FW: MPICH, malloc, and my impending assault of one (1) beowulf cluster

Chris Richard Adams chrisa at ASPATECH.COM.BR
Thu Aug 2 09:39:54 PDT 2001

-----Original Message-----
From: Chris Richard Adams 
Sent: Thursday, August 02, 2001 12:38 PM
To: 'mundy erik'
Subject: RE: MPICH, malloc, and my impending assault of one (1) beowulf

Hi Erik - 

Admiting your abusiveness is the first and hardest step toward
healing..congratulations! I don't have a response to your problem, but
perhaps will run into that soon. Unfortuately I am just trying to get
the pi code to run.  If I may ask...

1) did you use the example that comes with the beowulf install - found
in \usr\mpi-beowulf\examples? That directory has a pi example, but I
can't get the Make to work.  Did you succeed? Can I just run MpiCC -o
pisamp cpi.c?

2.) DO you know of any documentation for those examples, or perhaps
could you share a reference to an MPI example.  I know C, but nothing
about MPI and just want some hello world examples. 


-----Original Message-----
From: mundy erik [mailto:erik.mundy at HAMPTONU.EDU]
Sent: Wednesday, July 18, 2001 4:35 PM
To: 'beowulf at beowulf.org'
Subject: MPICH, malloc, and my impending assault of one (1) beowulf

Hello, my name is Erik, and I am an MPICH abuser.

	I am running a simple one master, two slave Beowulf test
RHL 6.1, kernel 2.4.4, MPICH 1.2.1, NFS mount from master to slave on
PII 400's.  MPICH is giving me some serious headaches - every MPI
program I
execute with a malloc in it crashes with the good old "p4 error:
SIGSEGV: 11" message.  I have been experimenting with the test programs
come with MPICH for simplicity; for example, 'cpi' runs well on all
computers.  It
calculates pi, and I rejoice.  Mpptest also works without a problem
any two of the three computers.  But when I try to mpirun "sendrecv" or
"overtake" from examples/test/pt2pt (both of which use a malloc), MPICH
gives it the good old college try and then throws me the errors.
Normally I
would just try to do as much as humanly possible to ignore this problem,
the code that this beowulf was designed for works when I execute it on
computer, and crashes rather spectacularly with the segmentation
error when I try to mpirun it, even on just one computer, leading me to
think that there is some sort of conflict between MPICH and malloc.  
	Granted, these computers aren't exactly state-of-the-art - each
only 128M ram with ~400M swap.  But that should be more than enough to
execute those simple examples.  Has anyone had trouble with the Linux
version of malloc in the past in a situation like this?  If you shudder
you hear the words "malloc" and "MPICH" used in the same sentence,
email me back.  This might be a bit difficult to track down, and I'm
not the best man for the job, all I did was build a beowulf :).  I've
been on this list for the last two months but it's taught me that if
can help its probably you guys.  I am EXTREMELY appreciative of any
assistance you can offer. 


erik.mundy at hamptonu.edu

PS - also, I should mention that yes, the code I am trying to run WAS
designed for use with MPI, and yes, I did patch MPICH with the bug fixes
from the Argonne page.  Sorry to take the obvious 'he's so dumb!'
away... I'm hoping there's one more that maybe I'm just missing :) 

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