Timing

New users interested in using the nersp for research purposes should be aware that in interactive mode with a g77 compiled code, the code runs slower than on a PC when run interactively There will be a considerable overhead involved in converting existing code to good IBM code. The result will probably be a better code less likely to produce erroneous results and it is much more convenient to have the staff run it 24 hours a day rather than your own PC, but .-- nersp timing --

llsubmit

Large jobs need to be submitted to the load leveler to keep from adversely affecting the other users on the system. Details and problems are described below. Note that most names have had the extension .txt added to them for display purposes.

The system command llsubmit is described by Tarrie Van Horn in two e-mail messages. The first is

  1. llsubmitexample#1.txt. The command file used by this is Attach/square. I have added txt to the name for it to display here. Tarrie used it without the txt. In general on my rci account, I used the extension com for this file. Before this first example Attach\squares.f was compiled and linked interactively as described in the txt file. The resulting a.out file was given to llsubmit. A frequent problem involves expectations on the part of the linker as to the other codes that will be present for use when the job is actually run.
  2. loadlevelerexample#2.txt. The command file is Attach\dump, The arguments file is Attach\howdy. The code is Attach\xdump. This differs from the first in the presence of an arguments parameter in the file submitted, and in the name of the executable.
  3. The man page for llsubmit is llsubmit.txt.
  4. An alternative to llsubmit that keeps the job in the current shell is described in the man page nice.txt.

My colleague Steve Alexander and I have made reasonably extensive use of this command. Two examples are

    1. rci/znew.com

#@ account_no = rci003

#@ class = medium

#@ error = znew.err

#@ executable = znew The code has already been compiled and linked. This file has been removed to save space.

#@ job_name = zjob

#@ input = znew.in --- Input data

#@ output = znew.out --- trouble with this output

#@ queue

    1. rci\zexpand.com

#@ account_no = rci003

#@ class = medium

#@ error = zexpand.err

#@ executable = zexpand The code has already been compiled and linked. This file has been removed to save space.

#@ job_name = zjob

#@ input = zexpand.in

#@ output = zexpand.out -- This code produced good result

#@ queue

 

It is our standard practice to form the executables such as znew, and zexpand interactively and to test them with small amounts of input before submitting the jobs.

Very few people use llsubmit. This means that it frequently has problems, both from users who forget the directions and from staff who install things that do not work. The file email.txt may shed some light on this while giving names and addresses to go to for help.