Return to BSD News archive
Newsgroups: comp.unix.bsd
Path: sserve!manuel.anu.edu.au!munnari.oz.au!spool.mu.edu!uwm.edu!zaphod.mps.ohio-state.edu!sdd.hp.com!elroy.jpl.nasa.gov!ames!agate!doc.ic.ac.uk!cc.ic.ac.uk!imperial.ac.uk!vulture
From: vulture@imperial.ac.uk (Thomas Sippel - Dau)
Subject: Re: Unix with real time performance ?
Message-ID: <1992Oct29.204319.12512@cc.ic.ac.uk>
Sender: vulture@carrion.cc.ic.ac.uk (Thomas Sippel - Dau)
Nntp-Posting-Host: cscgc
Reply-To: cmaae47@imperial.ac.uk
Organization: Imperial College of Science, Technology and Medicine
References: <1992Oct10.211721.5925@decuac.dec.com> <1123@kommu.UUCP>
Date: Thu, 29 Oct 92 20:43:19 GMT
Lines: 30
In article <1123@kommu.UUCP>, otto@norisc.erls01.siemens.de (Otto Niesser) writes:
- We have developed 'SORIX 386/486' an AT&T SVR4.0 based real time UNIX system.
-
- On a 80386 CPU running at 33 MHz we guarantee an interrupt latency time
- of at most 135 us and a context switch latency of at most 325 us.
-
- That means if an interrupt arrives it takes at most 135 us until
- the execution of the interrupt handler starts.
Now let me see, a v32bis modem running v42 or MNP4 will send you a character
14400/8 = 1800 times a second, or every 555 microseconds (...). You also get
a transmit interrupt every 555 microseconds. A PC has two serial ports.
I guess I need large amounts of memory or applications with fast buffer
handling if I want to run an IP (slip) gateway at full tilt over these
and still do some useful work.
But still, would be nice if you could run such a setup and report how much
useful CP was left for other processes. Ah, and be sure you use the basic
serial ports, not any of these nice 4 port adapters with a 68000 on them...
Thomas
--
*** This is the operative statement, all previous statements are inoperative.
* email: cmaae47 @ ic.ac.uk (Thomas Sippel - Dau) (uk.ac.ic on Janet)
* voice: +44 71 589 5111 x4937 or 4934 (day), or +44 71 823 9497 (fax)
* snail: Imperial College of Science, Technology and Medicine
* The Center for Computing Services, Kensington SW7 2BX, Great Britain