1 files changed, 72 insertions, 2 deletions

diff --git a/arch/x86/kernel/cpu/perf_event_intel_rapl.c b/arch/x86/kernel/cpu/perf_event_intel_rapl.c
index cfcd386b5d89..bf8e4a736d48 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_rapl.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_rapl.c
@@ -96,6 +96,8 @@ struct rapl_pmu {
 	int		 n_active; /* number of active events */
 	struct list_head active_list;
 	struct pmu	 *pmu; /* pointer to rapl_pmu_class */
+	ktime_t		 timer_interval; /* in ktime_t unit */
+	struct hrtimer   hrtimer;
 };
 
 static struct pmu rapl_pmu_class;
@@ -158,6 +160,48 @@ again:
 	return new_raw_count;
 }
 
+static void rapl_start_hrtimer(struct rapl_pmu *pmu)
+{
+	__hrtimer_start_range_ns(&pmu->hrtimer,
+			pmu->timer_interval, 0,
+			HRTIMER_MODE_REL_PINNED, 0);
+}
+
+static void rapl_stop_hrtimer(struct rapl_pmu *pmu)
+{
+	hrtimer_cancel(&pmu->hrtimer);
+}
+
+static enum hrtimer_restart rapl_hrtimer_handle(struct hrtimer *hrtimer)
+{
+	struct rapl_pmu *pmu = __get_cpu_var(rapl_pmu);
+	struct perf_event *event;
+	unsigned long flags;
+
+	if (!pmu->n_active)
+		return HRTIMER_NORESTART;
+
+	spin_lock_irqsave(&pmu->lock, flags);
+
+	list_for_each_entry(event, &pmu->active_list, active_entry) {
+		rapl_event_update(event);
+	}
+
+	spin_unlock_irqrestore(&pmu->lock, flags);
+
+	hrtimer_forward_now(hrtimer, pmu->timer_interval);
+
+	return HRTIMER_RESTART;
+}
+
+static void rapl_hrtimer_init(struct rapl_pmu *pmu)
+{
+	struct hrtimer *hr = &pmu->hrtimer;
+
+	hrtimer_init(hr, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	hr->function = rapl_hrtimer_handle;
+}
+
 static void __rapl_pmu_event_start(struct rapl_pmu *pmu,
 				   struct perf_event *event)
 {
@@ -171,6 +215,8 @@ static void __rapl_pmu_event_start(struct rapl_pmu *pmu,
 	local64_set(&event->hw.prev_count, rapl_read_counter(event));
 
 	pmu->n_active++;
+	if (pmu->n_active == 1)
+		rapl_start_hrtimer(pmu);
 }
 
 static void rapl_pmu_event_start(struct perf_event *event, int mode)
@@ -195,6 +241,8 @@ static void rapl_pmu_event_stop(struct perf_event *event, int mode)
 	if (!(hwc->state & PERF_HES_STOPPED)) {
 		WARN_ON_ONCE(pmu->n_active <= 0);
 		pmu->n_active--;
+		if (pmu->n_active == 0)
+			rapl_stop_hrtimer(pmu);
 
 		list_del(&event->active_entry);
 
@@ -423,6 +471,9 @@ static void rapl_cpu_exit(int cpu)
 	 */
 	if (target >= 0)
 		perf_pmu_migrate_context(pmu->pmu, cpu, target);
+
+	/* cancel overflow polling timer for CPU */
+	rapl_stop_hrtimer(pmu);
 }
 
 static void rapl_cpu_init(int cpu)
@@ -442,6 +493,7 @@ static int rapl_cpu_prepare(int cpu)
 {
 	struct rapl_pmu *pmu = per_cpu(rapl_pmu, cpu);
 	int phys_id = topology_physical_package_id(cpu);
+	u64 ms;
 
 	if (pmu)
 		return 0;
@@ -466,6 +518,22 @@ static int rapl_cpu_prepare(int cpu)
 	pmu->hw_unit = (pmu->hw_unit >> 8) & 0x1FULL;
 	pmu->pmu = &rapl_pmu_class;
 
+	/*
+	 * use reference of 200W for scaling the timeout
+	 * to avoid missing counter overflows.
+	 * 200W = 200 Joules/sec
+	 * divide interval by 2 to avoid lockstep (2 * 100)
+	 * if hw unit is 32, then we use 2 ms 1/200/2
+	 */
+	if (pmu->hw_unit < 32)
+		ms = (1000 / (2 * 100)) * (1ULL << (32 - pmu->hw_unit - 1));
+	else
+		ms = 2;
+
+	pmu->timer_interval = ms_to_ktime(ms);
+
+	rapl_hrtimer_init(pmu);
+
 	/* set RAPL pmu for this cpu for now */
 	per_cpu(rapl_pmu, cpu) = pmu;
 	per_cpu(rapl_pmu_to_free, cpu) = NULL;
@@ -580,9 +648,11 @@ static int __init rapl_pmu_init(void)
 
 	pr_info("RAPL PMU detected, hw unit 2^-%d Joules,"
 		" API unit is 2^-32 Joules,"
-		" %d fixed counters\n",
+		" %d fixed counters"
+		" %llu ms ovfl timer\n",
 		pmu->hw_unit,
-		hweight32(rapl_cntr_mask));
+		hweight32(rapl_cntr_mask),
+		ktime_to_ms(pmu->timer_interval));
 
 	put_online_cpus();