Date: Fri, 5 Apr 1996 12:40:51 -0600 (CST) From: Joe Greco <jgreco@brasil.moneng.mei.com> To: bde@zeta.org.au (Bruce Evans) Cc: bde@zeta.org.au, jgreco@brasil.moneng.mei.com, current@FreeBSD.ORG, root@deadline.snafu.de Subject: Re: tty-level buffer overflows - what to do? Message-ID: <199604051840.MAA05100@brasil.moneng.mei.com> In-Reply-To: <199604051826.EAA18166@godzilla.zeta.org.au> from "Bruce Evans" at Apr 6, 96 04:26:33 am
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> >> >What kind of drives? IDE drives bite, particularly if they are being used > >> >at the same time as the serial port... etc, etc. > >> > >> IDE drives have no affect on the operation of the serial unless they > >> are so slow that the system spends too much of its time in the kernel. > >> Bus-hogging SCSI controllers bite. > > >It has been my observation that IDE drives DO tend to affect the operation > >of serial I/O, at least during heavy I/O periods. Small-memory systems tend > >to spend much more time doing "heavy I/O" (swapping), in my experience, this > >is just one reason I put 8MB in even my smallest machines these days. > > It's an indirect effect. Small-memory systems are more likely to have > slow IDE drives that make the swapping slower. You probably can't > afford to swap the applications doing serial i/o at all if you don't use > flow control - the kernel buffers are only large enough for 100 msec of > input at 115200 bps. Well, even with drives like the WDC Caviar's (the most common IDE drive around here)... and with flow control... you can see some lossage. _My_ recommendation is to build the systems so you don't use the disk much. And it works for me. :-) YMMV ... Joe ------------------------------------------------------------------------------- Joe Greco - Systems Administrator jgreco@ns.sol.net Solaria Public Access UNIX - Milwaukee, WI 414/546-7968
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