[petsc-users] Problem when switching from debug to optimized

[Bogdan Dita]

  Hello,

  Until a few days ago I've only be using PETSc in debug mode and when I
switch to the optimised version(--with-debugging=0) I got a strange
result regarding the solve time, what I mean is that it was 10-15 %
higher then in debug mode.
  I'm trying to solve a linear system in parallel with superlu_dist, and
I've tested my program on a Beowulf cluster, so far only using a single
node with 2 quad-core Intel processors.
  From what I know the "no debug" version should be faster and I know it
should be faster because on my laptop(dual-core Intel) for the same
program and even the same matrices the solve time for the optimised
version is 2 times faster, but when I use the cluster the optimised
version time is slower then the debug version.
  My quess is that this has something to do with MPI. Any thoughts?


  Best regards,
  Bogdan Dita