linux-kernel - [GIT PULL] scheduler fixes

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Date:   Fri, 21 Jul 2017 12:18:31 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     linux-kernel@...r.kernel.org,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: [GIT PULL] scheduler fixes

Linus,

Please pull the latest sched-urgent-for-linus git tree from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched-urgent-for-linus

   # HEAD: 193be41e33168a3a06eb9d356d9e39c69de161d2 sched/deadline: Fix confusing comments about selection of top pi-waiter

A cputime fix and code comments/organization fix to the deadline scheduler.

 Thanks,

	Ingo

------------------>
Joel Fernandes (1):
      sched/deadline: Fix confusing comments about selection of top pi-waiter

Wanpeng Li (1):
      sched/cputime: Don't use smp_processor_id() in preemptible context


 kernel/sched/cputime.c  |  6 +++---
 kernel/sched/deadline.c | 14 ++++++++------
 2 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 6e3ea4ac1bda..14d2dbf97c53 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -683,7 +683,7 @@ static u64 vtime_delta(struct vtime *vtime)
 {
 	unsigned long long clock;
 
-	clock = sched_clock_cpu(smp_processor_id());
+	clock = sched_clock();
 	if (clock < vtime->starttime)
 		return 0;
 
@@ -814,7 +814,7 @@ void arch_vtime_task_switch(struct task_struct *prev)
 
 	write_seqcount_begin(&vtime->seqcount);
 	vtime->state = VTIME_SYS;
-	vtime->starttime = sched_clock_cpu(smp_processor_id());
+	vtime->starttime = sched_clock();
 	write_seqcount_end(&vtime->seqcount);
 }
 
@@ -826,7 +826,7 @@ void vtime_init_idle(struct task_struct *t, int cpu)
 	local_irq_save(flags);
 	write_seqcount_begin(&vtime->seqcount);
 	vtime->state = VTIME_SYS;
-	vtime->starttime = sched_clock_cpu(cpu);
+	vtime->starttime = sched_clock();
 	write_seqcount_end(&vtime->seqcount);
 	local_irq_restore(flags);
 }
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index a84299f44b5d..755bd3f1a1a9 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1392,17 +1392,19 @@ static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags)
 	struct sched_dl_entity *pi_se = &p->dl;
 
 	/*
-	 * Use the scheduling parameters of the top pi-waiter
-	 * task if we have one and its (absolute) deadline is
-	 * smaller than our one... OTW we keep our runtime and
-	 * deadline.
+	 * Use the scheduling parameters of the top pi-waiter task if:
+	 * - we have a top pi-waiter which is a SCHED_DEADLINE task AND
+	 * - our dl_boosted is set (i.e. the pi-waiter's (absolute) deadline is
+	 *   smaller than our deadline OR we are a !SCHED_DEADLINE task getting
+	 *   boosted due to a SCHED_DEADLINE pi-waiter).
+	 * Otherwise we keep our runtime and deadline.
 	 */
-	if (pi_task && p->dl.dl_boosted && dl_prio(pi_task->normal_prio)) {
+	if (pi_task && dl_prio(pi_task->normal_prio) && p->dl.dl_boosted) {
 		pi_se = &pi_task->dl;
 	} else if (!dl_prio(p->normal_prio)) {
 		/*
 		 * Special case in which we have a !SCHED_DEADLINE task
-		 * that is going to be deboosted, but exceedes its
+		 * that is going to be deboosted, but exceeds its
 		 * runtime while doing so. No point in replenishing
 		 * it, as it's going to return back to its original
 		 * scheduling class after this.