[mpiwg-rma] Fwd: Use of MPI_SHORT_INT, etc with MPI_Accumulate

Jeff Hammond jeff.science at gmail.com
Wed May 11 09:37:39 CDT 2016



> From: Jeff Hammond <jeff.science at gmail.com>
> Date: May 11, 2016 at 5:34:12 PM GMT+3
> To: MPI WG Remote Memory Access working group <mpiwg-rma at mpi-forum.org>
> Cc: mpiwg-rma at lists.mpi-forum.org
> Subject: Re: [mpiwg-rma] Use of MPI_SHORT_INT, etc with MPI_Accumulate
> 
> How else can you call with eg op=MAXLOC?
> 
> Sent from my iPhone
> 
>> On May 11, 2016, at 5:02 PM, Nathan Hjelm <hjelmn at mac.com> wrote:
>> 
>> I have a user who is trying to use MPI_SHORT_INT as the origin and target datatype arguments of MPI_Accumulate. My interpretation of the standard does not allow this type. I am justifying this because of MPI 3-1 § 11.3.4 pp 425:2-8:
>> 
>> Each datatype argument must be a predefined datatype or a derived datatype, where
>> all basic components are of the same predefined datatype. Both datatype arguments must
>> be constructed from the same predefined datatype.
>> 
>> MPI_SHORT_INT, MPI_LONG_DOUBLE_INT, etc are not in any of the A.1 tables labeled as "predefined datatypes”. They show up in a separate list of datatypes for reduction functions. Since these datatypes are not “predefined datatypes” and are not composite datatypes of the "same predefined datatype” they are not valid for MPI_Accumulate, MPI_Get_accumulate, etc. Am I wrong in my interpretation?
>> 
>> -Nathan
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