linux-kernel - [RFC 38/60] cosched: Skip updates on non-CPU runqueues in cfs_rq_util

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Date:   Fri,  7 Sep 2018 23:40:25 +0200
From:   Jan H. Schönherr <jschoenh@...zon.de>
To:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     Jan H. Schönherr <jschoenh@...zon.de>,
        linux-kernel@...r.kernel.org
Subject: [RFC 38/60] cosched: Skip updates on non-CPU runqueues in cfs_rq_util_change()

The function cfs_rq_util_change() notifies frequency governors of
utilization changes, so that they can be scheduler driven. This is
coupled to per CPU runqueue statistics. So, don't do anything
when called for non-CPU runqueues.

Signed-off-by: Jan H. Schönherr <jschoenh@...zon.de>
---
 kernel/sched/fair.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index a2945355f823..33e3f759eb99 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3015,7 +3015,16 @@ static inline void update_cfs_group(struct sched_entity *se)
 
 static inline void cfs_rq_util_change(struct cfs_rq *cfs_rq, int flags)
 {
-	struct rq *rq = rq_of(cfs_rq);
+	struct rq *rq = hrq_of(cfs_rq);
+
+#ifdef CONFIG_COSCHEDULING
+	/*
+	 * This function is currently only well defined for per-CPU
+	 * runqueues. Don't execute it for anything else.
+	 */
+	if (rq->sdrq_data.level)
+		return;
+#endif
 
 	if (&rq->cfs == cfs_rq || (flags & SCHED_CPUFREQ_MIGRATION)) {
 		/*
-- 
2.9.3.1.gcba166c.dirty