(j3.2006) (SC22WG5.3717) [ukfortran] Atomic stuff

Bill Long longb
Wed Dec 3 15:23:19 EST 2008



Jim Xia wrote:
>
>
>
> Atomic loads and stores on mis-aligned variables are nearly impossible 
> on many hardwares (The solution to fix up the mis-alignment by either 
> hardware or OS causes the operation become non-atomic, let along the 
> performance hit).
>
> Three places I think will likely cause this mis-alignment: 
> EQUIVELENCE, COMMON BLOCK and structure component level.  The one that 
> is relevant to coarrays is structure component.  The other two will 
> apply to local objects only.  We need to think how to fix that.
>
I agree that the place where this issue is relevant is components of a 
coarray structure.   But certainly an implementation is not going to 
mis-align structure components in this way.   The performance hit would 
be horrible. 

Cheers,
Bill




-- 
Bill Long                                   longb at cray.com
Fortran Technical Support    &              voice: 651-605-9024
Bioinformatics Software Development         fax:   651-605-9142
Cray Inc., 1340 Mendota Heights Rd., Mendota Heights, MN, 55120

            




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