Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler updates from Ingo Molnar:

 - Move the nohz kick code out of the scheduler tick to a dedicated IPI,
   from Frederic Weisbecker.

  This necessiated quite some background infrastructure rework,
  including:

   * Clean up some irq-work internals
   * Implement remote irq-work
   * Implement nohz kick on top of remote irq-work
   * Move full dynticks timer enqueue notification to new kick
   * Move multi-task notification to new kick
   * Remove unecessary barriers on multi-task notification

 - Remove proliferation of wait_on_bit() action functions and allow
   wait_on_bit_action() functions to support a timeout.  (Neil Brown)

 - Another round of sched/numa improvements, cleanups and fixes.  (Rik
   van Riel)

 - Implement fast idling of CPUs when the system is partially loaded,
   for better scalability.  (Tim Chen)

 - Restructure and fix the CPU hotplug handling code that may leave
   cfs_rq and rt_rq's throttled when tasks are migrated away from a dead
   cpu.  (Kirill Tkhai)

 - Robustify the sched topology setup code.  (Peterz Zijlstra)

 - Improve sched_feat() handling wrt.  static_keys (Jason Baron)

 - Misc fixes.

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (37 commits)
  sched/fair: Fix 'make xmldocs' warning caused by missing description
  sched: Use macro for magic number of -1 for setparam
  sched: Robustify topology setup
  sched: Fix sched_setparam() policy == -1 logic
  sched: Allow wait_on_bit_action() functions to support a timeout
  sched: Remove proliferation of wait_on_bit() action functions
  sched/numa: Revert "Use effective_load() to balance NUMA loads"
  sched: Fix static_key race with sched_feat()
  sched: Remove extra static_key*() function indirection
  sched/rt: Fix replenish_dl_entity() comments to match the current upstream code
  sched: Transform resched_task() into resched_curr()
  sched/deadline: Kill task_struct->pi_top_task
  sched: Rework check_for_tasks()
  sched/rt: Enqueue just unthrottled rt_rq back on the stack in __disable_runtime()
  sched/fair: Disable runtime_enabled on dying rq
  sched/numa: Change scan period code to match intent
  sched/numa: Rework best node setting in task_numa_migrate()
  sched/numa: Examine a task move when examining a task swap
  sched/numa: Simplify task_numa_compare()
  sched/numa: Use effective_load() to balance NUMA loads
  ...

1 files changed, 21 insertions, 17 deletions

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 31cc02ebc54..579712f4e9d 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -477,6 +477,9 @@ struct root_domain {
 	cpumask_var_t span;
 	cpumask_var_t online;
 
+	/* Indicate more than one runnable task for any CPU */
+	bool overload;
+
 	/*
 	 * The bit corresponding to a CPU gets set here if such CPU has more
 	 * than one runnable -deadline task (as it is below for RT tasks).
@@ -884,20 +887,10 @@ enum {
 #undef SCHED_FEAT
 
 #if defined(CONFIG_SCHED_DEBUG) && defined(HAVE_JUMP_LABEL)
-static __always_inline bool static_branch__true(struct static_key *key)
-{
-	return static_key_true(key); /* Not out of line branch. */
-}
-
-static __always_inline bool static_branch__false(struct static_key *key)
-{
-	return static_key_false(key); /* Out of line branch. */
-}
-
 #define SCHED_FEAT(name, enabled)					\
 static __always_inline bool static_branch_##name(struct static_key *key) \
 {									\
-	return static_branch__##enabled(key);				\
+	return static_key_##enabled(key);				\
 }
 
 #include "features.h"
@@ -1196,7 +1189,7 @@ extern void init_sched_rt_class(void);
 extern void init_sched_fair_class(void);
 extern void init_sched_dl_class(void);
 
-extern void resched_task(struct task_struct *p);
+extern void resched_curr(struct rq *rq);
 extern void resched_cpu(int cpu);
 
 extern struct rt_bandwidth def_rt_bandwidth;
@@ -1218,15 +1211,26 @@ static inline void add_nr_running(struct rq *rq, unsigned count)
 
 	rq->nr_running = prev_nr + count;
 
-#ifdef CONFIG_NO_HZ_FULL
 	if (prev_nr < 2 && rq->nr_running >= 2) {
+#ifdef CONFIG_SMP
+		if (!rq->rd->overload)
+			rq->rd->overload = true;
+#endif
+
+#ifdef CONFIG_NO_HZ_FULL
 		if (tick_nohz_full_cpu(rq->cpu)) {
-			/* Order rq->nr_running write against the IPI */
-			smp_wmb();
-			smp_send_reschedule(rq->cpu);
+			/*
+			 * Tick is needed if more than one task runs on a CPU.
+			 * Send the target an IPI to kick it out of nohz mode.
+			 *
+			 * We assume that IPI implies full memory barrier and the
+			 * new value of rq->nr_running is visible on reception
+			 * from the target.
+			 */
+			tick_nohz_full_kick_cpu(rq->cpu);
 		}
-       }
 #endif
+	}
 }
 
 static inline void sub_nr_running(struct rq *rq, unsigned count)