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SubjectRe: [PATCH 13/15] x86: add cmpxchg_flag() variant
On Tue, 23 Aug 2011, Jeremy Fitzhardinge wrote:

> However, having prototyped it, I dunno, it doesn't really seem like much
> of a win for all the extra code it adds. I just can't get too excited
> about an extra test instruction adjacent to a monster like a locked
> cmpxchg. The jump variant avoids the test, but gcc still generates some
> pretty bogus stuff:

There are also unlocked cmpxchges in use. And if the cmpxchg is a 16 byte
cmpxchg (cmpxchg_double) then the comparison is getting more expensive.

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