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Path: euryale.cc.adfa.oz.au!newshost.carno.net.au!harbinger.cc.monash.edu.au!munnari.OZ.AU!news.mel.connect.com.au!news.mira.net.au!vic.news.telstra.net!act.news.telstra.net!psgrain!iafrica.com!uct.ac.za!quagga.ru.ac.za!howland.erols.net!EU.net!usenet2.news.uk.psi.net!uknet!usenet1.news.uk.psi.net!uknet!dispatch.news.demon.net!demon!awfulhak.demon.co.uk!awfulhak.demon.co.uk!awfulhak.demon.co.uk!not-for-mail From: brian@awfulhak.demon.co.uk (Brian Somers) Newsgroups: comp.unix.bsd.freebsd.misc Subject: Re: 2.1.5-RELEASE sio silo overflows? Date: 12 Sep 1996 11:13:56 +0100 Organization: Coverform Ltd. Lines: 28 Message-ID: <518np4$au@anorak.coverform.lan> References: <50i54c$mq7@yama.mcc.ac.uk> <50kb48$9ok@helena.mt.net> <gergDxG5ry.FGo@netcom.com> <512goo$15q@anorak.coverform.lan> <gergDxK0FH.AFp@netcom.com> NNTP-Posting-Host: localhost.coverform.lan X-NNTP-Posting-Host: awfulhak.demon.co.uk X-Newsreader: TIN [version 1.2 PL2] Greg Andrews (gerg@netcom.com) wrote: : brian@awfulhak.demon.co.uk (Brian Somers) writes: : >Greg Andrews (gerg@netcom.com) wrote: : >: The uart's interrupt trigger is set to *14*??!? : > : >: Man, I thought people had figured that one out by now. : > : >: On OS architectures that carry a lot of latency responding : >: to hardware interrupts (like a multi-user, multitasking OS), : >: a trigger level of 14 is *not* adequate to prevent overflow : >: errors. : > : >[reasoning deleted] : > : >Ah, but FreeBSD is a multi-user, multitasking OS that doesn't carry much : >latency at all ! That's why I can drive a 28.8k modem at a DTR of 115200 : >through an 8250 UART :) It must be about a year since I saw my last : >serial overflow. : > : Driving the modem isn't the issue. It's *receiving* data at high speeds : that has trouble with interrupt latencies, not sending data. Agreed - and my driving includes receiving data :) -- Brian <brian@awfulhak.demon.co.uk> Don't _EVER_ lose your sense of humour....