Open MPI logo

Open MPI User's Mailing List Archives

  |   Home   |   Support   |   FAQ   |  

This web mail archive is frozen.

This page is part of a frozen web archive of this mailing list.

You can still navigate around this archive, but know that no new mails have been added to it since July of 2016.

Click here to be taken to the new web archives of this list; it includes all the mails that are in this frozen archive plus all new mails that have been sent to the list since it was migrated to the new archives.

Subject: [OMPI users] (no subject)
From: Julia He (springwater4he_at_[hidden])
Date: 2009-08-18 10:27:45


I found that the subroutine call inside a loop did not return correct value after certain iterations. In order to simplify the problem, the inputs to the subroutine are chosen to be constant, so the output should be the same for every iteration on every computing node. It is a fortran program, after the initialization the program goes like this:

do i = 1, N
  call my_sub(A, B, C, re)
  print *,  mypn, A, B, C, re
end do

where re is the output value of the my_sub, A, B, C are inputs to my_sub.

570 is the number of correct iterations. If the combined instances does not exceed 570, the output is fine. For example, if I requested 10 computing nodes and N were 40, so it gives 10*40=400 instances, the output would be fine. But if the combined instances exceeded 570, the first 570 is fine, but the rest will return NaN value. For example, if the number of computing nodes were 20 and N were 40, which gives 20*40=800 instances, then the first 570 are fine, but the rest are NaN value.

Does someone know what might cause the problem? I googled it, but can't find a clue where to start. Please also let me know what else you need to debug the problem.