Messages in this thread Patch in this message | | | Date | Tue, 24 Nov 2009 16:56:51 GMT | From | tip-bot for Tim Blechmann <> | Subject | [tip:sched/core] sched: Optimize branch hint in context_switch() |
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Commit-ID: 710390d90f143a9ebb87a475215140f426792efd Gitweb: http://git.kernel.org/tip/710390d90f143a9ebb87a475215140f426792efd Author: Tim Blechmann <tim@klingt.org> AuthorDate: Tue, 24 Nov 2009 11:55:27 +0100 Committer: Ingo Molnar <mingo@elte.hu> CommitDate: Tue, 24 Nov 2009 12:18:42 +0100
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 <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: <4B0BBB9F.6080304@klingt.org> Signed-off-by: Ingo Molnar <mingo@elte.hu> --- kernel/sched.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/sched.c b/kernel/sched.c index 93474a7..010d5e1 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -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; }
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