[mpich-discuss] separate working directory for each process

Zachary Stanko zstanko at usgs.gov
Fri Aug 17 18:44:22 CDT 2012


 My application does not run because each process is trying to ope the 
same output file. How can I specify a separate working directory for each 
process so there is no conflict.
Something like: mpiexec -n 1 myapp inp-file : -n 1 -dir c:\temp\scratch1 : 
-n 1 -dir c:\temp\scratch2 : -n 1 -dir c:\temp\scratch3

The application is an optimization that only needs to run on the host 
machine. The three workers (different cores on the same machine) only need 
to evaluate a simulation model embedded in the application.
The simulation model, however, needs to produce an output file whose name 
cannot be changed so I just want it to be output to a different directory 
for each worker.

Is the first process always going to be the master with rank 0?
Do I need a copy of the application and input file in each of the working 

If I added myapp inp-file to each of the worker commands, would the whole 
application just run separately on all four processors or would they sync 
up and know that the workers only have a specific task?

mpiexec -n 1 myapp inp-file : -n 1 -dir c:\temp\scratch1 myapp inp-file: 
-n 1 -dir c:\temp\scratch2 myapp inp-file: -n 1 -dir c:\temp\scratch3 
myapp inp-file

I have tried this latter option with both 3 and 6 workers (I am running on 
an eight core processor) but do not seem to be getting any speedup so I'm 
wondering if I am doing this wrong.

Thank you for your time,

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