sched: Compute cpu capacity available at current frequency

capacity_orig_of() returns the max available compute capacity of a cpu.
For scale-invariant utilization tracking and energy-aware scheduling
decisions it is useful to know the compute capacity available at the
current OPP of a cpu.

cc: Ingo Molnar <mingo@redhat.com>
cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 3fa6b311f93a23d5db34a52027bf31e111320d6e..0650d998d30fb767ce67e2612084d391bef05fea 100644 (file)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4672,6 +4672,17 @@ static long effective_load(struct task_group *tg, int cpu, long wl, long wg)
 
 #endif
 
+/*
+ * Returns the current capacity of cpu after applying both
+ * cpu and freq scaling.
+ */
+static unsigned long capacity_curr_of(int cpu)
+{
+       return cpu_rq(cpu)->cpu_capacity_orig *
+              arch_scale_freq_capacity(NULL, cpu)
+              >> SCHED_CAPACITY_SHIFT;
+}
+
 static inline bool energy_aware(void)
 {
        return sched_feat(ENERGY_AWARE);