[mpich-discuss] Running the processes just in the nodes

[Ralph Butler]

Below is a quick demo of how to do such things.

First, show 3 machines in the mpd ring:

(bp400:70)% mpdtrace
bp400
bp403
bp401


Now show that by default 3 processes will run on all the machines:

(bp400:71)% mpiexec -l -n 3 hostname
0: bp400
1: bp403
2: bp401


Now use the -1 (minus 1) arg to cause the first process to locate on  
the second host.  Of course
the last one comes back to the first host, which may still be  
undesirable:

(bp400:72)% mpiexec -l -1 -n 3 hostname
2: bp400
0: bp403
1: bp401


Now, create a machine file (named mf) and prepare to use it.  It will  
map ranks to hosts.
(bp400:74)% vi mf
(bp400:75)% cat mf
bp401
bp403
bp401

Now use that machinefile to run the procs on hosts other than bp400.
(bp400:76)% mpiexec -l -machinefile mf -n 3 hostname
0: bp401
1: bp403
2: bp401


There are other ways to accomplish this as well using other options  
documented in the user guide.

--ralph


On MonSep 22, at Mon Sep 22 7:36AM, Ariovaldo de Souza Junior wrote:

> I would like to know if is that possible to run the processes just  
> in the nodes, leting the master node free for other tasks. For  
> example, I have a small cluster with 9 core 2 quad, I would like to  
> run the calculations just in 8 computers. I have tried editing the  
> mpd.hosts commenting the line that points the name of the master  
> node but it was useless, it started anyway. Does anyone have a ligh  
> to sheed over this issue?
>
> Thanks from now,
>
> Ariovaldo de Souza Junior
> Federal University of Amazonas
>