From 6549841b2ffbc45c56414c3e1ce6046c6d2e3bbd Mon Sep 17 00:00:00 2001
From: Ankita Garg <ankita@in.ibm.com>
Date: Tue, 1 Jul 2008 14:30:06 +0530
Subject: [PATCH] --- yaml --- r: 100249 b: refs/heads/master c:
 46ac22bab42cc868b9c1d0e915ddbc8e8065a44d h: refs/heads/master i:   100247:
 ee0b5a744f89c1a452e1bd4adfd884938971dd2c v: v3

---
 [refs]                     |  2 +-
 trunk/kernel/sched.c       |  1 +
 trunk/kernel/sched_stats.h | 42 ++++++++++++++++++++++++++++++--------
 3 files changed, 35 insertions(+), 10 deletions(-)

diff --git a/[refs] b/[refs]
index 2b921cb37c37..8107d6018f91 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 2087a1ad822cd3a68b73338457047fcc54da726b
+refs/heads/master: 46ac22bab42cc868b9c1d0e915ddbc8e8065a44d
diff --git a/trunk/kernel/sched.c b/trunk/kernel/sched.c
index bbc40c3a0657..996bc15196a5 100644
--- a/trunk/kernel/sched.c
+++ b/trunk/kernel/sched.c
@@ -1714,6 +1714,7 @@ static void dequeue_task(struct rq *rq, struct task_struct *p, int sleep)
 		p->se.last_wakeup = 0;
 	}
 
+	sched_info_dequeued(p);
 	p->sched_class->dequeue_task(rq, p, sleep);
 	p->se.on_rq = 0;
 }
diff --git a/trunk/kernel/sched_stats.h b/trunk/kernel/sched_stats.h
index 80179ef7450e..8385d43987e2 100644
--- a/trunk/kernel/sched_stats.h
+++ b/trunk/kernel/sched_stats.h
@@ -118,6 +118,13 @@ rq_sched_info_depart(struct rq *rq, unsigned long long delta)
 	if (rq)
 		rq->rq_sched_info.cpu_time += delta;
 }
+
+static inline void
+rq_sched_info_dequeued(struct rq *rq, unsigned long long delta)
+{
+	if (rq)
+		rq->rq_sched_info.run_delay += delta;
+}
 # define schedstat_inc(rq, field)	do { (rq)->field++; } while (0)
 # define schedstat_add(rq, field, amt)	do { (rq)->field += (amt); } while (0)
 # define schedstat_set(var, val)	do { var = (val); } while (0)
@@ -126,6 +133,9 @@ static inline void
 rq_sched_info_arrive(struct rq *rq, unsigned long long delta)
 {}
 static inline void
+rq_sched_info_dequeued(struct rq *rq, unsigned long long delta)
+{}
+static inline void
 rq_sched_info_depart(struct rq *rq, unsigned long long delta)
 {}
 # define schedstat_inc(rq, field)	do { } while (0)
@@ -134,6 +144,11 @@ rq_sched_info_depart(struct rq *rq, unsigned long long delta)
 #endif
 
 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
+static inline void sched_info_reset_dequeued(struct task_struct *t)
+{
+	t->sched_info.last_queued = 0;
+}
+
 /*
  * Called when a process is dequeued from the active array and given
  * the cpu.  We should note that with the exception of interactive
@@ -143,15 +158,22 @@ rq_sched_info_depart(struct rq *rq, unsigned long long delta)
  * active queue, thus delaying tasks in the expired queue from running;
  * see scheduler_tick()).
  *
- * This function is only called from sched_info_arrive(), rather than
- * dequeue_task(). Even though a task may be queued and dequeued multiple
- * times as it is shuffled about, we're really interested in knowing how
- * long it was from the *first* time it was queued to the time that it
- * finally hit a cpu.
+ * Though we are interested in knowing how long it was from the *first* time a
+ * task was queued to the time that it finally hit a cpu, we call this routine
+ * from dequeue_task() to account for possible rq->clock skew across cpus. The
+ * delta taken on each cpu would annul the skew.
  */
 static inline void sched_info_dequeued(struct task_struct *t)
 {
-	t->sched_info.last_queued = 0;
+	unsigned long long now = task_rq(t)->clock, delta = 0;
+
+	if (unlikely(sched_info_on()))
+		if (t->sched_info.last_queued)
+			delta = now - t->sched_info.last_queued;
+	sched_info_reset_dequeued(t);
+	t->sched_info.run_delay += delta;
+
+	rq_sched_info_dequeued(task_rq(t), delta);
 }
 
 /*
@@ -165,7 +187,7 @@ static void sched_info_arrive(struct task_struct *t)
 
 	if (t->sched_info.last_queued)
 		delta = now - t->sched_info.last_queued;
-	sched_info_dequeued(t);
+	sched_info_reset_dequeued(t);
 	t->sched_info.run_delay += delta;
 	t->sched_info.last_arrival = now;
 	t->sched_info.pcount++;
@@ -242,7 +264,9 @@ sched_info_switch(struct task_struct *prev, struct task_struct *next)
 		__sched_info_switch(prev, next);
 }
 #else
-#define sched_info_queued(t)		do { } while (0)
-#define sched_info_switch(t, next)	do { } while (0)
+#define sched_info_queued(t)			do { } while (0)
+#define sched_info_reset_dequeued(t)	do { } while (0)
+#define sched_info_dequeued(t)			do { } while (0)
+#define sched_info_switch(t, next)		do { } while (0)
 #endif /* CONFIG_SCHEDSTATS || CONFIG_TASK_DELAY_ACCT */