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SubjectRe: [patch 04/11] mutex subsystem, add include/asm-x86_64/mutex.h

* Eric Dumazet <dada1@cosmosbay.com> wrote:

> >+ :"=D" (dummy) \
> >+ : "D" (v) \
> >+ : "rax", "rsi", "rdx", "rcx", \
> >+ "r8", "r9", "r10", "r11", "memory"); \
> >+} while (0)
>
> Hi Ingo
>
> I do think this assembly is not very fair. It has an *insane* register
> pressure for the compiler : The fast path is thus not so fast.

if you look at the compiler output you'll notice that it's not a problem
actually: this fastpath is only inlined into the generic code, where it
has no clobbering side-effects.

you are right in that if this were to be inlined left and right, this
would be quite bad.

Ingo
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