"I was thinking of something like a barrier+probe+cancel (if necessary)."
There are no non-blocking collective communications guaranteed by MPI-2. DCMF (which sits beneath MPI on BlueGene) supports something like this, but for portable code you are SoL. A -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-dev/attachments/20100507/0c811369/attachment.html>
