From wilsom3 Mon Mar 31 10:30:49 1997
Received: from vccnorth22.its.rpi.edu (wilsom3@vccnorth22.its.rpi.edu [128.113.69.132])
	by mail1.its.rpi.edu (8.8.5/8.8.5) with ESMTP id KAA27186
	for <brings>; Mon, 31 Mar 1997 10:30:49 -0500
From: Michael Wilson <wilsom3>
Received: (wilsom3@localhost) by vccnorth22.its.rpi.edu (8.6.9/8.6.4) id KAA19728 for brings; Mon, 31 Mar 1997 10:30:48 -0500
Date: Mon, 31 Mar 1997 10:30:48 -0500
Message-Id: <199703311530.KAA19728@vccnorth22.its.rpi.edu>
To: brings
Subject: SP2 environment questions
X-UIDL: 7ba60babf5e353255892f2bc649c0f55
Status: R

Selemr,
	I guess the easiest way to send the questions through is just to
pass them through you.  (I could stop by your office, but timing is a
problem.)
	First and foremost, I need to know what kind of I/O is available.
I was hoping to have one specific process reading and writing a file.  On
most MPI models, all processes can do file I/O; on a few more restrictive
ones, only process 0 can do I/O.  I'm assuming that I can use process 0
to do my I/O.  I don't need any of the others to do it.  If there is a
problem with a process reading an initial file or writing a final file,
then I've no idea how to get this to work.
	Second, and almost as important, I need to know something more
about the environment it will run on.  If the SP2 is running some form
of UNIX, that would be ideal.  I need to have some way to have whoever
is running my program tell it to stop and save it's work, probably by
sending an interrupt signal (CTRL-C).  If the SP2 is running some form of
UNIX, they'll have a signal library available with which I can write some
way to tell my program to save it's work and stop.  (Since I don't know
how long it would take to simply run the program, I can't assume that they
can just start it and let it run until it finishes!  Especially not if it
could take 4-24 hours....)
	Assuming it is running under some kind of UNIX and has a signal
library, I just need some detail about the specific library they have.
Different UNIX systems have different ways to install signal handlers,
mask signals, etc.  I'm familiar with most methods, but I don't know which
one they are using!
						Mike Wilson
						(wilsom3@rpi.edu)
PS - I've been doing some hand verification of the program I wrote, and
there are some inefficiencies I'm working out.  It should work, but I want
it to work better.