[OpenMP] SpeedUp for array initialization

Hi all,

I'm investigating a problem that I could boild down to basically the array initialization - which does not really seem to give me any speedup on Windows OS.

Consider the following piece of code:

integer, dimension(:), allocatable :: a
integer :: dim=8000000
integer i

allocate(a(1:dim))

!$OMP PARALLEL DO
do i=1,dim
   a(i)=0
enddo
!$OMP END PARALLEL DO

Then I do virtually get no speedup out of the parallel region.

Is this intended to be, or am I doing something stupid wrong ?



I was thinking that there are different NUMA-issues on Windows making the First-touch policy from Linux OS being "less valid" on Windows. However, I do observe the problem also when limiting myself to a single socket.