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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