From owner-freebsd-hardware Thu Jul 4 01:51:20 1996 Return-Path: owner-hardware Received: (from root@localhost) by freefall.freebsd.org (8.7.5/8.7.3) id BAA13108 for hardware-outgoing; Thu, 4 Jul 1996 01:51:20 -0700 (PDT) Received: from uu.elvisti.kiev.ua (acc0.elvisti.kiev.ua [193.125.28.132]) by freefall.freebsd.org (8.7.5/8.7.3) with ESMTP id BAA12507; Thu, 4 Jul 1996 01:43:34 -0700 (PDT) Received: from office.elvisti.kiev.ua (office.elvisti.kiev.ua [193.125.28.129]) by uu.elvisti.kiev.ua (8.7.5/8.7.3) with ESMTP id MAA25714; Thu, 4 Jul 1996 12:04:31 +0300 (EET DST) Received: (from stesin@localhost) by office.elvisti.kiev.ua (8.6.12/8.ElVisti) id MAA23321; Thu, 4 Jul 1996 12:04:30 +0300 From: "Andrew V. Stesin" Message-Id: <199607040904.MAA23321@office.elvisti.kiev.ua> Subject: Re: muliport boards - building a PPP dialup server To: bde@zeta.org.au (Bruce Evans) Date: Thu, 4 Jul 1996 12:04:30 +0300 (EET DST) Cc: hardware@freebsd.org, isp@freebsd.org In-Reply-To: <199607032027.GAA15101@godzilla.zeta.org.au> from "Bruce Evans" at Jul 4, 96 06:27:05 am X-Mailer: ELM [version 2.4 PL24alpha5] Content-Type: text Sender: owner-hardware@freebsd.org X-Loop: FreeBSD.org Precedence: bulk [... Cc: trimmed ...] Thanks alot for the explanation, Bruce! # source overhead relative # ------ # serial interrupt overheads 3% per 11KB 1 # system overheads for termios raw mode input 3.3 1 # system overheads for cslip input 3.7 1+ # system overheads for pppd input 6.1 2 # system overheads for termios cooked mode input huge (50?) 16 # # The system overheads are easy to reduce by replacing the 486/33 with a # Pentium. The interrupt overheads are mostly I/O overheads so they are # hard to reduce because boards with fast I/O are hard to find. So an idea to get a PCI board seems to be pretty reasonable... # > 2. ISA bus itself, no matter what will I put into it. # # This is the main bottleneck on anything faster than a DX2/66, at least # if 8-bit I/O is used. The overheads for Comtrol RocketPorts would be # about half as small because RocketPorts support 16-bit I/O. Anyway, ISA is a dead-end, I think. (Consider the following: 16 ports seems to be an upper limit for ISA card at 8MHz, even if it's 16bit "smart" one -- simply because it's ISA. PCI has 33Mhz => 4 times faster, it's a 32bit bus => add two times more. So PCI intellgent card should be able to handle at least 8 times more ports at full speed, => up to 128 ones! And just today I have a headache -- we already have 16 ports busy on a dialup server, what will I do when some 2 more lines will come? Seems that getting a smart PCI serial device is the easiest solution and a more reasonable investment than a second server, considering added complexity of distributed system). # Bruce # -- 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.