Messages in this thread | | | Date | Mon, 1 Jul 2013 16:36:47 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH] x86: Use asm-goto to implement mutex fast path on x86-64 |
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On Mon, Jul 01, 2013 at 07:30:14AM -0700, H. Peter Anvin wrote: > Unconditional branches don't need prediction. The branch predictor > is used for conditional branches and in some hardware designs for > indirect branches. Unconditional direct branches never go through > the branch predictor simply because the front end can know with 100% > certainty where the flow of control will be.
I meant the conditional Jcc branches:
ffffffff81774920 <mutex_lock>:
...
ffffffff8177492d: f0 ff 0b lock decl (%rbx) ffffffff81774930: 79 08 jns ffffffff8177493a <mutex_lock+0x1a>
ffffffff81774730 <mutex_unlock>:
...
ffffffff81774738: f0 ff 07 lock incl (%rdi) ffffffff8177473b: 7f 0a jg ffffffff81774747 <mutex_unlock+0x17>
-- Regards/Gruss, Boris.
Sent from a fat crate under my desk. Formatting is fine. --
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