sched/core: Introduce sched_asym_cpucap_active()

Create an inline helper for conditional code to be only executed on
asymmetric CPU capacity systems. This makes these (currently ~10 and
future) conditions a lot more readable.
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20220729111305.1275158-2-dietmar.eggemann@arm.com

kernel/sched/cpudeadline.c

@@ -123,7 +123,7 @@ int cpudl_find(struct cpudl *cp, struct task_struct *p,
 		unsigned long cap, max_cap = 0;
 		int cpu, max_cpu = -1;
 
-		if (!static_branch_unlikely(&sched_asym_cpucapacity))
+		if (!sched_asym_cpucap_active())
 			return 1;
 
 		/* Ensure the capacity of the CPUs fits the task. */

kernel/sched/deadline.c

@@ -144,7 +144,7 @@ static inline unsigned long __dl_bw_capacity(int i)
  */
 static inline unsigned long dl_bw_capacity(int i)
 {
-	if (!static_branch_unlikely(&sched_asym_cpucapacity) &&
+	if (!sched_asym_cpucap_active() &&
 	    capacity_orig_of(i) == SCHED_CAPACITY_SCALE) {
 		return dl_bw_cpus(i) << SCHED_CAPACITY_SHIFT;
 	} else {
@@ -1849,7 +1849,7 @@ select_task_rq_dl(struct task_struct *p, int cpu, int flags)
 	 * Take the capacity of the CPU into account to
 	 * ensure it fits the requirement of the task.
 	 */
-	if (static_branch_unlikely(&sched_asym_cpucapacity))
+	if (sched_asym_cpucap_active())
 		select_rq |= !dl_task_fits_capacity(p, cpu);
 
 	if (select_rq) {

kernel/sched/fair.c

@@ -4262,7 +4262,7 @@ static inline int task_fits_capacity(struct task_struct *p,
 
 static inline void update_misfit_status(struct task_struct *p, struct rq *rq)
 {
-	if (!static_branch_unlikely(&sched_asym_cpucapacity))
+	if (!sched_asym_cpucap_active())
 		return;
 
 	if (!p || p->nr_cpus_allowed == 1) {
@@ -6506,7 +6506,7 @@ select_idle_capacity(struct task_struct *p, struct sched_domain *sd, int target)
 
 static inline bool asym_fits_capacity(unsigned long task_util, int cpu)
 {
-	if (static_branch_unlikely(&sched_asym_cpucapacity))
+	if (sched_asym_cpucap_active())
 		return fits_capacity(task_util, capacity_of(cpu));
 
 	return true;
@@ -6526,7 +6526,7 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target)
 	 * On asymmetric system, update task utilization because we will check
 	 * that the task fits with cpu's capacity.
 	 */
-	if (static_branch_unlikely(&sched_asym_cpucapacity)) {
+	if (sched_asym_cpucap_active()) {
 		sync_entity_load_avg(&p->se);
 		task_util = uclamp_task_util(p);
 	}
@@ -6580,7 +6580,7 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target)
 	 * For asymmetric CPU capacity systems, our domain of interest is
 	 * sd_asym_cpucapacity rather than sd_llc.
 	 */
-	if (static_branch_unlikely(&sched_asym_cpucapacity)) {
+	if (sched_asym_cpucap_active()) {
 		sd = rcu_dereference(per_cpu(sd_asym_cpucapacity, target));
 		/*
 		 * On an asymmetric CPU capacity system where an exclusive

kernel/sched/rt.c

@@ -509,7 +509,7 @@ static inline bool rt_task_fits_capacity(struct task_struct *p, int cpu)
 	unsigned int cpu_cap;
 
 	/* Only heterogeneous systems can benefit from this check */
-	if (!static_branch_unlikely(&sched_asym_cpucapacity))
+	if (!sched_asym_cpucap_active())
 		return true;
 
 	min_cap = uclamp_eff_value(p, UCLAMP_MIN);
@@ -1897,7 +1897,7 @@ static int find_lowest_rq(struct task_struct *task)
 	 * If we're on asym system ensure we consider the different capacities
 	 * of the CPUs when searching for the lowest_mask.
 	 */
-	if (static_branch_unlikely(&sched_asym_cpucapacity)) {
+	if (sched_asym_cpucap_active()) {
 
 		ret = cpupri_find_fitness(&task_rq(task)->rd->cpupri,
 					  task, lowest_mask,

kernel/sched/sched.h

@@ -1813,6 +1813,11 @@ DECLARE_PER_CPU(struct sched_domain __rcu *, sd_asym_packing);
 DECLARE_PER_CPU(struct sched_domain __rcu *, sd_asym_cpucapacity);
 extern struct static_key_false sched_asym_cpucapacity;
 
+static __always_inline bool sched_asym_cpucap_active(void)
+{
+	return static_branch_unlikely(&sched_asym_cpucapacity);
+}
+
 struct sched_group_capacity {
 	atomic_t		ref;
 	/*