From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=5.0 tests=MAILING_LIST_MULTI, RCVD_IN_DNSWL_NONE autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 17226 invoked from network); 21 Jul 2020 01:52:35 -0000 Received: from minnie.tuhs.org (45.79.103.53) by inbox.vuxu.org with ESMTPUTF8; 21 Jul 2020 01:52:35 -0000 Received: by minnie.tuhs.org (Postfix, from userid 112) id F40779BA4C; Tue, 21 Jul 2020 11:52:27 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id 7418B9BA30; Tue, 21 Jul 2020 11:51:03 +1000 (AEST) Received: by minnie.tuhs.org (Postfix, from userid 112) id 1B19D9BA30; Tue, 21 Jul 2020 11:50:59 +1000 (AEST) Received: from mcvoy.com (mcvoy.com [192.169.23.250]) by minnie.tuhs.org (Postfix) with ESMTPS id 044669BA2A for ; Tue, 21 Jul 2020 11:50:58 +1000 (AEST) Received: by mcvoy.com (Postfix, from userid 3546) id BB8E235E14D; Mon, 20 Jul 2020 18:50:57 -0700 (PDT) Date: Mon, 20 Jul 2020 18:50:57 -0700 From: Larry McVoy To: Andrew Warkentin Message-ID: <20200721015057.GV26294@mcvoy.com> References: <2135afdb-db52-05d2-9af6-24ad36367db3@tnetconsulting.net> <40a70393-894a-4b21-8678-a71bbca4aa69@localhost> <8e7efd45-a84e-cf20-9d30-8222357596a3@tnetconsulting.net> <202007200847.06K8l8DF026646@freefriends.org> <6528890D-947F-4393-8578-5B797AF6FF8E@doomd.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) Subject: Re: [TUHS] A/UX [was Linux is on-topic] X-BeenThere: tuhs@minnie.tuhs.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: The Unix Heritage Society mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: tuhs@tuhs.org Errors-To: tuhs-bounces@minnie.tuhs.org Sender: "TUHS" On Mon, Jul 20, 2020 at 06:54:40AM -0600, Andrew Warkentin wrote: > On 7/20/20, Larry McVoy wrote: > > This isn't quite the same but Victor Yodaiken wrote a real time kernel > > that ran all of Linux as a user process. Super cool idea and it worked > > great, he would demo it sampling the parallel port while Linux was running > > some X11 perf thing, tarring up /usr and untarring on nfs://server/tmp/usr > > and doing a ftp transfer. Basically beating the crap out of Linux as > > hard as he could while running a real time sampler and it never missed. > > > > Clem should pay attention, in my opinion, this is how you do Unix and > > real time. Because Unix is time sharing and throughput, that is the > > opposite of what real time is. Wedging real time into Unix is a mistake. > > > > QNX manages to do realtime fairly decently while still being > Unix-like, although it's certainly not a conventional Unix. With a > multi-server OS with a properly designed microkernel, it is possible > for realtime threads to more or less ignore the fact that they're > running on a Unix-like OS (provided that they can access some kind of > IPC API that closely matches that of the kernel) since all the OS > services other than the microkernel are running beside them at > non-realtime priorities, and not underneath them as in a conventional > OS. It's kind of doing the same thing as running a Unix kernel as a > process under a realtime kernel, but the Unix environment is > implemented by servers and libraries instead of a monolithic kernel. QNX is awesome. I was friends with Dan Hildebrandt, he was one of the 3 people who were allowed to touch the microkernel code. That kernel could fit easily in a 4K instruction cache and leave room for other processes. They measured everything in cache misses, every commit had them thinking about cache misses. I'm definitely a unikernel guy but I had mad respect for QNX, Dan and I would talk often about stuff, like how would this work in your world and how would it work in my world. The QNX core team was amazing. Sadly, we lost Dan to brain cancer (I think) in 1998. -- --- Larry McVoy lm at mcvoy.com http://www.mcvoy.com/lm