Thanks for your suggestion. I am trying MPI_Wtime to see if there is any difference.
Linbao On Thu, Oct 21, 2010 at 1:37 AM, jody <jody....@gmail.com> wrote: > 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 > > > > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users >
