From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,fd0ee7c9be011576 X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2001-03-06 10:44:05 PST Path: supernews.google.com!sn-xit-03!supernews.com!freenix!oleane.net!oleane!fr.clara.net!heighliner.fr.clara.net!grolier!dispose.news.demon.net!demon!diablo.dera.gov.uk!dera!not-for-mail From: "Kevin Rigotti" Newsgroups: comp.lang.ada Subject: Re: Ada Annex E (Just curious :-) Date: Tue, 6 Mar 2001 18:42:01 -0000 Organization: Defence Evaluation & Research Agency Message-ID: <983b1s$m6h$1@trog.dera.gov.uk> References: <3AA29386.E60A686D@linuxchip.demon.co.uk> <980ekl$p4h$1@nh.pace.co.uk> <3AA43C58.105B970D@linuxchip.demon.co.uk> <982veb$l62$1@nh.pace.co.uk> NNTP-Posting-Host: 194.61.191.135 X-Newsreader: Microsoft Outlook Express 4.72.3612.1700 X-MimeOLE: Produced By Microsoft MimeOLE V4.72.3612.1700 Xref: supernews.google.com comp.lang.ada:5474 Date: 2001-03-06T18:42:01+00:00 List-Id: Marin David Condic wrote in message <982veb$l62$1@nh.pace.co.uk>... >Obviously, there is more than one way to skin this cat, but having glanced >at the rationale for Annex E, I can see how it was intended to be used and >could be fairly handy for some systems with shared resources. I think that a >big drawback would be that to use it in a system that didn't have a nice, >common architecture & RTK/RTOS, you'd have to get your compiler >custom-modified for the hardware you had. I'm speaking from a position of ignorance, having never done it, but perhaps BSP (http://www.bsp-worldwide.org/) style distributed processing would be useful? Namely, all non-local read and write requests queued locally until the end of the super-step, then completed by message passing using "Annex E mechanisms". There would be no need for that to be homogenous. If one partition were set up as controller, and each of the others registered themselves with it on startup then it would be easy enough to give everything a vector of access values for remote dispatching to the other components. What you *do* need for any BSP-like thing is an efficient way of doing multicast messaging and n-way rendezvous. I'm not at all clear on how to do that efficiently in Ada. If the application had sufficiently many natural synchronisation points then deferring the communication wouldn't be too expensive, and performance would at least be predictable if not actually scalable. Maybe? It's something I've wanted to play with but never had the time or funding for :-) Kevin -- ATC Systems Group, DERA, St Andrews Road, Malvern, Worcestershire WR14 3PS, UK Phone +44 (0)1684 89 69 11, fax +44(0)1684 89 41 09 DERA disclaimers and restrictions apply, details on request