[mpich-discuss] gather, send

Ryan Crocker rcrocker at uvm.edu
Wed May 1 18:55:19 CDT 2013


I just looked at the gsend_buffer, that's actually all zeros as well, and each send_buffer is not.  So i think my problem is there.

On May 1, 2013, at 4:47 PM, Rajeev Thakur wrote:

> The count passed to MPI_Scatter should be the local size, i.e., the amount that gets sent to each process. Looks like what is being passed is the global size.
> 
> On May 1, 2013, at 6:21 PM, Ryan Crocker wrote:
> 
>> Hi all, 
>> 
>> So i don't know what the issue with this code snippet is but i cannot get the scatter call to work.  When i print out the recieve_buffer it comes out as all zeros.   The counters without the underscore are the core domains, with the o, the global domains.
>> 
>>  rec_count  = (imaxo-imino+1)*(jmaxo-jmino+1)*(kmaxo-kmino+1) 
>>  send_count = (imax_-imin_+1)*(jmax_-jmin_+1)*(kmax_-kmin_+1) 
>> 
>>  call MPI_GATHER  (send_buffer, send_count, MPI_REAL, gsend_buffer, send_count, MPI_REAL, iroot, comm, ierr)
>> 
>>  rec_count  = (imaxo-imino+1)*(jmaxo-jmino+1)*(kmaxo-kmino+1) 
>>  send_count = (imaxo-imino+1)*(jmaxo-jmino+1)*(kmaxo-kmino+1) 
>> 
>>  call MPI_SCATTER (gsend_buffer, send_count, MPI_REAL, recieve_buffer, rec_count, MPI_REAL, iroot, comm, ierr)
>> 
>> thanks for the help.
>> 
>> Ryan Crocker
>> University of Vermont, School of Engineering
>> Mechanical Engineering Department
>> rcrocker at uvm.edu
>> 
>> 
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Ryan Crocker
University of Vermont, School of Engineering
Mechanical Engineering Department
rcrocker at uvm.edu
315-212-7331




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