events, sched: Add tracepoint for accounting blocked time

This tracepoint shows how long a task is sleeping in uninterruptible state.

E.g. it may show how long and where a mutex is waited for.

Signed-off-by: Andrew Vagin <avagin@openvz.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1322471015-107825-8-git-send-email-avagin@openvz.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 9 insertions, 0 deletions

diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index 959ff18b63b..e33ed1bfa11 100644
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h
@@ -331,6 +331,13 @@ DEFINE_EVENT(sched_stat_template, sched_stat_iowait,
              TP_ARGS(tsk, delay));
 
 /*
+ * Tracepoint for accounting blocked time (time the task is in uninterruptible).
+ */
+DEFINE_EVENT(sched_stat_template, sched_stat_blocked,
+             TP_PROTO(struct task_struct *tsk, u64 delay),
+             TP_ARGS(tsk, delay));
+
+/*
  * Tracepoint for accounting runtime (time the task is executing
  * on a CPU).
  */
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index cd3b64219d9..7c62e2bf234 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1030,6 +1030,8 @@ static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
                                 trace_sched_stat_iowait(tsk, delta);
                         }
 
+                        trace_sched_stat_blocked(tsk, delta);
+
                         /*
                          * Blocking time is in units of nanosecs, so shift by
                          * 20 to get a milliseconds-range estimation of the