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>

1 files changed, 5 insertions, 3 deletions

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;