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From: etb@milton.u.washington.edu (Eric Bushnell)
Newsgroups: comp.sys.apollo
Subject: process priorities (problem?)
Message-ID: <18030@milton.u.washington.edu>
Date: 8 Mar 91 18:14:12 GMT
Sender: etb@milton.u.washington.edu
Organization: University of Washington, Seattle
Lines: 38

Would someone be so kind as to explain how
Domain process priorities work? I have a 
sudden interest, following a strange situation
that occurred yesterday.

An ordinary, unprivileged user wasn't happy
with the priority of his batch job, which he
had started with /usr/bin/nohup. So he used
/etc/renice to change his priority to -20,
the highest priority in BSD unix. Only the
superuser can do this, right? Apparently not.

Unix priority -20 seems to map to a priority
value of 1 in Domain. That was higher than
everything else, so it must have blocked
all other processes. He couldn't stop or
kill it, because the shell was blocked. He
couldn't log out. I tried to get on as root
from another node--no go. Rlogin, telnet, and
crp were all blocked.

Lower level processes seemed to be running.
I was able to use ps //remote_node to see the
process list, but that's about it. I let
it run overnight, in case it finished and
exited normally. It was still going this morning
so I rebooted the node.

I've tried to recreate this in a more controlled
way. So far, all I can tell is that /etc/renice
works strangely.

I remember an earlier gripe about nice. Is this
a known bug? A known feature?

Eric Bushnell
UW Civil Engr
etb@zeus.ce.washington.edu