[PATCH 4/4] sched: add trace event for idle injection

Jacob Pan
2015-11-13T19:54:31Z

Trace events for idle injection can be used to determine
timer activities for checking synchronization. In addition they
also helps to determine when the runqueue is throttled.

Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
---
include/linux/sched.h | 5 +++++
include/trace/events/sched.h | 25 +++++++++++++++++++++++++
kernel/sched/fair.c | 3 +++
3 files changed, 33 insertions(+)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index ff551a3..99c79bf 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -3189,6 +3189,11 @@ extern int proc_sched_cfs_idle_inject_duration_handler(struct ctl_table *table,
int write,
void __user *buffer,
size_t *length, loff_t *ppos);
+enum cfs_idle_inject_action {
+ CFS_IDLE_INJECT_TIMER, /* timer sync point */
+ CFS_IDLE_INJECT_FORCED, /* idle forced in rq */
+ CFS_IDLE_INJECT_YIELD_SOFTIRQ /* yield to pending softirq */
+};
#endif

#endif
diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index 539d6bc..52c11c1 100644
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h
@@ -566,6 +566,31 @@ TRACE_EVENT(sched_wake_idle_without_ipi,

TP_printk("cpu=%d", __entry->cpu)
);
+
+#ifdef CONFIG_CFS_IDLE_INJECT
+/*
+ * Tracepoint for idle injection
+ */
+TRACE_EVENT(sched_cfs_idle_inject,
+
+ TP_PROTO(enum cfs_idle_inject_action action, int throttled),
+
+ TP_ARGS(action, throttled),
+
+ TP_STRUCT__entry(
+ __field(enum cfs_idle_inject_action, action)
+ __field(int, throttled)
+ ),
+
+ TP_fast_assign(
+ __entry->action = action;
+ __entry->throttled = throttled;
+ ),
+
+ TP_printk("action:%d throttled:%d", __entry->action, __entry->throttled)
+);
+#endif
+
#endif /* _TRACE_SCHED_H */

/* This part must be outside protection */
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index a0cd777..20027eb 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5248,8 +5248,10 @@ idle:
if (in_forced_idle(cfs_rq)) {
if (unlikely(local_softirq_pending())) {
__unthrottle_cfs_rq(cfs_rq);
+ trace_sched_cfs_idle_inject(CFS_IDLE_INJECT_YIELD_SOFTIRQ, 1);
goto again;
}
+ trace_sched_cfs_idle_inject(CFS_IDLE_INJECT_FORCED, 1);
return NULL;
}
/*
@@ -8432,6 +8434,7 @@ static enum hrtimer_restart idle_inject_timer_fn(struct hrtimer *hrtimer)
throttle_rq(cpu);
}
raw_cpu_write(idle_injected, !status);
+ trace_sched_cfs_idle_inject(CFS_IDLE_INJECT_TIMER, !status);

return HRTIMER_RESTART;
}
--
1.9.1