From owner-freebsd-questions Wed Feb 4 22:55:24 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id WAA23499 for questions-outgoing; Wed, 4 Feb 1998 22:55:24 -0800 (PST) (envelope-from owner-freebsd-questions@FreeBSD.ORG) Received: from starfleet.umd.edu (starfleet.umd.edu [128.8.38.5]) by hub.freebsd.org (8.8.8/8.8.8) with SMTP id WAA23484 for ; Wed, 4 Feb 1998 22:55:16 -0800 (PST) (envelope-from jeanmarc@starfleet.umd.edu) Received: (from jeanmarc@localhost) by starfleet.umd.edu (950413.SGI.8.6.12/950213.SGI.AUTOCF) id BAA03701 for freebsd-questions@freebsd.org; Thu, 5 Feb 1998 01:26:18 -0500 From: "Jean-Marc Henriette" Message-Id: <9802050126.ZM3699@starfleet.umd.edu> Date: Thu, 5 Feb 1998 01:26:18 -0500 X-Mailer: Z-Mail (3.2.3 08feb96 MediaMail) To: freebsd-questions@FreeBSD.ORG Subject: Real time on freebsd Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG X-To-Unsubscribe: mail to majordomo@FreeBSD.org "unsubscribe questions" Thanks for all the responses I got! Saldy I didn't do a good enough job of specifying what I wanted to do, hence I'll restate my question by including a bit more info. I work at a lab here at the university of maryland which is involved in the design of a space robot. In order for this robot to function properly, we have to be able to run a function at a constant rate. Since this rate plays back into the algorithm itself, it is important that this loop stay at a constant 200 hz. The accuracy of this loop must be within a percent or so. The original question was wether FreeBSD had some sort of way to make sure that this loop rate stays constant over time. Most Real Time implementation that I have seen actually use the clock interupt as a method of triggering these functions, thus making the system fairly deterministic. How hard would this be to implement on FreeBSD?? I've thought of using the alarm signals, but I am unsure of the latency involved with signals, as well as the accuracy of the clock it uses. thanks again! Jean-Marc Henriette University Of Maryland Space Systems Lab. http://www.ssl.umd.edu