Messages in this thread Patch in this message |  | | Date | Tue, 24 Nov 2009 16:57:05 GMT | | From | tip-bot for Tim Blechmann <> | | Subject | [tip:sched/core] sched, x86: Optimize branch hint in __switch_to() |
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Commit-ID: a3a1de0c34de6f5f8332cd6151c46af7813c0fcb Gitweb: http://git.kernel.org/tip/a3a1de0c34de6f5f8332cd6151c46af7813c0fcb Author: Tim Blechmann <tim@klingt.org> AuthorDate: Tue, 24 Nov 2009 11:55:15 +0100 Committer: Ingo Molnar <mingo@elte.hu> CommitDate: Tue, 24 Nov 2009 12:20:04 +0100
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> --- arch/x86/kernel/process_64.c | 5 ++--- 1 files changed, 2 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index ad535b6..d9db104 100644 --- 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);
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