[MPI3 Fortran] [Interop-tr] [Mpi-forum] Comment on Fortran WG5 ballot N1846

[John Reid]

Rolf Rabenseifner wrote:
> John,
> 
> this is already handled by all hints about code movement and
> register optimization in the old MPI-2.2 and in more
> detail in the upcoming MPI-3.0.
> 
> To summarize, there are several options:
>  - TARGET buf
>  - Using a call to a dummy routine MPI_F_SYNC_REG(buf) 
>    immediately after MPI_Wait
>  - Storing buf as a module variable or in a common block
>  - (VOALTILE buf, not recommended)
> 
> 'ASYNCHRONOUS buf' is explicitly not an option, because
> a Fortran compiler 
> - that implements Fortran asynchronous input/output
>   with blocking I/O routines
> - is allowed to ignore the ASYNCHRONOUS attribute.
> 
> Only compilers with really asynchronous Fortran I/O
> have to also internally imply the TARGET attribute when 
> the ASYNCHRONOUS attribute is given in the application.
> 
> Is my analysis correct?

Yes, but they all seem clugey and error prone to me.

Given that asynchronous communication and asynchronous I/O are so alike and we 
already have syntax for the latter, should we not apply it also to the former? 
Even the word is appropriate.

Cheers,

John.


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