Fortran OpenACC issue for array of rank 5

Accelerated Computing HPC Compilers Legacy PGI Compilers
#1

Hello,

I encounter an issue with the PGI compiler and OpenACC when an array of 5 ranks is used in a computational region.
The issue is present from PGI 15.1 to 16.7.

Here is a reproducer.

program testcase_pgi 

implicit none

! --variable
integer, parameter :: SIZE=400
real, dimension(SIZE,SIZE,SIZE,4,4) :: velocity
integer :: i,j,k,ig,mx

!-- initialization
velocity=10.0
!


!--loop

do ig=1,4

print *,"ig", ig
!$ACC PARALLEL COPY(velocity(:,:,:,:,:))
!$ACC LOOP COLLAPSE(3)
  do k=1,SIZE
   do j=1,SIZE
     do i=1,SIZE

    velocity(i,j,k,ig,ig) = velocity(i,j,k,ig,ig) + 10.0

  enddo
   enddo
     enddo
  !$ACC END PARALLEL
                enddo


end program testcase_pgi




call to cuMemFreeHost returned error 700: Illegal address during kernel execution

Any ideas ?

Thank you

#2

Hi MHUGHES,

When I run your code, I get the same error for both 15.1 and 16.7. The problem being that your static array is greater than 2GB which requires the medium memory model. Hence the fix is to compile with “-mcmodel=medium”.

% pgfortran -acc test_10_17_16.f90 -V16.7
% a.out
 ig            1
 ig            2
 ig            3
call to cuStreamSynchronize returned error 700: Illegal address during kernel execution
call to cuMemFreeHost returned error 700: Illegal address during kernel execution
% pgfortran -acc test_10_17_16.f90 -V16.7 -mcmodel=medium
% a.out
 ig            1
 ig            2
 ig            3
 ig            4

Hope this helps,
Mat

#3

Hello Mat,

Thank you very much for your help.
This is fixing the issue. I did not think about the array being bigger than 2GB.

Max

#4

Hello Mat,

I realized that we are using a dynamic array instead of a static array.
the use of -mcmodel=medium fixes the problem. It is weird to have this issue on dynamic array.