[mpich-discuss] Semantics of asynchronous I/O operations in MPI3

[Rajeev Thakur]

The file pointers are updated in the order in which the functions are called. The functions don't have to complete in the order issued. For example, if you had called MPI_Waitany instead of Waitall, you can't say which iwrite will be indicated as completed when the waitany returns.

Rajeev

On Mar 8, 2013, at 8:04 AM, Matthieu Dorier wrote:

> Hi,
> 
> I can't manage to find a clear answer to this question in the MPI3 standard book;
> Assume we chain several asynchronous I/O operation on the same file, such as
> 
> MPI_File_iwrite(...)
> MPI_File_set_view(...)
> MPI_File_iwrite(...)
> MPI_File_iwrite(...)
> MPI_Wait_all(all requests from previous calls)
> 
> (equivalently with any other collective or independent asynchronous file accesses)
> Is an implementation of the MPI3 standard supposed to perform these operations in the same order than the functions are called, or can they be re-ordered if they are not in conflict (regions written are distinct)?
> 
> Thanks!
> 
> Matthieu Dorier
> PhD student at ENS Cachan Brittany and IRISA
> http://people.irisa.fr/Matthieu.Dorier
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