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Xref: sserve comp.os.linux.development:18485 comp.os.linux.misc:28575 comp.os.386bsd.questions:14160 comp.os.386bsd.misc:3908 sci.electronics:83040 Path: sserve!newshost.anu.edu.au!harbinger.cc.monash.edu.au!msuinfo!uwm.edu!news.alpha.net!news.mathworks.com!europa.eng.gtefsd.com!newsxfer.itd.umich.edu!gumby!andrews-cc!gillham From: gillham@andrews.edu (Andrew Gillham) Newsgroups: comp.os.linux.development,comp.os.linux.misc,comp.os.386bsd.questions,comp.os.386bsd.misc,sci.electronics Subject: Re: 16550 detection Date: 2 Nov 1994 01:33:06 GMT Organization: Andrews University Lines: 35 Message-ID: <396q8i$fap@orion.cc.andrews.edu> References: <CMETZ.94Oct30051603@itchy.inner.net> <TYTSO.94Oct31162517@dcl.mit.edu> <MICHAELV.94Oct31211019@MindBender.HeadCandy.com> <TYTSO.94Nov1182557@dcl.mit.edu> NNTP-Posting-Host: edmund.cs.andrews.edu In article <TYTSO.94Nov1182557@dcl.mit.edu> tytso@athena.mit.edu (Theodore Y. Ts'o) writes: [stuff that almost sounded like Hayes bashing.. :-) ] > > - Ted > >P.S. That's not to say that a larger FIFO buffer wouldn't be helpful to >avoid problems. If you have some interrupt latency problems, and a >super fast modem, and a slow CPU, the larger FIFO is undoubtedly useful. >But that presupposes other problems in your operating system, either >software or hardware, to begin with. On many systems, the 1024 byte >FIFO is just loafing... Not to sound stupid, but why does everybody refer to "interrupt latency" and CPU/MODEM speed and make it sound like they're only talking about *ONE* serial port? Seems to me that if you have 8 ports and want to run them all at 115200, then you damn well better have a larger FIFO! I don't know what the interrupt latency numbers look like for NetBSD or Linux, but I don't imagine the serial port performance is very scalable with plain old NS16550A's? 1 port at 115kbps should be easy, but what about 2, 4, 8, 16? I'd take the 1024 byte fifo any day! Especially if I could program the board with separate trigger levels for different ports. i.e. 10 byte trigger for an interactive terminal, but maybe a 256 byte trigger on a "non-interactive" device. On a side note, does anybodyng a multi-port serial card want to comment on performance with 2-4+ serial ports going full blast? -Andrew -- ========================================================== Andrew Gillham gillham@andrews.edu LAN/WAN/Netware/Unix Analyst gillham@whirlpool.com ==========================================================