perf: set event period

Change-Id: Ibf569de7af8697e766c10b8d70905b8cdc4df083

arch/arm64/kernel/perfctr.c

@@ -232,3 +232,43 @@ int hw_perf_event_init(struct mc_perf_event *event)
 	}
 	return 0;
 }
+
+int ihk_mc_event_set_period(struct mc_perf_event *event)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	int64_t left = ihk_atomic64_read(&hwc->period_left);
+	int64_t period = hwc->sample_period;
+	uint64_t max_period;
+	int ret = 0;
+
+	max_period = arm_pmu_event_max_period(event);
+	if (unlikely(left <= -period)) {
+		left = period;
+		ihk_atomic64_set(&hwc->period_left, left);
+		hwc->last_period = period;
+		ret = 1;
+	}
+
+	if (unlikely(left <= 0)) {
+		left += period;
+		ihk_atomic64_set(&hwc->period_left, left);
+		hwc->last_period = period;
+		ret = 1;
+	}
+
+	/*
+	 * Limit the maximum period to prevent the counter value
+	 * from overtaking the one we are about to program. In
+	 * effect we are reducing max_period to account for
+	 * interrupt latency (and we are being very conservative).
+	 */
+	if (left > (max_period >> 1))
+		left = (max_period >> 1);
+
+	ihk_atomic64_set(&hwc->prev_count, (uint64_t)-left);
+
+	cpu_pmu.write_counter(event->counter_id,
+			      (uint64_t)(-left) & max_period);
+
+	return ret;
+}

arch/arm64/kernel/perfctr_armv8pmu.c

@@ -788,6 +788,7 @@ static void armv8pmu_handle_irq(void *priv)
 	long irqstate;
 	struct mckfd *fdp;
 	struct pt_regs *regs = (struct pt_regs *)priv;
+	struct mc_perf_event *event = NULL;
 
 	/*
 	 * Get and reset the IRQ flags
@@ -821,6 +822,11 @@ static void armv8pmu_handle_irq(void *priv)
 	else {
 		set_signal(SIGIO, regs, NULL);
 	}
+
+	if (event) {
+		ihk_mc_event_set_period(event);
+	}
+	return;
 }
 
 static void armv8pmu_enable_user_access_pmu_regs(void)

arch/x86_64/kernel/perfctr.c

@@ -508,3 +508,8 @@ int hw_perf_event_init(struct mc_perf_event *event)
 {
 	return 0;
 }
+
+int ihk_mc_event_set_period(struct mc_perf_event *event)
+{
+	return 0;
+}

kernel/syscall.c

@@ -4068,6 +4068,7 @@ void perf_start(struct mc_perf_event *event)
 			leader->base_system_tsc = thread->system_tsc;
 		}
 		else {
+			ihk_mc_event_set_period(leader);
 			perf_counter_set(leader);
 			counter_mask |= 1UL << counter_id;
 		}
@@ -4097,6 +4098,7 @@ void perf_start(struct mc_perf_event *event)
 				sub->base_system_tsc = thread->system_tsc;
 			}
 			else {
+				ihk_mc_event_set_period(sub);
 				perf_counter_set(sub);
 				counter_mask |= 1UL << counter_id;
 			}

lib/include/ihk/cpu.h

@@ -91,6 +91,7 @@ unsigned long ihk_mc_hw_cache_extra_reg_map(unsigned long hw_cache_event);
 unsigned long ihk_mc_raw_event_map(unsigned long raw_event);
 int ihk_mc_validate_event(unsigned long hw_config);
 int hw_perf_event_init(struct mc_perf_event *event);
+int ihk_mc_event_set_period(struct mc_perf_event *event);
 
 static inline int is_sampling_event(struct mc_perf_event *event)
 {