Re: Synchronizing Bit operations V2

[Andi Kleen]

On Friday 31 March 2006 18:22, Hans Boehm wrote:

> My impression is that approach (1) tends not to stick, since it involves
> a substantial performance hit on architectures on which the fence is
> not implicitly included in atomic operations.  Those include Itanium and
> PowerPC.

At least the PPC people are eating the overhead because back when they
didn't they had a long string of subtle powerpc only bugs caused by that

It's a stability/maintainability vs performance issue. I doubt the 
performance advantage would be worth the additional work. I guess
with the engineering time you would need to spend getting all this right
you could do much more fruitful optimizations.

-Andi
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