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-rw-r--r--kernel/perf_event.c19
1 files changed, 15 insertions, 4 deletions
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 999835b..656222f 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -782,6 +782,10 @@ retry:
raw_spin_unlock_irq(&ctx->lock);
}
+#define MAX_INTERRUPTS (~0ULL)
+
+static void perf_log_throttle(struct perf_event *event, int enable);
+
static int
event_sched_in(struct perf_event *event,
struct perf_cpu_context *cpuctx,
@@ -794,6 +798,17 @@ event_sched_in(struct perf_event *event,
event->state = PERF_EVENT_STATE_ACTIVE;
event->oncpu = smp_processor_id();
+
+ /*
+ * Unthrottle events, since we scheduled we might have missed several
+ * ticks already, also for a heavily scheduling task there is little
+ * guarantee it'll get a tick in a timely manner.
+ */
+ if (unlikely(event->hw.interrupts == MAX_INTERRUPTS)) {
+ perf_log_throttle(event, 1);
+ event->hw.interrupts = 0;
+ }
+
/*
* The new state must be visible before we turn it on in the hardware:
*/
@@ -1596,10 +1611,6 @@ void __perf_event_task_sched_in(struct task_struct *task)
}
}
-#define MAX_INTERRUPTS (~0ULL)
-
-static void perf_log_throttle(struct perf_event *event, int enable);
-
static u64 perf_calculate_period(struct perf_event *event, u64 nsec, u64 count)
{
u64 frequency = event->attr.sample_freq;
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