RE: [PATCH] lockref: remove cpu_relax() again

[Luck, Tony]

> Also, it strikes me that ia64 has tons of different versions of
> cmpxchg, and the one you use by default is the one with "acquire"
> semantics

Not "tons", just two.  You can ask for "acquire" or "release" semantics,
there is no relaxed option.

Worse still - early processor implementations actually just ignored
the acquire/release and did a full fence all the time.  Unfortunately
this meant a lot of badly written code that used .acq when they really
wanted .rel became legacy out in the wild - so when we made a cpu
that strictly did the .acq or .rel ... all that code started breaking - so
we had to back-pedal and keep the "legacy" behavior of a full fence :-(

-Tony

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