sched/fair: Convert arch_scale_cpu_capacity() from weak function to #define

Bring arch_scale_cpu_capacity() in line with the recent change of its
arch_scale_freq_capacity() sibling in commit dfbca41f3479 ("sched:
Optimize freq invariant accounting") from weak function to #define to
allow inlining of the function.

While at it, remove the ARCH_CAPACITY sched_feature as well. With the
change to #define there isn't a straightforward way to allow runtime
switch between an arch implementation and the default implementation of
arch_scale_cpu_capacity() using sched_feature. The default was to use
the arch-specific implementation, but only the arm architecture provides
one and that is essentially equivalent to the default implementation.

Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dietmar Eggemann <Dietmar.Eggemann@arm.com>
Cc: Juri Lelli <Juri.Lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: daniel.lezcano@linaro.org
Cc: mturquette@baylibre.com
Cc: pang.xunlei@zte.com.cn
Cc: rjw@rjwysocki.net
Cc: sgurrappadi@nvidia.com
Cc: vincent.guittot@linaro.org
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1439569394-11974-3-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/sched/fair.c

@@ -6054,19 +6054,6 @@ static inline int get_sd_load_idx(struct sched_domain *sd,
 	return load_idx;
 }
 
-static unsigned long default_scale_cpu_capacity(struct sched_domain *sd, int cpu)
-{
-	if ((sd->flags & SD_SHARE_CPUCAPACITY) && (sd->span_weight > 1))
-		return sd->smt_gain / sd->span_weight;
-
-	return SCHED_CAPACITY_SCALE;
-}
-
-unsigned long __weak arch_scale_cpu_capacity(struct sched_domain *sd, int cpu)
-{
-	return default_scale_cpu_capacity(sd, cpu);
-}
-
 static unsigned long scale_rt_capacity(int cpu)
 {
 	struct rq *rq = cpu_rq(cpu);
@@ -6096,16 +6083,9 @@ static unsigned long scale_rt_capacity(int cpu)
 
 static void update_cpu_capacity(struct sched_domain *sd, int cpu)
 {
-	unsigned long capacity = SCHED_CAPACITY_SCALE;
+	unsigned long capacity = arch_scale_cpu_capacity(sd, cpu);
 	struct sched_group *sdg = sd->groups;
 
-	if (sched_feat(ARCH_CAPACITY))
-		capacity *= arch_scale_cpu_capacity(sd, cpu);
-	else
-		capacity *= default_scale_cpu_capacity(sd, cpu);
-
-	capacity >>= SCHED_CAPACITY_SHIFT;
-
 	cpu_rq(cpu)->cpu_capacity_orig = capacity;
 
 	capacity *= scale_rt_capacity(cpu);

kernel/sched/features.h

@@ -36,11 +36,6 @@ SCHED_FEAT(CACHE_HOT_BUDDY, true)
  */
 SCHED_FEAT(WAKEUP_PREEMPTION, true)
 
-/*
- * Use arch dependent cpu capacity functions
- */
-SCHED_FEAT(ARCH_CAPACITY, true)
-
 SCHED_FEAT(HRTICK, false)
 SCHED_FEAT(DOUBLE_TICK, false)
 SCHED_FEAT(LB_BIAS, true)

kernel/sched/sched.h

@@ -1394,6 +1394,17 @@ unsigned long arch_scale_freq_capacity(struct sched_domain *sd, int cpu)
 }
 #endif
 
+#ifndef arch_scale_cpu_capacity
+static __always_inline
+unsigned long arch_scale_cpu_capacity(struct sched_domain *sd, int cpu)
+{
+	if ((sd->flags & SD_SHARE_CPUCAPACITY) && (sd->span_weight > 1))
+		return sd->smt_gain / sd->span_weight;
+
+	return SCHED_CAPACITY_SCALE;
+}
+#endif
+
 static inline void sched_rt_avg_update(struct rq *rq, u64 rt_delta)
 {
 	rq->rt_avg += rt_delta * arch_scale_freq_capacity(NULL, cpu_of(rq));