Hi Joe, I found the article you wrote for Linux Journal right about the time you emailed last night - thanks for the reference and the suggestions! I find that 1 beer and coding is ok, but num_beer .ge. 2 makes me too poetic and insufficiently detail oriented. Debugging the next morning is never fun.
On Fri, Nov 21, 2008 at 9:23 AM, Joe Landman < [EMAIL PROTECTED]> wrote: > Geoff Jacobs wrote: > > If this were done with MPI, one would have to be careful of the >> boundaries on the matrix as it's partitioned for computation. OpenMP is >> intelligent enough to hold off computation on the tiles south and east >> of the first until the first is done, and so forth? >> > > No... I didn't address the interior vs exterior. I have a nice worked > example where I convert this sort of code into an exterior, a skin, and the > communication for an MPI and OpenMP version. Scales pretty well. You are > right, I should have fixed that as well. > > >> ! now all you need is a "linear scan" to find positive elements in >>> ! dv. You can approach these as sum reductions, and do them in >>> ! parallel >>> do i=1,Nx >>> sum=0.0 >>> do j=1,Ny >>> sum = sum + dabs(dv(i,j) .gt. 0.0) * dv(i,j) >>> end do >>> if (sum .gt. 0.0) converged = 0 >>> end do >>> >>> The basic idea is to replace the inner loop conditionals and remove as >>> many of the shared variables as possible. >>> >> >> Yup, keep things pipelined. >> > > That was the idea, though I didn't compile/test the code to be sure it > would work. That and I usually try to avoid real coding when I am tired at > night. Coding and beer don't mix (for me). > > > > > -- > Joseph Landman, Ph.D > Founder and CEO > Scalable Informatics LLC, > email: [EMAIL PROTECTED] > web : http://www.scalableinformatics.com > http://jackrabbit.scalableinformatics.com > phone: +1 734 786 8423 x121 > fax : +1 866 888 3112 > cell : +1 734 612 4615 > -- - - - - - - - - - - - - - - - - - - - - - Nathan Moore Assistant Professor, Physics Winona State University AIM: nmoorewsu - - - - - - - - - - - - - - - - - - - - -
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