sched/core: Skip rq lock in try_to_wake_up() when WALT is disabled

When WALT is disabled, do_pl_notif() always returns false, in which case
this bit of code serves no purpose. As a result, this WALT-specific code
spins on acquiring the rq lock in a hot path, wasting CPU time. Compile
it out when WALT is disabled to eliminate the unnecessary overhead.

Change-Id: I94ec3f2ce0faad049c0bf4974b2b4442883311a4
Signed-off-by: Sultan Alsawaf <sultan@kerneltoast.com>

kernel/sched/core.c

@@ -2205,6 +2205,7 @@ stat:
 out:
 	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
 
+#ifdef CONFIG_SCHED_WALT
 	if (success && sched_predl) {
 		raw_spin_lock_irqsave(&cpu_rq(cpu)->lock, flags);
 		if (do_pl_notif(cpu_rq(cpu)))
@@ -2213,6 +2214,7 @@ out:
 					    SCHED_CPUFREQ_PL);
 		raw_spin_unlock_irqrestore(&cpu_rq(cpu)->lock, flags);
 	}
+#endif
 	return success;
 }