Re: what's this "nice" unix thing?

Frank Mayhar (
Fri, 23 May 1997 10:38:28 -0700 (PDT)

Collin Ong wrote:
> Am I doing something wrong or is there no way to get deschall to drop to
> single digit CPU % when something else runs. Most normal processes run
> at NICE level 0.
> Can anything be done to further lower deschall's CPU usage when something
> else is running? If so, I can get a bunch of workstations on the task
> this weekend.

This is a result of the way "nice" is implemented in the Unix scheduler.
There have been discussions of this before, both here and elsewhere, but
suffice it to say for now that, unless your Unix has been modified to fix
this, niced processes still compete with non-niced processes, just less
heavily. They use less of the CPU, but they still get run. It's part of
the fairness algorithm (a process that hasn't been run in a long time is
more likely to be run as time passes).

Frank Mayhar
              Tandem Computers, Inc.
              390 N. Sepulveda Blvd. Ste. 3050, El Segundo, CA 90245
	      (310) 414-3106