linux-kernel - [patch 08/10] sched: Add update_migratory() callback to scheduler classes

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Date:   Thu, 17 Sep 2020 11:42:10 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Sebastian Siewior <bigeasy@...utronix.de>,
        Qais Yousef <qais.yousef@....com>,
        Scott Wood <swood@...hat.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Valentin Schneider <valentin.schneider@....com>,
        Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Vincent Donnefort <vincent.donnefort@....com>
Subject: [patch 08/10] sched: Add update_migratory() callback to scheduler classes

Provide a mechanism to update the number or migratory tasks in the RT and
deadline scheduler classes.

This will be used by the upcoming migrate_disable/enable() functionality on
RT kernels.

Originally-by: Daniel Bristot de Oliveira <bristot@...hat.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 kernel/sched/deadline.c |   10 ++++++++++
 kernel/sched/rt.c       |   10 ++++++++++
 kernel/sched/sched.h    |    4 ++++
 3 files changed, 24 insertions(+)

--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -479,6 +479,13 @@ static void dec_dl_migration(struct sche
 	update_dl_migration(dl_rq);
 }
 
+#ifdef CONFIG_PREEMPT_RT
+static void update_migratory_dl(struct task_struct *p, long delta)
+{
+	task_rq(p)->dl.dl_nr_migratory += delta;
+}
+#endif
+
 /*
  * The list of pushable -deadline task is not a plist, like in
  * sched_rt.c, it is an rb-tree with tasks ordered by deadline.
@@ -2499,6 +2506,9 @@ const struct sched_class dl_sched_class
 	.rq_online              = rq_online_dl,
 	.rq_offline             = rq_offline_dl,
 	.task_woken		= task_woken_dl,
+#ifdef CONFIG_PREEMPT_RT
+	.update_migratory	= update_migratory_dl,
+#endif
 #endif
 
 	.task_tick		= task_tick_dl,
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -2272,6 +2272,13 @@ static void switched_from_rt(struct rq *
 	rt_queue_pull_task(rq);
 }
 
+#ifdef CONFIG_PREEMPT_RT
+static void update_migratory_rt(struct task_struct *p, long delta)
+{
+	task_rq(p)->rt.rt_nr_migratory += delta;
+}
+#endif
+
 void __init init_sched_rt_class(void)
 {
 	unsigned int i;
@@ -2449,6 +2456,9 @@ const struct sched_class rt_sched_class
 	.rq_offline             = rq_offline_rt,
 	.task_woken		= task_woken_rt,
 	.switched_from		= switched_from_rt,
+#ifdef CONFIG_PREEMPT_RT
+	.update_migratory	= update_migratory_rt,
+#endif
 #endif
 
 	.task_tick		= task_tick_rt,
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1808,6 +1808,10 @@ struct sched_class {
 	void (*set_cpus_allowed)(struct task_struct *p,
 				 const struct cpumask *newmask);
 
+#ifdef CONFIG_PREEMPT_RT
+	void (*update_migratory)(struct task_struct *p, long delta);
+#endif
+
 	void (*rq_online)(struct rq *rq);
 	void (*rq_offline)(struct rq *rq);
 #endif