Hi I don't know the reason for the strange behaviour, but anyway, to measure time in an MPI application you should use MPI_Wtime(), not clock()
regards jody On Wed, Oct 20, 2010 at 11:51 PM, Storm Zhang <storm...@gmail.com> wrote: > Dear all, > > I got confused with my recent C++ MPI program's behavior. I have an MPI > program in which I use clock() to measure the time spent between to > MPI_Barrier, just like this: > > MPI::COMM_WORLD.Barrier(); > if if(rank == master) t1 = clock(); > "code A"; > MPI::COMM_WORLD.Barrier(); > if if(rank == master) t2 = clock(); > "code B"; > > I need to measure t2-t1 to see the time spent on the code A between these > two MPI_Barriers. I notice that if I comment code B, the time seems much > less the original time (almost half). How does it happen? What is a possible > reason for it? I have no idea. > > Thanks for your help. > > Linbao > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users >
