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Because WAM and Glue are distributed systems used by many
people, your actions can potentially impact others on the
system, either on purpose or inadvertently. For example, if
one person runs a huge, computing-intensive job, everyone
else on the system has to be scheduled around that job,
slowing them down. In some cases, people have started
large/intensive jobs, then logged off, leaving the rest of
the people on the system to deal with slow response time.
As a bit of background, priorities in Unix (Solaris) can
range anywhere from the highest (-20) (used only by the
sysadmin/superuser), to the lowest (20). Standard login
sessions and associated processes have a priority of 0.
The way we have dealt with that on WAM and Glue is the use of
the nice process, and to a somewhat
lesser extent, the renice process.
The nice process is a way to lower
your job execution priority from that of an interactive
session; this makes it take longer to finish but does not
interfere with other people logged in doing interactive
tasks, hence "playing nice" with the rest of the users on the
system.
The WAM/Glue policy is that you can run whatever you want
(within the University's
Acceptable Use Guidelines) while you're logged in, but if
you want to run something while not being logged on (long
jobs), you need to lower the priority of the job. There is a
background process called niceguy
which monitors the system, and if it finds a job running with
standard terminal priority but with no associated terminal
(tty), the job will be terminated.
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