1 files changed, 20 insertions, 21 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index 2b2b780939c..15ce772a471 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -225,7 +225,8 @@ struct rq {
 	unsigned long nr_uninterruptible;
 
 	unsigned long expired_timestamp;
-	unsigned long long timestamp_last_tick;
+	/* Cached timestamp set by update_cpu_clock() */
+	unsigned long long most_recent_timestamp;
 	struct task_struct *curr, *idle;
 	unsigned long next_balance;
 	struct mm_struct *prev_mm;
@@ -944,8 +945,8 @@ static void activate_task(struct task_struct *p, struct rq *rq, int local)
 	if (!local) {
 		/* Compensate for drifting sched_clock */
 		struct rq *this_rq = this_rq();
-		now = (now - this_rq->timestamp_last_tick)
-			+ rq->timestamp_last_tick;
+		now = (now - this_rq->most_recent_timestamp)
+			+ rq->most_recent_timestamp;
 	}
 #endif
 
@@ -1689,8 +1690,8 @@ void fastcall wake_up_new_task(struct task_struct *p, unsigned long clone_flags)
 		 * Not the local CPU - must adjust timestamp. This should
 		 * get optimised away in the !CONFIG_SMP case.
 		 */
-		p->timestamp = (p->timestamp - this_rq->timestamp_last_tick)
-					+ rq->timestamp_last_tick;
+		p->timestamp = (p->timestamp - this_rq->most_recent_timestamp)
+					+ rq->most_recent_timestamp;
 		__activate_task(p, rq);
 		if (TASK_PREEMPTS_CURR(p, rq))
 			resched_task(rq->curr);
@@ -2068,8 +2069,8 @@ static void pull_task(struct rq *src_rq, struct prio_array *src_array,
 	set_task_cpu(p, this_cpu);
 	inc_nr_running(p, this_rq);
 	enqueue_task(p, this_array);
-	p->timestamp = (p->timestamp - src_rq->timestamp_last_tick)
-				+ this_rq->timestamp_last_tick;
+	p->timestamp = (p->timestamp - src_rq->most_recent_timestamp)
+				+ this_rq->most_recent_timestamp;
 	/*
 	 * Note that idle threads have a prio of MAX_PRIO, for this test
 	 * to be always true for them.
@@ -2105,10 +2106,15 @@ int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu,
 	 * 2) too many balance attempts have failed.
 	 */
 
-	if (sd->nr_balance_failed > sd->cache_nice_tries)
+	if (sd->nr_balance_failed > sd->cache_nice_tries) {
+#ifdef CONFIG_SCHEDSTATS
+		if (task_hot(p, rq->most_recent_timestamp, sd))
+			schedstat_inc(sd, lb_hot_gained[idle]);
+#endif
 		return 1;
+	}
 
-	if (task_hot(p, rq->timestamp_last_tick, sd))
+	if (task_hot(p, rq->most_recent_timestamp, sd))
 		return 0;
 	return 1;
 }
@@ -2206,11 +2212,6 @@ skip_queue:
 		goto skip_bitmap;
 	}
 
-#ifdef CONFIG_SCHEDSTATS
-	if (task_hot(tmp, busiest->timestamp_last_tick, sd))
-		schedstat_inc(sd, lb_hot_gained[idle]);
-#endif
-
 	pull_task(busiest, array, tmp, this_rq, dst_array, this_cpu);
 	pulled++;
 	rem_load_move -= tmp->load_weight;
@@ -2971,7 +2972,8 @@ EXPORT_PER_CPU_SYMBOL(kstat);
 static inline void
 update_cpu_clock(struct task_struct *p, struct rq *rq, unsigned long long now)
 {
-	p->sched_time += now - max(p->timestamp, rq->timestamp_last_tick);
+	p->sched_time += now - p->last_ran;
+	p->last_ran = rq->most_recent_timestamp = now;
 }
 
 /*
@@ -2984,8 +2986,7 @@ unsigned long long current_sched_time(const struct task_struct *p)
 	unsigned long flags;
 
 	local_irq_save(flags);
-	ns = max(p->timestamp, task_rq(p)->timestamp_last_tick);
-	ns = p->sched_time + sched_clock() - ns;
+	ns = p->sched_time + sched_clock() - p->last_ran;
 	local_irq_restore(flags);
 
 	return ns;
@@ -3176,8 +3177,6 @@ void scheduler_tick(void)
 
 	update_cpu_clock(p, rq, now);
 
-	rq->timestamp_last_tick = now;
-
 	if (p == rq->idle)
 		/* Task on the idle queue */
 		wake_priority_sleeper(rq);
@@ -5032,8 +5031,8 @@ static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
 		 * afterwards, and pretending it was a local activate.
 		 * This way is cleaner and logically correct.
 		 */
-		p->timestamp = p->timestamp - rq_src->timestamp_last_tick
-				+ rq_dest->timestamp_last_tick;
+		p->timestamp = p->timestamp - rq_src->most_recent_timestamp
+				+ rq_dest->most_recent_timestamp;
 		deactivate_task(p, rq_src);
 		__activate_task(p, rq_dest);
 		if (TASK_PREEMPTS_CURR(p, rq_dest))