[RFC PATCH 02/11] sched: debug spread check account for nr_running

[Mathieu Desnoyers]

Extracted from a "sched-misc-bits.patch" patch from
Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>.

This patch also moves the check_spread test where nr_running is always non-zero.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
CC: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
---
 kernel/sched_fair.c |    9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

Index: linux-2.6-lttng.git/kernel/sched_fair.c
===================================================================
--- linux-2.6-lttng.git.orig/kernel/sched_fair.c
+++ linux-2.6-lttng.git/kernel/sched_fair.c
@@ -715,7 +715,7 @@ static void check_spread(struct cfs_rq *
 	if (d < 0)
 		d = -d;
 
-	if (d > 3*sysctl_sched_latency)
+	if (d > 3*cfs_rq->nr_running*sysctl_sched_latency)
 		schedstat_inc(cfs_rq, nr_spread_over);
 #endif
 }
@@ -803,6 +803,7 @@ dequeue_entity(struct cfs_rq *cfs_rq, st
 	 * Update run-time statistics of the 'current'.
 	 */
 	update_curr(cfs_rq);
+	check_spread(cfs_rq, se);
 
 	update_stats_dequeue(cfs_rq, se);
 	if (flags & DEQUEUE_SLEEP) {
@@ -932,11 +933,9 @@ static void put_prev_entity(struct cfs_r
 	 * If still on the runqueue then deactivate_task()
 	 * was not called and update_curr() has to be done:
 	 */
-	if (prev->on_rq)
-		update_curr(cfs_rq);
-
-	check_spread(cfs_rq, prev);
 	if (prev->on_rq) {
+		update_curr(cfs_rq);
+		check_spread(cfs_rq, prev);
 		update_stats_wait_start(cfs_rq, prev);
 		/* Put 'current' back into the tree. */
 		__enqueue_entity(cfs_rq, prev);

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