Re: [Starpu-devel] mpi_isend_detached / mpi_irecv_detached with starpu-trunk with tag

[Nathalie Furmento <nathalie.furmento@labri.fr>]

On 26/02/2015 10:08, Jean-Marie Couteyen wrote:
> Hello,
>
> it seems that tag are no longer taken into account for communication 
> when calling "starpu_mpi_isend_detached" / "starpu_mpi_irecv_detached" 
> with the trunk version.
> A magical value (_STARPU_MPI_TAG_DATA) replace the tag given when 
> StarPU calls Isend (_starpu_mpi_isend_data_func:327)
>
> I do rely on tags to make my communications on my application 
> (multiple isend_detached/irecv_detached identified by tags) and I 
> can't see a way to do them without it.
> Is there a good reason to override the given tag ?
>
> Regards,
> Jean-Marie Couteyen
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The communication engine in the trunk has been completely rewritten 
compared to the 1.1 version. We found out that implementations of MPI 
were not efficient when using too many different tags.

Thus the new engine sends all data using the same tag. However the tags 
given by the application should be matched properly. It might not be 
tested though by our testcases. I will have a look.

How long have you been using the trunk? I recently modified the engine 
to properly implement synchronous communications, it may have broken the 
tag matching system.

Cheers,

Nathalie