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From: Marcin Skoczylas (Marcin.Skoczylas_at_[hidden])
Date: 2006-07-05 10:54:48


Dear open-mpi users,

I saw some posts ago almost the same question as I have, but it didn't
give me satisfactional answer.
I have setup like this:

GUI program on some machine (f.e. laptop)
Head listening on tcpip socket for commands from GUI.
Workers waiting for commands from Head / processing the data.

And now it's problematic. For passing the commands from Head I'm using:
while(true)
{
    MPI_Recv...
   
    do whatever head said (process small portion of the data, return
result to head, wait for another commands)
}

So in the idle time workers are stuck in MPI_Recv and have 100% CPU
usage, even if they are just waiting for the commands from Head.
Normally, I would not prefer to have this situation as I sometimes have
to share the cluster with others. I would prefer not to stop whole mpi
program, but just go into 'idle' mode, and thus make it run again soon.
Also I would like to have this aggresive MPI_Recv approach switched on
when I'm alone on the cluster. So is it possible somehow to switch this
mode on/off during runtime? Thank you in advance!

                            greetings, Marcin