linux-kernel - [PATCH 2/2] sched/deadline: rq_{online,offline}_dl for root

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Date:	Mon,  8 Feb 2016 12:45:31 +0000
From:	Juri Lelli <juri.lelli@....com>
To:	rostedt@...dmis.org
Cc:	linux-kernel@...r.kernel.org, peterz@...radead.org,
	mingo@...hat.com, luca.abeni@...tn.it, vincent.guittot@...aro.org,
	wanpeng.li@...mail.com, juri.lelli@....com
Subject: [PATCH 2/2] sched/deadline: rq_{online,offline}_dl for root_domain changes

Steven Rostedt reported that we lose information about the amount of
bandwidth that has been admitted to the system across operations that
reconfigure scheduling domains (and are thus destructive w.r.t. root
domains). Wanpeng Li also previously reported a similar problem related
to hotplug, but, since hotplug operations entail scheduling domains
reconfiguration, we can fix both problems at once.

This patch leverages per-rq admitted bandwidth information introduced by
previous commit and couple that with rq_{online,offline}_dl calls to
save and restore root_domain state across scheduling domains
reconfiguration.

Cc: Ingo Molnar <mingo@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Reported-by: Wanpeng Li <wanpeng.li@...mail.com>
Reported-by: Steven Rostedt <rostedt@...dmis.org>
Signed-off-by: Juri Lelli <juri.lelli@....com>
---
 kernel/sched/deadline.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 2480cab..925814e 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1683,6 +1683,7 @@ static void rq_online_dl(struct rq *rq)
 	if (rq->dl.overloaded)
 		dl_set_overload(rq);

+	__dl_add(&rq->rd->dl_bw, rq->dl.ac_bw);
 	cpudl_set_freecpu(&rq->rd->cpudl, rq->cpu);
 	if (rq->dl.dl_nr_running > 0)
 		cpudl_set(&rq->rd->cpudl, rq->cpu, rq->dl.earliest_dl.curr, 1);
@@ -1696,6 +1697,7 @@ static void rq_offline_dl(struct rq *rq)

 	cpudl_set(&rq->rd->cpudl, rq->cpu, 0, 0);
 	cpudl_clear_freecpu(&rq->rd->cpudl, rq->cpu);
+	__dl_clear(&rq->rd->dl_bw, rq->dl.ac_bw);
 }

 void __init init_sched_dl_class(void)
-- 
2.7.0