sched: remove extra call overhead for schedule()

Lai Jiangshan's patch reminded me that I promised Nick to remove
that extra call overhead in schedule().

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20090313112300.927414207@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/mutex.c b/kernel/mutex.c
index 5d79781..e1fb735 100644 (file)
--- a/kernel/mutex.c
+++ b/kernel/mutex.c
@@ -248,7 +248,9 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
 
                /* didnt get the lock, go to sleep: */
                spin_unlock_mutex(&lock->wait_lock, flags);
-               __schedule();
+               preempt_enable_no_resched();
+               schedule();
+               preempt_disable();
                spin_lock_mutex(&lock->wait_lock, flags);
        }
 

diff --git a/kernel/sched.c b/kernel/sched.c
index 7601cee..797f6fd 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -5131,13 +5131,15 @@ pick_next_task(struct rq *rq)
 /*
  * schedule() is the main scheduler function.
  */
-asmlinkage void __sched __schedule(void)
+asmlinkage void __sched schedule(void)
 {
        struct task_struct *prev, *next;
        unsigned long *switch_count;
        struct rq *rq;
        int cpu;
 
+need_resched:
+       preempt_disable();
        cpu = smp_processor_id();
        rq = cpu_rq(cpu);
        rcu_qsctr_inc(cpu);
@@ -5194,15 +5196,9 @@ need_resched_nonpreemptible:
 
        if (unlikely(reacquire_kernel_lock(current) < 0))
                goto need_resched_nonpreemptible;
-}
 
-asmlinkage void __sched schedule(void)
-{
-need_resched:
-       preempt_disable();
-       __schedule();
        preempt_enable_no_resched();
-       if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
+       if (need_resched())
                goto need_resched;
 }
 EXPORT_SYMBOL(schedule);