Xref: utzoo comp.unix.questions:8568 comp.unix.wizards:10221
Path: utzoo!utgpu!attcan!uunet!husc6!think!bloom-beacon!tut.cis.ohio-state.edu!bgsuvax!nijhawan
From: nijhawan@bgsuvax.UUCP (Sandeep Nijhawan)
Newsgroups: comp.unix.questions,comp.unix.wizards
Subject: A question on Unix/Ultrix CPU scheduling
Keywords: cpu, scheduling, kernel, nice
Message-ID: <2724@bgsuvax.UUCP>
Date: 3 Aug 88 23:29:11 GMT
Organization: Bowling Green State University B.G., Oh.
Lines: 23




I 've been doing some work with the Ultrix (V2.0-1) cpu scheduling
algorithms and have the following question(s) -

	If the Super User were to increase the priority of a process by
using /etc/renice to the maximum possible (-20) and then run a program
with an infinite loop (completely cpu-bound), would any other user
process on the system get the cpu at all until the priority of the super
user's process went below PUSER ? Why?

	I modified setpri() in kern_synch.c so that a process with a
certain uid would always be given a priority of (PUSER - 1) irrespective
of its p_cpu value. After I rebuilt the kernel and ran an infinte-loop
process with that uid, I could still run other processes with other uids
though they ran much less frequently. Any ideas about what's going on?

	Any help would be much appreciated. Yes, I have Bach.

Sandeep

[I am sorry if this got posted twice]