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authorHeiko Carstens <heiko.carstens@de.ibm.com>2010-09-16 14:42:25 +0200
committerIngo Molnar <mingo@elte.hu>2010-09-16 16:38:34 +0200
commit31915ab4cbf507aadab40847cf9989da5e88b090 (patch)
tree48f7f64cbfd82ee88cece1384e6eb949ef2cbed0 /kernel/sched.c
parent7740191cd909b75d75685fb08a5d1f54b8a9d28b (diff)
sched: Remove branch hints within context_switch()
With 710390d9 "sched: Optimize branch hint in context_switch()" the branch hint logic within context_switch() got inversed. In fact the hints "if (likely(!mm))" and "if (likely(!prev->mm))" mean that it is likely that the previous and next task are kernel threads. That assumption is certainly counter intuitive, but Tim has shown that at least with his workload this is true. Nevertheless the truth is: it depends on the current workload. So just remove the annotations which also improves readability. Reported-by: Tim Blechmann <tim@klingt.org> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Mike Galbraith <efault@gmx.de> LKML-Reference: <20100916124225.GA2209@osiris.boeblingen.de.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/sched.c')
-rw-r--r--kernel/sched.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index b40b82e3359..16a1129f51e 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2845,14 +2845,14 @@ context_switch(struct rq *rq, struct task_struct *prev,
*/
arch_start_context_switch(prev);
- if (likely(!mm)) {
+ if (!mm) {
next->active_mm = oldmm;
atomic_inc(&oldmm->mm_count);
enter_lazy_tlb(oldmm, next);
} else
switch_mm(oldmm, mm, next);
- if (likely(!prev->mm)) {
+ if (!prev->mm) {
prev->active_mm = NULL;
rq->prev_mm = oldmm;
}