Petrol

Code

petrol.tar.gz

Quick Start Guide

The file that contains the fitness() function is fitness.c. You are passed a pointer to Individual structure (petrol.h) that has the following fields: 

  int    *chrom;
  int     chromLen;
  double  fitness;

The chrom field is the encoded individual of the population of a length defined by chromLen.

Once the fitness function has been implemented both petrol and petrolslave need to be remade. In order to do this though, you need to make sure your shell environment has both PVM_ROOT and PVM_ARCH defined. Here is an example .cshrc fragment that shows how to set them:

if ( -d ~/pvm3 ) then
   setenv PVM_ROOT ~/pvm3
endif

set pvm = ( )
if ( $?PVM_ROOT ) then
     if ( -x $PVM_ROOT/lib/pvmgetarch ) then
        setenv PVM_ARCH `$PVM_ROOT/lib/pvmgetarch`
        set pvm = ( $PVM_ROOT/lib/$PVM_ARCH $PVM_ROOT/bin/$PVM_ARCH )
     endif
endif

...

set path = ( ~/bin $pvm /bin /usr/bin /usr/local/bin /usr/X11R6/bin )

...

In order for this to work you need to create a pvm3 directory in your home directory with symbolic links from that directory to the installed PVM location:

cd
mkdir pvm3
cd pvm3
ln -s ~pvm/lib .
ln -s ~pvm/include .
ln -s ~pvm/man .
mkdir bin

Another thing to add to your .cshrc could be the following environment setting to allow you to read the PVM man-pages:

setenv MANPATH /usr/man:/usr/local/man:/usr/X11R6/man:$PVM_ROOT/man

At this point you should test your .cshrc by restarting your current shell and execute echo $PVM_ROOT $PVM_ARCH $path.

Back in the petrol directory, you need to do a make install. This will build all the objects for petrol and petrolslave (all suffixed with $PVM_ARCH.o), link, and install them into ~/pvm3/bin/$PVM_ARCH. For each architecture, you need to build binaries on those machines (i.e., on the DEC stations, build petrol, on the Linux boxes, build petrol, etc.).

Once all the binaries have been built, PVM needs to be started and the host machines need to be added to the virtual machine. There are two ways to add hosts. The first is to start PVM and enter the hosts by using the add command:

% pvm
pvm> add dws007
1 successful
                    HOST     DTID
                  dws007    80000
pvm> conf
2 hosts, 1 data format
                    HOST     DTID     ARCH   SPEED
                  batman    40000    LINUX    1000
                  dws007    80000     PMAX    1000
pvm>

The other way is to create a file with each line containing a name of a host and start PVM with the name of the file as the command line argument.

Finally, execute petrol from your shell (not in pvm). This will start a petrolslave on each of the hosts in your virtual machine and start a run of how every many generations specified.

IMPORTANT NOTE: If for some reason you stop petrol in the middle of a run, you need to cleanup the petrolslave processes by hand. To do this, in the pvm console, do a ps -a and kill each of the DTID numbers listed. Or, if you halt the machine, it will kill them for you.

Petrol Options

petrol [-b int] [-c float] [-g int] [-l int] [-m float]
       [-n] [-o string] [-p int] [-s int] [-v]

-b PVM block size (default 10)
-c Probability of crossover (default 0.66)
-g Number of generations (default 500)
-l Chromosome length (default 100)
-m Probability of mutation (default 0.001)
-n Minimize (default FALSE)
-o Output to a file (default stdout)
-p Population size (default 100)
-s Random seed (default current time)
-v Print extra information (verbose)

Code Structure

petrol.h

The Population and Individual structures are defined in this file, along with all the functions and their parameters.

petrol.c

This file contains the startup code and command line processing. The important part is in main() where PopulationRun() is called.

population.c

All the Population functions are here. PopulationRun() is the main loop of petrol. PopulationGeneration() is where the selection and crossover takes place.

report.c

If any output needs to be changed, this is the file to modify. ReportInitial() is called before the first generation, ReportGeneration() is called after every new generation, and ReportDone() is called after all the generations have been created. These three functions are called from PopulationRun() in population.c.

petrolslave.c and pvmfitness.c

Both of these files perform the communication via PVM. PVMFitness() spawns off the petrolslave processes, sends the Individual structures, and fills in the resulting fitness values. All petrolslave does is respond to work requests and runs fitness() on the remote machines.

utils.h and utils.c

These contain various utility functions used throughout petrol.

References

A good website to check out is the Parallel Virtual Machine (PVM).
Eric Blood
eblood@cs.unr.edu
Last modified: Thu Sep 26 14:40:08 1996