[cpp-threads] modes

[Peter Dimov]

Doug Lea wrote:

> One question is whether distinguishing CAS.none buys you anything vs
> CAS.rel wrt performance on current or plausible future platforms.
> Which I think is mainly another empirical question about PPC-smps. (I
> don't have one around to check either.)

I think that the answer here is almost certainly "yes" (maybe even with 
capital letters), because PPC CAS.rel is CAS.none prefixed with (lw)sync, 
and a sync (even the lightweight variation - which is not available 
everywhere) is expensive.

http://decadentplace.org.uk/pipermail/cpp-threads_decadentplace.org.uk/2005-March/000203.html