No, the root processor can be different for every broadcast, but for a same broadcast every process involved must know who the root is. That's the only condition MPI imposes.
George. On Apr 29, 2013, at 13:15 , giggzounet <giggzou...@gmail.com> wrote: > Hi, > > I'm new on this list. I'm using MPI for years but I don't have written a > lot of code with MPI. Therefore is my question perhaps ridiculous: > > I'm using a Computational Fluid Mechanics (CFD) Solver. This Solver uses > MPI to exchange the data between the different partitions. In this > solver the "root processor" is always the processor 1. So this proc > reads the input, broadcast a lot of things and writes the output. > > During a time step the solver computes the reference pressure at a > point. This computation is done on a processor, which may not be the > root processor. Therefore after the computation a broadcast of the value > is necessary. For the moment in the code the broadcast is done with the > processor, where the reference pressure is computed, as root processor > (and not with the standard "root processor"). > > Is it false ? Must the root processor be the same during a computation > for all broadcasts ? > > Best regards, > Guillaume > > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users
