Path: utzoo!utgpu!attcan!uunet!lll-winken!lll-lcc!ames!pasteur!ucbvax!VENUS.YCC.YALE.EDU!LEICHTER
From: LEICHTER@VENUS.YCC.YALE.EDU ("Jerry Leichter ", LEICHTER-JERRY@CS.YALE.EDU)
Newsgroups: comp.os.vms
Subject: V5.0 - Where is NULL proc?
Message-ID: <8807291946.AA04753@ucbvax.berkeley.edu>
Date: 29 Jul 88 18:35:00 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 19


	I have noticed that when I type "SHOW SYSTEM" under version 5.0, the
	NULL process isn't listed (the first one is SWAPPER).  Could someone
	familiar with this explain what now substitutes for the NULL process?

Actually, in some sense the null process is still there; but it's been made
invisible to GETJPI.

NULL had two purposes in life:  To make sure there was always a process for
the scheduler to run (thus eliminating a special case); and as a handy way
to determine unused time on the system, since it would all get "used" by
NULL.  With multiprocessors, a single null process can't server either of
these purposes:  There many be a number of processors each needing a "NULL"
process to run; and the idle time has to be the sum of the idle times for
each processor.  So what was visible as "the NULL process" - which was always
a hack anyway; the NULL process's code was assembled into VMS, was all up in
system space, and never had any real process context - has now been re-orga-
nized into appropriate "idle loops" which it's not useful to cover with a
"process" facade any more.
							-- Jerry