sched: Optimize branch hint in context_switch()

Branch hint profiling on my nehalem machine showed over 90%
incorrect branch hints:

  10420275 170645395  94 context_switch                 sched.c
   3043
  10408421 171098521  94 context_switch                 sched.c
   3050

Signed-off-by: Tim Blechmann <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
This commit is contained in:
Tim Blechmann 2009-11-24 11:55:27 +01:00 • committed by Ingo Molnar
commit 710390d90f

View file

@ -2829,14 +2829,14 @@ context_switch(struct rq *rq, struct task_struct *prev,
*/
arch_start_context_switch(prev);
if (unlikely(!mm)) {
if (likely(!mm)) {
next->active_mm = oldmm;
atomic_inc(&oldmm->mm_count);
enter_lazy_tlb(oldmm, next);
} else
switch_mm(oldmm, mm, next);
if (unlikely(!prev->mm)) {
if (likely(!prev->mm)) {
prev->active_mm = NULL;
rq->prev_mm = oldmm;
}