Date: Wed, 3 Jul 1996 17:57:03 +0300 (EET DST) From: "Andrew V. Stesin" <stesin@elvisti.kiev.ua> To: msmith@atrad.adelaide.edu.au (Michael Smith) Cc: hardware@freebsd.org Subject: Re: muliport boards - building a PPP dialup server Message-ID: <199607031457.RAA04815@office.elvisti.kiev.ua> In-Reply-To: <199607031402.XAA09755@genesis.atrad.adelaide.edu.au> from "Michael Smith" at Jul 3, 96 11:32:51 pm
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# Sales people are universally useless. I almost always try to make # contact with technical staff when evaluating a product. That's life... I wasn't lucky enough to get a person's name from them, -- but I was dumb enough to forget that I can look at copyright notice in the driver :-) # > 1. tty-level driver overhead, that's what I'm watching # > now with 16 FIFOed ports in 486dx4/100 -- interrupt # > load is tiny, and most of CPU is eaten by system. # > "Smart" card with it's own CPU (I treat it like # > an I/O co-processor) should minimize this factor. (?) # # No. None of the 'smart' cards currently around perform any tty processing. Won't tty-level overhead decrease when the data flow through a port will be going in bigger chunks? # > 2. ISA bus itself, no matter what will I put into it. # > We don't have any EISA slots; so PCI is left. # > (And should I mention the fact that there are boxes around # > of non-Intel architectures running unices, which # > have PCI slots but no ISA slots?) Yes, probably I'm # > wrong and ISA can deal i.e. with 32x115200; but how # > reliable will this configuration be? # # This is a significant issue. 32x115200 is ~350K/sec. presuming 100% # efficiency. IIRC, Bruce quoted more like 50%, so the ISA bus would be # prettymuch saturated. A 'smart' card with a shared-memory interface # might be more efficient in this case. That's precisely what I meant. Pentium won't help here :-) About shared-memory interface -- doesn't it work through the same ISA bus, anyway? Yes, it will decrease interrupt load, but won't it keep ISA bus busy -- this way or another? -- With best regards -- Andrew Stesin. Phones/fax: +380 (44) { 244-0122, 276-0188, 271-3457, 271-3560 } "You may delegate authority, but not responsibility." Frank's Management Rule #1.
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