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Groups > linux.kernel > #1609233
| From | Peter Zijlstra <peterz@infradead.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: locking/atomic: Introduce atomic_try_cmpxchg() |
| Date | 2017-03-25 22:20 +0100 |
| Message-ID | <tp1gm-6A9-3@gated-at.bofh.it> (permalink) |
| References | (5 earlier) <toOMa-67F-15@gated-at.bofh.it> <toYit-4wW-1@gated-at.bofh.it> <toYBQ-4DA-17@gated-at.bofh.it> <toYLv-4H9-3@gated-at.bofh.it> <toYLv-4H9-1@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Sat, Mar 25, 2017 at 11:34:32AM -0700, Linus Torvalds wrote: > On Sat, Mar 25, 2017 at 11:28 AM, Linus Torvalds > <torvalds@linux-foundation.org> wrote: > > > > Hmm. Sad. The label approach looked like it would match the semantics > > of cmpxchg perfectly, but it's not as optimal as it superficially > > would have seemed. > > Oh, I just noticed that at least your other one didn't mark "success" > as being likely. 10730509 4540256 843776 16114541 f5e36d defconfig-build/vmlinux --- arch/x86/include/asm/cmpxchg.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/cmpxchg.h b/arch/x86/include/asm/cmpxchg.h index fb961db..d347abc 100644 --- a/arch/x86/include/asm/cmpxchg.h +++ b/arch/x86/include/asm/cmpxchg.h @@ -212,8 +212,9 @@ extern void __add_wrong_size(void) default: \ __cmpxchg_wrong_size(); \ } \ + if (unlikely(!success)) \ *_old = __old; \ - success; \ + likely(success); \ }) #define __try_cmpxchg(ptr, pold, new, size) \
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re: locking/atomic: Introduce atomic_try_cmpxchg() Dmitry Vyukov <dvyukov@google.com> - 2017-03-24 13:50 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Dmitry Vyukov <dvyukov@google.com> - 2017-03-24 15:30 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Peter Zijlstra <peterz@infradead.org> - 2017-03-24 15:30 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Peter Zijlstra <peterz@infradead.org> - 2017-03-24 17:50 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Andy Lutomirski <luto@amacapital.net> - 2017-03-24 18:00 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Peter Zijlstra <peterz@infradead.org> - 2017-03-24 18:30 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Dmitry Vyukov <dvyukov@google.com> - 2017-03-24 19:00 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Peter Zijlstra <peterz@infradead.org> - 2017-03-24 19:20 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Peter Zijlstra <peterz@infradead.org> - 2017-03-24 19:20 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Andy Lutomirski <luto@kernel.org> - 2017-03-24 20:20 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Linus Torvalds <torvalds@linux-foundation.org> - 2017-03-24 20:30 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Andy Lutomirski <luto@amacapital.net> - 2017-03-24 20:30 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Peter Zijlstra <peterz@infradead.org> - 2017-03-24 21:20 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Peter Zijlstra <peterz@infradead.org> - 2017-03-24 21:20 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Andy Lutomirski <luto@amacapital.net> - 2017-03-24 21:30 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Dmitry Vyukov <dvyukov@google.com> - 2017-03-24 19:20 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Peter Zijlstra <peterz@infradead.org> - 2017-03-24 19:10 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Peter Zijlstra <peterz@infradead.org> - 2017-03-24 19:20 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Andy Lutomirski <luto@amacapital.net> - 2017-03-24 19:50 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Linus Torvalds <torvalds@linux-foundation.org> - 2017-03-24 20:20 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Peter Zijlstra <peterz@infradead.org> - 2017-03-24 22:30 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Peter Zijlstra <peterz@infradead.org> - 2017-03-25 09:00 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Linus Torvalds <torvalds@linux-foundation.org> - 2017-03-25 19:10 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Peter Zijlstra <peterz@infradead.org> - 2017-03-25 19:30 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Linus Torvalds <torvalds@linux-foundation.org> - 2017-03-25 19:40 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Peter Zijlstra <peterz@infradead.org> - 2017-03-25 22:20 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Linus Torvalds <torvalds@linux-foundation.org> - 2017-03-25 23:10 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Peter Zijlstra <peterz@infradead.org> - 2017-03-27 12:00 +0200
Re: locking/atomic: Introduce atomic_try_cmpxchg() Linus Torvalds <torvalds@linux-foundation.org> - 2017-03-25 19:40 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Peter Zijlstra <peterz@infradead.org> - 2017-03-24 21:30 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Andy Lutomirski <luto@kernel.org> - 2017-03-24 21:30 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Peter Zijlstra <peterz@infradead.org> - 2017-03-24 22:10 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Linus Torvalds <torvalds@linux-foundation.org> - 2017-03-24 20:10 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Peter Zijlstra <peterz@infradead.org> - 2017-03-24 21:50 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Linus Torvalds <torvalds@linux-foundation.org> - 2017-03-24 22:00 +0100
Re: locking/atomic: Introduce atomic_try_cmpxchg() Peter Zijlstra <peterz@infradead.org> - 2017-03-27 14:20 +0200
Re: locking/atomic: Introduce atomic_try_cmpxchg() Dmitry Vyukov <dvyukov@google.com> - 2017-03-27 15:50 +0200
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