Managing the workload
If a system is sufficiently well tuned for its applications and
uses to which it is normally put,
you still have a number of options open to you
if you are looking for further performance gains.
This involves managing the system's workload
with the cooperation of the system's users.
If they can be persuaded to take some responsibility with you
(as the system administrator)
for the system's performance,
then significant improvements can usually be made.
Below are some steps that users and administrators
can take to alleviate excessive demands on a system
without reconfiguring the kernel.
If you do not have access to additional hardware
and your system is well tuned,
you may have to implement some of the above recommendations.
Move jobs that do not have to run at a particular time of day
to off-peak hours.
Encourage users to submit jobs using
depending on whether they are one-off
(at or batch)
or periodic jobs (crontab).
Collect data on the average system workload
and publish it to users
so that they are aware of the daily peaks and troughs.
If they have the flexibility to choose when to run a program,
they will know when they can achieve more work.
Adjust the default
of user processes using the
This will set a lower
for all user processes,
and will allow critical jobs with higher priority
to use the CPU more frequently.
Encourage users to reduce the priority of their own processes using
this is especially important for those jobs
that do not perform much
activity -- these CPU-intensive jobs
are likely to monopolize the available processing time.
The default action of the Korn shell (
is to run background jobs at a reduced priority.
Make sure users have not altered this setting
in their .profile or .kshrc files.
Encourage users to kill unnecessary processes,
and to log out when they have finished
rather than locking their screen.
Reduce the maximum number of processes
that a user can run concurrently
by lowering the value of the kernel parameter MAXUP.
For example, MAXUP set to 20 means that a user can
run 19 other processes in addition to their login shell.
Performance tuning case studies
© 2003 Caldera International, Inc. All rights reserved.
SCO OpenServer Release 5.0.7 -- 11 February 2003