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Subject[PATCH 2/2] sched: Use fair:prio_changed() instead of ad-hoc implementation
Date
set_user_nice() implements its own version of fair::prio_changed() and
therefore misses a specific optimization towards nohz_full CPUs that
avoid sending an resched IPI to a reniced task running alone. Use the
proper callback instead.

Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
kernel/sched/core.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 90e4b00ace89..66d1af94455e 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4540,17 +4540,17 @@ void set_user_nice(struct task_struct *p, long nice)
p->prio = effective_prio(p);
delta = p->prio - old_prio;

- if (queued) {
+ if (queued)
enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK);
- /*
- * If the task increased its priority or is running and
- * lowered its priority, then reschedule its CPU:
- */
- if (delta < 0 || (delta > 0 && task_running(rq, p)))
- resched_curr(rq);
- }
+
if (running)
set_next_task(rq, p);
+ /*
+ * If the task increased its priority or is running and
+ * lowered its priority, then reschedule its CPU:
+ */
+ p->sched_class->prio_changed(rq, p, old_prio);
+
out_unlock:
task_rq_unlock(rq, p, &rf);
}
--
2.23.0
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