[PATCH] schedstat: fix schedule() statistics

[Akinobu Mita]

Hello,

The number of times schedule() left the processor idle in the /proc/schedstat
(runqueue.sched_goidle) seems to be wrong.

The schedule() statistics should satisfy the equation:
	sched_cnt == sched_noswitch + sched_switch + sched_goidle

(http://eaglet.rain.com/rick/linux/schedstat/v10/format-10.html)

The below patch fix this, and I have confirmed to be fixed with:
	# grep ^cpu /proc/schedstat | awk '{print $6+$7+$9, $8}'

--- 2.6-mm/kernel/sched.c.orig	2004-10-22 01:09:38.391429584 +0900
+++ 2.6-mm/kernel/sched.c	2004-10-22 01:23:18.590740336 +0900
@@ -2809,7 +2809,6 @@ go_idle:
 		}
 	} else {
 		if (dependent_sleeper(cpu, rq)) {
-			schedstat_inc(rq, sched_goidle);
 			next = rq->idle;
 			goto switch_tasks;
 		}
@@ -2853,6 +2852,8 @@ go_idle:
 	}
 	next->activated = 0;
 switch_tasks:
+	if (next == rq->idle)
+		schedstat_inc(rq, sched_goidle);
 	prefetch(next);
 	clear_tsk_need_resched(prev);
 	rcu_qsctr_inc(task_cpu(prev));



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