Date: Thu, 28 Jan 1999 13:07:08 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: Duncan Barclay <dmlb@ragnet.demon.co.uk> Cc: hackers@FreeBSD.ORG, wes@softweyr.com, dyson@iquest.net, Kevin Day <toasty@home.dragondata.com> Subject: Re: High Load cron patches - comments? Message-ID: <199901282107.NAA11042@apollo.backplane.com> References: <XFMail.990128185136.dmlb@computer.my.domain>
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: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 <dillon@backplane.com> To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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