATTR_NULL, }; static int pmu_bus_running; -- 1.7.5.4
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