From owner-freebsd-hackers Thu Jan 28 13:07:35 1999 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id NAA16006 for freebsd-hackers-outgoing; Thu, 28 Jan 1999 13:07:35 -0800 (PST) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from apollo.backplane.com (apollo.backplane.com [209.157.86.2]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id NAA16001 for ; Thu, 28 Jan 1999 13:07:33 -0800 (PST) (envelope-from dillon@apollo.backplane.com) Received: (from dillon@localhost) by apollo.backplane.com (8.9.2/8.9.1) id NAA11042; Thu, 28 Jan 1999 13:07:08 -0800 (PST) (envelope-from dillon) Date: Thu, 28 Jan 1999 13:07:08 -0800 (PST) From: Matthew Dillon Message-Id: <199901282107.NAA11042@apollo.backplane.com> To: Duncan Barclay Cc: hackers@FreeBSD.ORG, wes@softweyr.com, dyson@iquest.net, Kevin Day Subject: Re: High Load cron patches - comments? References: Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG :Speaking as an electronic engineer who uses feedback in circuits all the :time: : :One thing to watch out for when you have rate-feedback and a limiter is :essentially designing a unstable or chaotic system. The limit acts as a :non-linearity in the system feedback function which is usually a bad thing. :Non-linearities will at best open the feedback loop and at worst cause it to :thrash around like a mad thing. Similarly, if you have too many feedback loops :(i.e. rate and number) the feedback can start to oscillate... : :These effects may not be visible because the time constants of the feedback :systems are likely to be longer than the process creation rate. : :All of these are testable but it is easy to generate an unstable system by :changing time constants. : :Duncan Think of it as the current-sense (aka limiting) resistor in a switching power supply. -Matt :--- :________________________________________________________________________ :Duncan Barclay | God smiles upon the little children, :dmlb@ragnet.demon.co.uk | the alcoholics, and the permanently stoned. :________________________________________________________________________ : Matthew Dillon To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message