sched: do not do cond_resched() when CONFIG_PREEMPT

Why do we even have cond_resched when real preemption
is on? It seems to be a waste of space and time.

remove cond_resched with CONFIG_PREEMPT on.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 14 insertions, 3 deletions

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 94bc99656963..a7283c9beadf 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -105,8 +105,8 @@ struct user;
  * supposed to.
  */
 #ifdef CONFIG_PREEMPT_VOLUNTARY
-extern int cond_resched(void);
-# define might_resched() cond_resched()
+extern int _cond_resched(void);
+# define might_resched() _cond_resched()
 #else
 # define might_resched() do { } while (0)
 #endif
diff --git a/include/linux/sched.h b/include/linux/sched.h
index fe3f8fbc614e..7907845c2348 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1885,7 +1885,18 @@ static inline int need_resched(void)
  * cond_resched_lock() will drop the spinlock before scheduling,
  * cond_resched_softirq() will enable bhs before scheduling.
  */
-extern int cond_resched(void);
+#ifdef CONFIG_PREEMPT
+static inline int cond_resched(void)
+{
+        return 0;
+}
+#else
+extern int _cond_resched(void);
+static inline int cond_resched(void)
+{
+        return _cond_resched();
+}
+#endif
 extern int cond_resched_lock(spinlock_t * lock);
 extern int cond_resched_softirq(void);