sched/fair: Avoid an unnecessary lookup of current CPU ID during wake_affine

The only caller of wake_affine() knows the CPU ID. Pass it in instead of
rechecking it.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Giovanni Gherdovich <ggherdovich@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180213133730.24064-2-mgorman@techsingularity.netSigned-off-by: Ingo Molnar <mingo@kernel.org>

kernel/sched/fair.c

@@ -5751,9 +5751,8 @@ wake_affine_weight(struct sched_domain *sd, struct task_struct *p,
 }
 
 static int wake_affine(struct sched_domain *sd, struct task_struct *p,
-		       int prev_cpu, int sync)
+		       int this_cpu, int prev_cpu, int sync)
 {
-	int this_cpu = smp_processor_id();
 	int target = nr_cpumask_bits;
 
 	if (sched_feat(WA_IDLE))
@@ -6376,7 +6375,7 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f
 		if (cpu == prev_cpu)
 			goto pick_cpu;
 
-		new_cpu = wake_affine(affine_sd, p, prev_cpu, sync);
+		new_cpu = wake_affine(affine_sd, p, cpu, prev_cpu, sync);
 	}
 
 	if (sd && !(sd_flag & SD_BALANCE_FORK)) {