Path: utzoo!mnetor!uunet!husc6!bloom-beacon!gatech!hao!ames!pasteur!ucbvax!hplabs!hpda!hpcupt1!davel
From: davel@hpcupt1.HP.COM (Dave Lennert)
Newsgroups: comp.unix.wizards
Subject: Re: UNIX for realtime
Message-ID: <5960002@hpcupt1.HP.COM>
Date: 15 Jan 88 04:35:25 GMT
References: <449@aati.UUCP>
Organization: Hewlett Packard, Cupertino
Lines: 17

> In instrumenting a vanilla 4.2 BSD kernel, for example, there were
> windows of up to 4 milliseconds (14,000 instructions on the particular
> machine) where the O/S could not allow a process to execute.

The window I measured was more than 1 SECOND.  These measurements and
the HP-UX kernel mods to fix them are discussed in:

"Decreasing Realtime Process Dispatch Latency through Kernel Preemption",
USENIX Conference Proceedings, Summer 1986, pp. 405-413.

For a discussion on the other needed real time facilities that are
provided in HP-UX see:

"UNIX for Real Time", UniForum Conference Proceedings, January, 1987,
pp. 219-230.

-Dave Lennert   HP   ihnp4!hplabs!hpda!davel    uunet!hpda!davel