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-Thread: 103376,b95a522100671708 X-Google-Attributes: gid103376,public X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news1.google.com!news4.google.com!news.glorb.com!meganewsservers.com!feeder2.on.meganewsservers.com!feed.cgocable.net!read1.cgocable.net.POSTED!53ab2750!not-for-mail From: "Warren W. Gay VE3WWG" User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.7.2) Gecko/20040804 Netscape/7.2 (ax) X-Accept-Language: en-us, en MIME-Version: 1.0 Newsgroups: comp.lang.ada Subject: Re: For the AdaOS folks References: <1PTAd.1218$0y4.421@read1.cgocable.net> In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Message-ID: Date: Wed, 05 Jan 2005 21:34:24 -0500 NNTP-Posting-Host: 24.150.168.167 X-Complaints-To: abuse@cogeco.ca X-Trace: read1.cgocable.net 1104978867 24.150.168.167 (Wed, 05 Jan 2005 21:34:27 EST) NNTP-Posting-Date: Wed, 05 Jan 2005 21:34:27 EST Organization: Cogeco Cable Xref: g2news1.google.com comp.lang.ada:7510 Date: 2005-01-05T21:34:24-05:00 List-Id: Nick Roberts wrote: > "Warren W. Gay VE3WWG" wrote: >>Mach's roots go back to 1975, which is quite some time ago ;-) > > Blimey, I didn't know that. I started designing the microkernel that has > become Bachar in the mid 1980s. Certainly I had never heard of Mach at that > time. There is a little Mach history blurb available at: http://hurd.gnufans.org/bin/view/Mach/MachHistory Presumably if the project started in 1975, the ideas must have been floating around for a time prior to that. >>However, the "name service" for example, will often have many clients >>(only one receive port for the name service, but at least one send-right >>for every client "task" on the system). This is one example where the >>numbers of send-rights can be large. ... > Looking at my Windows XP Task Manager just now, I see 47 processes and 446 > threads. Interesting. I'm not sure if it's a problem. Currently, I > anticipate capacity for 500 processes and 1500 threads (per workstation), > and for 1000 IPC services and 3000 service keys. Each (normal) thread will > eat up about 300 bytes of RAM (for the TSS and ring 0, 1, and 2 stacks). The > RAM used up for an IPC service or service key is negligible. > > How would Mach do it better? The only suggestion I was making is that if you separate the port from the thread (the "Mach way" instead of the L4 way where port=thread), then you don't have the "thread memory overhead" for each "port". A port becomes much like a UNIX file descriptor, where a dup(2)-ed file descriptor just shares an existing file entry (virtually no overhead - just a pointer and reference count). A port just becomes a nearly cost-free handle. As soon as you say every communication end-point implies a thread, then I as a designer, have to start counting the cost. -- Warren W. Gay VE3WWG http://home.cogeco.ca/~ve3wwg