From: Mike Galbraith <efault@gmx.de>
Date: Mon, 12 May 2008 19:20:55 +0000 (+0200)
Subject: sched: make !hrtick faster
X-Git-Tag: firefly_0821_release~19700^2~75
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=f333fdc9098b71e2687e4e9b6349fcb352960d66;p=firefly-linux-kernel-4.4.55.git

sched: make !hrtick faster

it is safe to ignore timers and flags when the feature is disabled.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---

diff --git a/kernel/sched.c b/kernel/sched.c
index 7178b8c2351c..aa960b84b881 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4134,7 +4134,7 @@ asmlinkage void __sched schedule(void)
 	struct task_struct *prev, *next;
 	unsigned long *switch_count;
 	struct rq *rq;
-	int cpu;
+	int cpu, hrtick = sched_feat(HRTICK);
 
 need_resched:
 	preempt_disable();
@@ -4149,7 +4149,8 @@ need_resched_nonpreemptible:
 
 	schedule_debug(prev);
 
-	hrtick_clear(rq);
+	if (hrtick)
+		hrtick_clear(rq);
 
 	/*
 	 * Do the rq-clock update outside the rq lock:
@@ -4197,7 +4198,8 @@ need_resched_nonpreemptible:
 	} else
 		spin_unlock_irq(&rq->lock);
 
-	hrtick_set(rq);
+	if (hrtick)
+		hrtick_set(rq);
 
 	if (unlikely(reacquire_kernel_lock(current) < 0))
 		goto need_resched_nonpreemptible;