sched, x86: Optimize branch hint in __switch_to()

Branch hint profiling on my nehalem machine showed 96%
incorrect branch hints:

  6548732 174664120  96 __switch_to                    process_64.c
    406
  6548745 174565593  96 __switch_to                    process_64.c
    410

Signed-off-by: Tim Blechmann <tim@klingt.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4B0BBB93.3080307@klingt.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index ad535b6831700bfdac237942d22f4380dbb43417..d9db1049e86fc91b6b100d33ff8c6ae3586592c4 100644 (file)
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -406,11 +406,10 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
         * This won't pick up thread selector changes, but I guess that is ok.
         */
        savesegment(es, prev->es);
-       if (unlikely(next->es | prev->es))
+       if (next->es | prev->es)
                loadsegment(es, next->es);
-
        savesegment(ds, prev->ds);
-       if (unlikely(next->ds | prev->ds))
+       if (next->ds | prev->ds)
                loadsegment(ds, next->ds);