Date: Thu, 12 Feb 1998 23:06:22 +0000 (GMT) From: Terry Lambert <tlambert@primenet.com> To: eivind@yes.no (Eivind Eklund) Cc: wollman@khavrinen.lcs.mit.edu, eivind@yes.no, current@FreeBSD.ORG Subject: Re: Heads up: static -ification Message-ID: <199802122306.QAA04054@usr02.primenet.com> In-Reply-To: <19980212161814.38690@follo.net> from "Eivind Eklund" at Feb 12, 98 04:18:14 pm
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> > ``Layering is a great model for designing protocols, but an incredibly > > lousy way of implementing them.'' > > - D. D. Clark > > That quote is often true for protocols, yes. OTOH, I haven't yet > found a way of implementing advanced protocols that isn't lousy. Have you ever heard of a "monostack"? In a traditional streams implementation, given when streams runs, a protocol stack will not run to completion pushing message either up or down (or if they are badly arranged, both directions). A "monostack" overcomes this problem by creating a monolithic protocol, per traditional designs, and then exporting discrete protocol components. For instance, I might have a monostack that implements IP, ICMP, UDP, and TCP, and exports each of these interfaces as if they were segregable, when in fact they were not. Because of this, an inbound or outbound TCP packet can run to completion through the stack without incurring a streams scheduling overhead from the processing order not matching the stacking order. > At least for operating systems, message-passing systems tend to be > beautifully simple. The main problem is that if you do them in a > memory-protected environment your performance tend to suck. And you can't get orangebook certification using statistical memory protections. ;-). Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe current" in the body of the message
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