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Subject[PATCH 1/3] sched: Out-of-line task_rq_lock()
Its a rather large function, inline doesn't seems to make much sense.

$ size defconfig-build/kernel/sched/core.o{.orig,}
text data bss dec hex filename
56533 21037 2320 79890 13812 defconfig-build/kernel/sched/core.o.orig
55733 21037 2320 79090 134f2 defconfig-build/kernel/sched/core.o

$ for i in /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor ; do echo performance > $i ; done
$ perf stat --null --repeat 25 -- perf bench sched messaging -g 40 -l 5000

pre:
4.582798193 seconds time elapsed ( +- 1.41% )
4.733374877 seconds time elapsed ( +- 2.10% )
4.560955136 seconds time elapsed ( +- 1.43% )
4.631062303 seconds time elapsed ( +- 1.40% )

post:
4.364765213 seconds time elapsed ( +- 0.91% )
4.454442734 seconds time elapsed ( +- 1.18% )
4.448893817 seconds time elapsed ( +- 1.41% )
4.424346872 seconds time elapsed ( +- 0.97% )

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -170,6 +170,71 @@ static struct rq *this_rq_lock(void)
return rq;
}

+/*
+ * __task_rq_lock - lock the rq @p resides on.
+ */
+struct rq *__task_rq_lock(struct task_struct *p)
+ __acquires(rq->lock)
+{
+ struct rq *rq;
+
+ lockdep_assert_held(&p->pi_lock);
+
+ for (;;) {
+ rq = task_rq(p);
+ raw_spin_lock(&rq->lock);
+ if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) {
+ lockdep_pin_lock(&rq->lock);
+ return rq;
+ }
+ raw_spin_unlock(&rq->lock);
+
+ while (unlikely(task_on_rq_migrating(p)))
+ cpu_relax();
+ }
+}
+
+/*
+ * task_rq_lock - lock p->pi_lock and lock the rq @p resides on.
+ */
+struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags)
+ __acquires(p->pi_lock)
+ __acquires(rq->lock)
+{
+ struct rq *rq;
+
+ for (;;) {
+ raw_spin_lock_irqsave(&p->pi_lock, *flags);
+ rq = task_rq(p);
+ raw_spin_lock(&rq->lock);
+ /*
+ * move_queued_task() task_rq_lock()
+ *
+ * ACQUIRE (rq->lock)
+ * [S] ->on_rq = MIGRATING [L] rq = task_rq()
+ * WMB (__set_task_cpu()) ACQUIRE (rq->lock);
+ * [S] ->cpu = new_cpu [L] task_rq()
+ * [L] ->on_rq
+ * RELEASE (rq->lock)
+ *
+ * If we observe the old cpu in task_rq_lock, the acquire of
+ * the old rq->lock will fully serialize against the stores.
+ *
+ * If we observe the new cpu in task_rq_lock, the acquire will
+ * pair with the WMB to ensure we must then also see migrating.
+ */
+ if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) {
+ lockdep_pin_lock(&rq->lock);
+ return rq;
+ }
+ raw_spin_unlock(&rq->lock);
+ raw_spin_unlock_irqrestore(&p->pi_lock, *flags);
+
+ while (unlikely(task_on_rq_migrating(p)))
+ cpu_relax();
+ }
+}
+
#ifdef CONFIG_SCHED_HRTICK
/*
* Use HR-timers to deliver accurate preemption points.
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1451,70 +1451,11 @@ static inline void sched_rt_avg_update(s
static inline void sched_avg_update(struct rq *rq) { }
#endif

-/*
- * __task_rq_lock - lock the rq @p resides on.
- */
-static inline struct rq *__task_rq_lock(struct task_struct *p)
- __acquires(rq->lock)
-{
- struct rq *rq;
-
- lockdep_assert_held(&p->pi_lock);
-
- for (;;) {
- rq = task_rq(p);
- raw_spin_lock(&rq->lock);
- if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) {
- lockdep_pin_lock(&rq->lock);
- return rq;
- }
- raw_spin_unlock(&rq->lock);
-
- while (unlikely(task_on_rq_migrating(p)))
- cpu_relax();
- }
-}
-
-/*
- * task_rq_lock - lock p->pi_lock and lock the rq @p resides on.
- */
-static inline struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags)
+struct rq *__task_rq_lock(struct task_struct *p)
+ __acquires(rq->lock);
+struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags)
__acquires(p->pi_lock)
- __acquires(rq->lock)
-{
- struct rq *rq;
-
- for (;;) {
- raw_spin_lock_irqsave(&p->pi_lock, *flags);
- rq = task_rq(p);
- raw_spin_lock(&rq->lock);
- /*
- * move_queued_task() task_rq_lock()
- *
- * ACQUIRE (rq->lock)
- * [S] ->on_rq = MIGRATING [L] rq = task_rq()
- * WMB (__set_task_cpu()) ACQUIRE (rq->lock);
- * [S] ->cpu = new_cpu [L] task_rq()
- * [L] ->on_rq
- * RELEASE (rq->lock)
- *
- * If we observe the old cpu in task_rq_lock, the acquire of
- * the old rq->lock will fully serialize against the stores.
- *
- * If we observe the new cpu in task_rq_lock, the acquire will
- * pair with the WMB to ensure we must then also see migrating.
- */
- if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) {
- lockdep_pin_lock(&rq->lock);
- return rq;
- }
- raw_spin_unlock(&rq->lock);
- raw_spin_unlock_irqrestore(&p->pi_lock, *flags);
-
- while (unlikely(task_on_rq_migrating(p)))
- cpu_relax();
- }
-}
+ __acquires(rq->lock);

static inline void __task_rq_unlock(struct rq *rq)
__releases(rq->lock)

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