Re: [boost] [interprocess] Atomic ops supports for Alpha processors.

From: Markus Schöpflin (markus.schoepflin_at_[hidden])
Date: 2007-11-09 06:52:31

Peter Dimov wrote:

> Markus Schöpflin:
> 
>> Peter,
>>
>> I have read your paper referenced above and a few of the other papers
>> dealing with atomic ops, but I failed to find a clear definition of what
>> 'acquire' and 'release' semantics are supposed to mean. Could you point
>> me into the right direction, please? Also, in your paper you're
>> referring to [intro.concur], where could I find this?
> 
> I think that the relevant paper at the moment is
> 
> http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2334.htm
> 
> Basically, if a thread A load-acquires a memory location that has been 
> store-released by thread B, then after the load thread A is guaranteed to 
> see the updates that thread B has done prior to the store. 

Peter, I have been reading your paper again and I'm puzzled by the 
following sentence (section 'Fences'): "Release, ensures that all preceding 
operations in program order are performed after all subsequent stores in 
program order;".

Shouldn't that read that all preceding operations are performed _before_ 
all subsequent stores, instead of after?

Markus