[mpich-discuss] All the processes are not using almost same cpu

[Rhys Ulerich]

> I am using mpich2 with fortran. when I am running my mpi code, on my desktop
> (which has 8 processors), initially all the processors are using almost same
> cpu % (around 70 %) ( checked by  top command ). but as time passes, % cpu
> usage of one processor raises to almost 100% and % cpu usage of others down
> gradually.
> Earlier my code was working fine, but I modified it to optimize. What could
> be the possible reason for this problem .

Do you have one rank (say rank zero) which does more work than the
others?  Possibly the other ranks are waiting on one rank to make
progress...

- Rhys