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Path: euryale.cc.adfa.oz.au!newshost.anu.edu.au!harbinger.cc.monash.edu.au!news.cs.su.oz.au!metro!metro!asstdc.scgt.oz.au!nsw.news.telstra.net!act.news.telstra.net!imci3!newsfeed.internetmci.com!tezcat.com!news.ner.bbnplanet.net!howland.reston.ans.net!swrinde!elroy.jpl.nasa.gov!usc!math.ohio-state.edu!news.cyberstore.ca!skypoint.com!newshub.tc.umn.edu!zib-berlin.de!irz401!uriah.heep!news From: j@uriah.heep.sax.de (J Wunsch) Newsgroups: comp.unix.bsd.freebsd.misc Subject: Re: Buffer overruns on sio1 serial device? Date: 8 Jun 1996 22:03:31 GMT Organization: Private BSD site, Dresden Lines: 28 Message-ID: <4pctbj$ma@uriah.heep.sax.de> References: <4opne5$pn8@mips.infocom.com> Reply-To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch) NNTP-Posting-Host: localhost.heep.sax.de Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit X-Phone: +49-351-2012 669 X-PGP-Fingerprint: DC 47 E6 E4 FF A6 E9 8F 93 21 E0 7D F9 12 D6 4E paulr@infocom.com (Paul Retherford) wrote: > I am trying to set up a FreeBSD 2.1 server to receive incoming data > using the high speed serial device. The data arrives through a satellite > feed at 115k bps. The kernel recognizes the 16550A on sio1 at boot time, but > I receive buffer overruns when trying to use /dev/cuaa1 or /dev/ttyd1? What buffer overruns? interrupt-level, or tty-level? The first means your machine cannot cope with the interrupt rate, and finally the receiver shift buffer drops characters. That's a bit unlikely for a 16550A. The latter means the upper layers of the kernel are too slow to drain the data from the tty buffers the interrupt handler has been filling. This looks like your machine might be too slow to process the data, although there's some tuneable parameter where you could increase the tty-level buffer space. (I forgot which one however.) Naturally, if your application doesn't process all incoming data on average, you will always experience some form of buffer overflow, regardless of the buffer size. -- cheers, J"org joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE Never trust an operating system you don't have sources for. ;-)