rcu: Add tracing to irq/NMI dyntick-idle transitions

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

1 files changed, 8 insertions, 6 deletions

diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h
index 59d40c454aa0..4674b21247f7 100644
--- a/include/trace/events/rcu.h
+++ b/include/trace/events/rcu.h
@@ -421,16 +421,18 @@ TRACE_EVENT(rcu_fqs,
 
 /*
  * Tracepoint for dyntick-idle entry/exit events.  These take a string
- * as argument: "Start" for entering dyntick-idle mode, "End" for
- * leaving it, "--=" for events moving towards idle, and "++=" for events
- * moving away from idle.  "Error on entry: not idle task" and "Error on
- * exit: not idle task" indicate that a non-idle task is erroneously
+ * as argument: "Start" for entering dyntick-idle mode, "Startirq" for
+ * entering it from irq/NMI, "End" for leaving it, "Endirq" for leaving it
+ * to irq/NMI, "--=" for events moving towards idle, and "++=" for events
+ * moving away from idle.  "Error on entry: not idle task" and "Error
+ * on exit: not idle task" indicate that a non-idle task is erroneously
  * toying with the idle loop.
  *
  * These events also take a pair of numbers, which indicate the nesting
  * depth before and after the event of interest.  Note that task-related
- * events use the upper bits of each number, while interrupt-related
- * events use the lower bits.
+ * and interrupt-related events use two separate counters, and that the
+ * "++=" and "--=" events for irq/NMI will change the counter by two,
+ * otherwise by one.
  */
 TRACE_EVENT(rcu_dyntick,