tracing/sched: Add sched_pi_setprio tracepoint

Add a tracepoint that shows the priority of a task being boosted
via priority inheritance.

Cc: Gregory Haskins <ghaskins@novell.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

2 files changed, 30 insertions, 0 deletions

diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index 9208c92aeab5..f6334782a593 100644
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h
@@ -362,6 +362,35 @@ TRACE_EVENT(sched_stat_runtime,
                         (unsigned long long)__entry->vruntime)
 );
 
+/*
+ * Tracepoint for showing priority inheritance modifying a tasks
+ * priority.
+ */
+TRACE_EVENT(sched_pi_setprio,
+
+        TP_PROTO(struct task_struct *tsk, int newprio),
+
+        TP_ARGS(tsk, newprio),
+
+        TP_STRUCT__entry(
+                __array( char,  comm,   TASK_COMM_LEN   )
+                __field( pid_t, pid                     )
+                __field( int,   oldprio                 )
+                __field( int,   newprio                 )
+        ),
+
+        TP_fast_assign(
+                memcpy(__entry->comm, tsk->comm, TASK_COMM_LEN);
+                __entry->pid            = tsk->pid;
+                __entry->oldprio        = tsk->prio;
+                __entry->newprio        = newprio;
+        ),
+
+        TP_printk("comm=%s pid=%d oldprio=%d newprio=%d",
+                        __entry->comm, __entry->pid,
+                        __entry->oldprio, __entry->newprio)
+);
+
 #endif /* _TRACE_SCHED_H */
 
 /* This part must be outside protection */
diff --git a/kernel/sched.c b/kernel/sched.c
index 9ca8ad05950b..4ad473814350 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4355,6 +4355,7 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
 
         rq = task_rq_lock(p, &flags);
 
+        trace_sched_pi_setprio(p, prio);
         oldprio = p->prio;
         prev_class = p->sched_class;
         on_rq = p->se.on_rq;