Re: [Pympi-users] starting from scratch

[Pat M. <pat...@ll...>]

I've answered build questions below, but thought I would add a
bit on pyMPI in the classroom first...

I've used pyMPI in a classrooom environment.... I think its a great
way to learn about MPI without the hassle of doing it with C or
Fortran.   I was able to concentrate on the parallelism instead of
burying the students in the opaque API requirements [but Prof Miller,
whats a communicator? whats a tag?  why do I have to specify the type?]

This is particularly spiffy since pyMPI hides a lot of spurious
arguments, so you can introduce point-to-point with something as
simple as:

% mpirun -np 2 pyMPI
Python 2.4 (pyMPI 2.4b1) on linux2
Type "help", "copyright", "credits" or "license" for more information.
Python 2.4 (pyMPI 2.4b1) on linux2
Type "help", "copyright", "credits" or "license" for more information.
 >>> from mpi import *
 >>> if rank == 0:
...    send("hello",1)
... else:
...    print recv()
...
('hello', <MPI_Status Source="0" Tag="0" Error="0" MPI: no errors\>)
 >>>

The good news is that students (after using only pyMPI) were able
to transfer all their knowledge back to C and FORTRAN parallel
programming.

Cheers!
Pat

--------- %< --------------------------------------------------

The basic requirements for pyMPI are (not surprisingly ;-) ),
Python and a MPI C compiler (or appropriate includes and libraries).

I think there is a debian package for LAM MPI (see
http://packages.debian.org/testing/source/lam )

This installs several things, but the only ones you likely
need to know will be lamboot, mpirun, mpicc.

Now make sure the Python was installed with development options:
You can run this command to find out python's install root...

% python -c "from distutils.sysconfig import parse_makefile, get_makefile_filename; print parse_makefile ( get_makefile_filename ( ) ) ['prefix']"
/usr/local

Now look to see if the install things are there...
(the below assumes python2.4, the path is similar
for 2.1, 2.2, 2.3).

% ls /usr/local/include/python2.4/Python.h
/usr/local/includ
I've used pyMPI in a classrooom environment.... I think its a great
way to learn about MPI without the hassle of doing it with C or
Fortran.   I was able to concentrate on the parallelism instead of
thee/python2.4/Python.h

% ls /usr/local/lib/python2.4/config
Makefile  Setup.config  config.c     install-sh*     makesetup*
Setup     Setup.local   config.c.in  libpython2.4.a  python.o

If you don't see those files, then you may need to build Python
from scratch.

Now to build a version of pyMPI that uses those tools....
First, use which to make sure you are using.

% which mpicc
/usr/local/bin/mpicc

% which python
/usr/local/bin/python

% cd pyMPI-2.4b1
% env CC=/usr/local/bin/mpicc ./configure --prefix=/where/ever --with-python=/usr/local/bin/python
% make
% make install
% make check

using the env CC=xyz ensures that the configure will pick the parallel
mpi compiler you want [similarly the --with-python].  If you don't pick
a installation prefix, it is supposed to default to the same place
python is installed.

If you download the latest and greatest directly from CVS, you need to do
% ./boot
before you do the
% ./configure
[this bootstraps the autoconf environment].

---------%<----------------------------------

To run, you should do

% lamboot
% mpirun -np 2 pyMPI myscript.py

if you want to run across a cluster, you set up a machines file
in bhost format (do a % man bhost  for info)

% cat machines
tux132
tux147

You also need to either have to be running rsh or you must set up
ssh keys for passwordless login.

% ssh-keygen -t dsa
<blah blah blah>
% cat ~/.ssh/id_dsa.pub >> ~/.ssh/authorized_keys


If you have any problems, let me know.

Cheers,

Pat

-- 
Pat Miller | (925) 423-0309 | http://www.llnl.gov/CASC/people/pmiller

In order that people may be happy in their work, these three things are
needed: they must be fit for it; they must not do too much of it; and they
must have a sense of success in it. -- John Ruskin