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authorPeter Zijlstra <peterz@infradead.org>2019-11-08 16:16:00 +0300
committerIngo Molnar <mingo@kernel.org>2019-11-11 10:35:21 +0300
commita0e813f26ebcb25c0b5e504498fbd796cca1a4ba (patch)
treec6a926cff783866cc5ee1b20ffefb559e78d45fa /kernel/sched/rt.c
parent2eeb01a28c9233333bf229a5b4b0559f4bd22b52 (diff)
downloadlinux-a0e813f26ebcb25c0b5e504498fbd796cca1a4ba.tar.xz
sched/core: Further clarify sched_class::set_next_task()
It turns out there really is something special to the first set_next_task() invocation. In specific the 'change' pattern really should not cause balance callbacks. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: bsegall@google.com Cc: dietmar.eggemann@arm.com Cc: juri.lelli@redhat.com Cc: ktkhai@virtuozzo.com Cc: mgorman@suse.de Cc: qais.yousef@arm.com Cc: qperret@google.com Cc: rostedt@goodmis.org Cc: valentin.schneider@arm.com Cc: vincent.guittot@linaro.org Fixes: f95d4eaee6d0 ("sched/{rt,deadline}: Fix set_next_task vs pick_next_task") Link: https://lkml.kernel.org/r/20191108131909.775434698@infradead.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched/rt.c')
-rw-r--r--kernel/sched/rt.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 38027c04b04c..e591d40fd645 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1515,13 +1515,16 @@ static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p, int flag
#endif
}
-static inline void set_next_task_rt(struct rq *rq, struct task_struct *p)
+static inline void set_next_task_rt(struct rq *rq, struct task_struct *p, bool first)
{
p->se.exec_start = rq_clock_task(rq);
/* The running task is never eligible for pushing */
dequeue_pushable_task(rq, p);
+ if (!first)
+ return;
+
/*
* If prev task was rt, put_prev_task() has already updated the
* utilization. We only care of the case where we start to schedule a
@@ -1572,7 +1575,7 @@ static struct task_struct *pick_next_task_rt(struct rq *rq)
return NULL;
p = _pick_next_task_rt(rq);
- set_next_task_rt(rq, p);
+ set_next_task_rt(rq, p, true);
return p;
}