"Nice" or not to "nice" large jobs

[Sheryl Coppenger]

Historically (since before I worked here), there was a policy for
users running large jobs which ran along these lines:

	1)  Run them in the background

	2)  Start them up with "nice" to lower priority

	3)  Only one such job on a machine

I have a user challenging that policy on the grounds that UNIX
will take care of it automatically.  I am aware that some systems
have that capability built in to the kernel, but I am not sure
to what extent ours do or how efficient they are.  I have looked
in the manuals for both of our systems (Sun and HP) and in the Nemeth 
book, but they are pretty sketchy.  In my previous job, I was doing
support for realtime systems written on HP 9000/800-series and I
am fairly sure about what happens in realtime but that doesn't
help in this case.  

What are other system administrators doing about this issue?  Can
any internals experts point me to something definitive about my
particular OSs?  We have

	HP 9000s - 300, 400 and 800 series, running HPUX 7.0
	SUN 3s running 4.1 and SUN 4s running 4.1.1

I'm looking for the specific, not the general.

If there are good reasons for the policy, I want to be able to
justify it as well as enforce it.

Thanks in advance

--

  Sheryl L. Coppenger        
  sheryl at seas.gwu.edu           
  (202) 994-6853