openmp 3.0 collapse

fah10 — Fri, 10 Jul 2009 21:59:12 GMT

Hi,

I have a problem concerning the collapse feature of OpenMP 3.0.
When the iteration count of the outer loop gets one as in the following example,
no parallel speed-up is achievable.

[cpp]program test
   integer, parameter :: n=100000000
   integer :: i,j,k
   real(kind=8), dimension(n) :: d

   k = n+1
   k = k-n
   ! k is now one
   print*,k

!$omp parallel do collapse(2)
   do i=1,k
      do j=1,n
         d(j) = sqrt(abs(sin(cos(tan(real(j*i,kind=8))))))
      end do
   end do
!$omp end parallel do

   print*,d(1)

end program test


The problem occurs with Intel Fortran 11.0
IBM and GNU Fortran do not seem to have this problem.
Am I doing something wrong, or is this a bug?

Cheers,
F. Ahaba

[/cpp]

topic openmp 3.0 collapse in Intel® Moderncode for Parallel Architectures

openmp 3.0 collapse