Merge pull request raspberrypi#24 from sched-ext/task_on_scx

SCX: s/task_on_scx()/task_should_scx()/ and add new task_on_scx() whi…

Author: Byte-Lab

kernel/sched/core.c

@@ -167,10 +167,8 @@ static inline int __task_prio(const struct task_struct *p)
 	if (p->sched_class == &idle_sched_class)
 		return MAX_RT_PRIO + NICE_WIDTH; /* 140 */
 
-#ifdef CONFIG_SCHED_CLASS_EXT
-	if (p->sched_class == &ext_sched_class)
+	if (task_on_scx(p))
 		return MAX_RT_PRIO + MAX_NICE + 1; /* 120, squash ext */
-#endif
 
 	return MAX_RT_PRIO + MAX_NICE; /* 119, squash fair */
 }
@@ -3954,16 +3952,15 @@ bool cpus_share_cache(int this_cpu, int that_cpu)
 
 static inline bool ttwu_queue_cond(struct task_struct *p, int cpu)
 {
-#ifdef CONFIG_SCHED_CLASS_EXT
 	/*
 	 * The BPF scheduler may depend on select_task_rq() being invoked during
-	 * wakeups and @p may end up executing on a different CPU regardless of
-	 * what happens in the wakeup path making the ttwu_queue optimization
-	 * ineffective. Skip if on SCX.
+	 * wakeups. In addition, @p may end up executing on a different CPU
+	 * regardless of what happens in the wakeup path making the ttwu_queue
+	 * optimization less meaningful. Skip if on SCX.
 	 */
-	if (p->sched_class == &ext_sched_class)
+	if (task_on_scx(p))
 		return false;
-#endif
+
 	/*
 	 * Do not complicate things with the async wake_list while the CPU is
 	 * in hotplug state.
@@ -4799,7 +4796,7 @@ int sched_fork(unsigned long clone_flags, struct task_struct *p)
 	} else if (rt_prio(p->prio)) {
 		p->sched_class = &rt_sched_class;
 #ifdef CONFIG_SCHED_CLASS_EXT
-	} else if (task_on_scx(p)) {
+	} else if (task_should_scx(p)) {
 		p->sched_class = &ext_sched_class;
 #endif
 	} else {
@@ -7096,7 +7093,7 @@ void __setscheduler_prio(struct task_struct *p, int prio)
 	else if (rt_prio(prio))
 		p->sched_class = &rt_sched_class;
 #ifdef CONFIG_SCHED_CLASS_EXT
-	else if (task_on_scx(p))
+	else if (task_should_scx(p))
 		p->sched_class = &ext_sched_class;
 #endif
 	else

kernel/sched/debug.c

@@ -1097,7 +1097,7 @@ void proc_sched_show_task(struct task_struct *p, struct pid_namespace *ns,
 		P(dl.deadline);
 	}
 #ifdef CONFIG_SCHED_CLASS_EXT
-	__PS("ext.enabled", p->sched_class == &ext_sched_class);
+	__PS("ext.enabled", task_on_scx(p));
 #endif
 #undef PN_SCHEDSTAT
 #undef P_SCHEDSTAT

kernel/sched/ext.c

@@ -2867,7 +2867,7 @@ static void scx_cgroup_config_knobs(void) {}
  * Used by sched_fork() and __setscheduler_prio() to pick the matching
  * sched_class. dl/rt are already handled.
  */
-bool task_on_scx(struct task_struct *p)
+bool task_should_scx(struct task_struct *p)
 {
 	if (!scx_enabled() || scx_ops_disabling())
 		return false;

kernel/sched/ext.h

@@ -110,7 +110,12 @@ DECLARE_STATIC_KEY_FALSE(__scx_switched_all);
 
 DECLARE_STATIC_KEY_FALSE(scx_ops_cpu_preempt);
 
-bool task_on_scx(struct task_struct *p);
+static inline bool task_on_scx(struct task_struct *p)
+{
+	return scx_enabled() && p->sched_class == &ext_sched_class;
+}
+
+bool task_should_scx(struct task_struct *p);
 void scx_pre_fork(struct task_struct *p);
 int scx_fork(struct task_struct *p);
 void scx_post_fork(struct task_struct *p);
@@ -198,6 +203,7 @@ bool scx_prio_less(const struct task_struct *a, const struct task_struct *b,
 #define scx_enabled()		false
 #define scx_switched_all()	false
 
+static inline bool task_on_scx(struct task_struct *p) { return false; }
 static inline void scx_pre_fork(struct task_struct *p) {}
 static inline int scx_fork(struct task_struct *p) { return 0; }
 static inline void scx_post_fork(struct task_struct *p) {}