sched/topology: Consolidate and clean up access to a CPU's max compute capacity

Remove the rq::cpu_capacity_orig field and use arch_scale_cpu_capacity()
instead.

The scheduler uses 3 methods to get access to a CPU's max compute capacity:

 - arch_scale_cpu_capacity(cpu) which is the default way to get a CPU's capacity.

 - cpu_capacity_orig field which is periodically updated with
   arch_scale_cpu_capacity().

 - capacity_orig_of(cpu) which encapsulates rq->cpu_capacity_orig.

There is no real need to save the value returned by arch_scale_cpu_capacity()
in struct rq. arch_scale_cpu_capacity() returns:

 - either a per_cpu variable.

 - or a const value for systems which have only one capacity.

Remove rq::cpu_capacity_orig and use arch_scale_cpu_capacity() everywhere.

No functional changes.

Some performance tests on Arm64:

  - small SMP device (hikey): no noticeable changes
  - HMP device (RB5):         hackbench shows minor improvement (1-2%)
  - large smp (thx2):         hackbench and tbench shows minor improvement (1%)

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lore.kernel.org/r/20231009103621.374412-2-vincent.guittot@linaro.org

1 files changed, 2 insertions, 2 deletions

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index d98408a274e5..7039a8d5ae9b 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -132,7 +132,7 @@ static inline unsigned long __dl_bw_capacity(const struct cpumask *mask)
 	int i;
 
 	for_each_cpu_and(i, mask, cpu_active_mask)
-		cap += capacity_orig_of(i);
+		cap += arch_scale_cpu_capacity(i);
 
 	return cap;
 }
@@ -144,7 +144,7 @@ static inline unsigned long __dl_bw_capacity(const struct cpumask *mask)
 static inline unsigned long dl_bw_capacity(int i)
 {
 	if (!sched_asym_cpucap_active() &&
-	    capacity_orig_of(i) == SCHED_CAPACITY_SCALE) {
+	    arch_scale_cpu_capacity(i) == SCHED_CAPACITY_SCALE) {
 		return dl_bw_cpus(i) << SCHED_CAPACITY_SHIFT;
 	} else {
 		RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),