sched: speed up update_load_add/_sub()

speed up update_load_add/_sub() by not delaying the division - this
reduces CPU pipeline dependencies.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/kernel/sched.c b/kernel/sched.c
index 3209e2c..992a1fa 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -697,16 +697,17 @@ calc_delta_fair(unsigned long delta_exec, struct load_weight *lw)
        return calc_delta_mine(delta_exec, NICE_0_LOAD, lw);
 }
 
-static void update_load_add(struct load_weight *lw, unsigned long inc)
+static inline void update_load_add(struct load_weight *lw, unsigned long inc)
 {
        lw->weight += inc;
-       lw->inv_weight = 0;
+       lw->inv_weight = WMULT_CONST / lw->weight;
 }
 
-static void update_load_sub(struct load_weight *lw, unsigned long dec)
+static inline void update_load_sub(struct load_weight *lw, unsigned long dec)
 {
        lw->weight -= dec;
-       lw->inv_weight = 0;
+       if (likely(lw->weight))
+               lw->inv_weight = WMULT_CONST / lw->weight;
 }
 
 /*