linux-kernel - [PATCH] sched/pelt: fix update of blocked pelt ordering

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Date:   Wed, 30 Oct 2019 12:18:29 +0100
From:   Vincent Guittot <vincent.guittot@...aro.org>
To:     linux-kernel@...r.kernel.org, mingo@...hat.com,
        peterz@...radead.org, dietmar.eggemann@....com,
        juri.lelli@...hat.com, rostedt@...dmis.org, mgorman@...e.de
Cc:     dsmythies@...us.net, Vincent Guittot <vincent.guittot@...aro.org>
Subject: [PATCH] sched/pelt: fix update of blocked pelt ordering

update_cfs_rq_load_avg() can call cpufreq_update_util() to trigger an
update of the frequency. Make sure that RT, DL and IRQ pelt signals have
been updated before calling cpufreq

Fixes: 371bf4273269 ("sched/rt: Add rt_rq utilization tracking")
Fixes: 3727e0e16340 ("sched/dl: Add dl_rq utilization tracking")
Fixes: 91c27493e78d ("sched/irq: Add IRQ utilization tracking")
Signed-off-by: Vincent Guittot <vincent.guittot@...aro.org>
---
 kernel/sched/fair.c | 29 ++++++++++++++++++++---------
 1 file changed, 20 insertions(+), 9 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index a144874..adc923f 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -7446,6 +7446,19 @@ static void update_blocked_averages(int cpu)
 	update_rq_clock(rq);
 
 	/*
+	 * update_cfs_rq_load_avg() can call cpufreq_update_util(). Make sure
+	 * that RT, DL and IRQ signals have been updated before updating CFS.
+	 */
+	curr_class = rq->curr->sched_class;
+	update_rt_rq_load_avg(rq_clock_pelt(rq), rq, curr_class == &rt_sched_class);
+	update_dl_rq_load_avg(rq_clock_pelt(rq), rq, curr_class == &dl_sched_class);
+	update_irq_load_avg(rq, 0);
+
+	/* Don't need periodic decay once load/util_avg are null */
+	if (others_have_blocked(rq))
+		done = false;
+
+	/*
 	 * Iterates the task_group tree in a bottom up fashion, see
 	 * list_add_leaf_cfs_rq() for details.
 	 */
@@ -7472,14 +7485,6 @@ static void update_blocked_averages(int cpu)
 			done = false;
 	}
 
-	curr_class = rq->curr->sched_class;
-	update_rt_rq_load_avg(rq_clock_pelt(rq), rq, curr_class == &rt_sched_class);
-	update_dl_rq_load_avg(rq_clock_pelt(rq), rq, curr_class == &dl_sched_class);
-	update_irq_load_avg(rq, 0);
-	/* Don't need periodic decay once load/util_avg are null */
-	if (others_have_blocked(rq))
-		done = false;
-
 	update_blocked_load_status(rq, !done);
 	rq_unlock_irqrestore(rq, &rf);
 }
@@ -7540,12 +7545,18 @@ static inline void update_blocked_averages(int cpu)
 
 	rq_lock_irqsave(rq, &rf);
 	update_rq_clock(rq);
-	update_cfs_rq_load_avg(cfs_rq_clock_pelt(cfs_rq), cfs_rq);
 
+	/*
+	 * update_cfs_rq_load_avg() can call cpufreq_update_util(). Make sure
+	 * that RT, DL and IRQ signals have been updated before updating CFS.
+	 */
 	curr_class = rq->curr->sched_class;
 	update_rt_rq_load_avg(rq_clock_pelt(rq), rq, curr_class == &rt_sched_class);
 	update_dl_rq_load_avg(rq_clock_pelt(rq), rq, curr_class == &dl_sched_class);
 	update_irq_load_avg(rq, 0);
+
+	update_cfs_rq_load_avg(cfs_rq_clock_pelt(cfs_rq), cfs_rq);
+
 	update_blocked_load_status(rq, cfs_rq_has_blocked(cfs_rq) || others_have_blocked(rq));
 	rq_unlock_irqrestore(rq, &rf);
 }
-- 
2.7.4