Separate HTML for Basic Foil 22 Implementation of MPSHIFT(+1, SOURCE,DEST)

Basic HTML version of Foils prepared 2 September 1997

Foil 22 Implementation of MPSHIFT(+1, SOURCE,DEST)

From CPS615 Laplace Example -- Programming Models and Performance CPS615 Basic Simulation Track for Computational Science -- Fall Semester 97. by Geoffrey C. Fox

Consider for example, shift to right

Then Processors 0 .. Nproc-2 Send to right

Processors 1 .. Nproc-1 Receive from left

We can't necessarily send all messages and then receive all messages. "Standard" send can be "blocking" i.e. will not return unless receive completed by destination processor. In this case, we can deadlock as all "hang" after send, waiting for receive

So we are more careful