[Mpi-forum] MPI_Type_create_struct vs. other datatype creation routines

Pavan Balaji balaji at mcs.anl.gov
Mon Aug 29 20:29:43 CDT 2011

On 08/29/2011 01:52 PM, Mohamad Chaarawi wrote:
> On 08/29/2011 09:21 AM, Pavan Balaji wrote:
>> Great. We have a use case for this as well, and we are essentially
>> doing exactly what you are doing. Are you planning to do a formal
>> reading for it at the next meeting?
> We would like to, but unfortunately none from the HDF group are able to
> attend the forum meeting in September. If you, or anyone  to that
> matter, would like to do a formal reading for this ticket, please let me
> know. Otherwise it will have to wait for the Chicago meeting in October.

I'm not going, but it'll be good if someone at least presents this to 
the Forum in September. I'm sure we can find a volunteer.

>> Btw, hindexed is not a real replacement for indexed as the MPI
>> implementation can be better optimized for indexed than hindexed
>> (e.g., alignment checks). So the right solution would have been to
>> allow indexed to take MPI_Aint arguments as well. But given that the
>> performance difference would be so small, I'm not sure if we should
>> create yet another set of routines for it.
> I'm not really sure what you mean. How can we specify a displacement in
> multiples of old type and byte displacements in the same function? I
> thought it has to be one or the other.

Not in the same function. New functions, of course. For byte 
displacements, nothing needs to change. For the displacement with 
respect to multiples of old type, we need something better.

  -- Pavan

Pavan Balaji

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