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>
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1 changed files with 2 additions and 2 deletions
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@ -2829,14 +2829,14 @@ context_switch(struct rq *rq, struct task_struct *prev,
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*/
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*/
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arch_start_context_switch(prev);
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arch_start_context_switch(prev);
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if (unlikely(!mm)) {
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if (likely(!mm)) {
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next->active_mm = oldmm;
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next->active_mm = oldmm;
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atomic_inc(&oldmm->mm_count);
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atomic_inc(&oldmm->mm_count);
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enter_lazy_tlb(oldmm, next);
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enter_lazy_tlb(oldmm, next);
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} else
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} else
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switch_mm(oldmm, mm, next);
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switch_mm(oldmm, mm, next);
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if (unlikely(!prev->mm)) {
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if (likely(!prev->mm)) {
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prev->active_mm = NULL;
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prev->active_mm = NULL;
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rq->prev_mm = oldmm;
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rq->prev_mm = oldmm;
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}
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}
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