From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: tuhs-bounces@minnie.tuhs.org X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_NONE autolearn=ham autolearn_force=no version=3.4.1 Received: from minnie.tuhs.org (minnie.tuhs.org [45.79.103.53]) by inbox.vuxu.org (OpenSMTPD) with ESMTP id 0e49617a for ; Wed, 27 Jun 2018 16:56:01 +0000 (UTC) Received: by minnie.tuhs.org (Postfix, from userid 112) id C1B20A188D; Thu, 28 Jun 2018 02:56:00 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id 3E7F9A1828; Thu, 28 Jun 2018 02:55:12 +1000 (AEST) Received: by minnie.tuhs.org (Postfix, from userid 112) id 1E1B99EDF1; Thu, 28 Jun 2018 02:55:08 +1000 (AEST) Received: from mail1.g22.pair.com (mail1.g22.pair.com [66.39.65.155]) by minnie.tuhs.org (Postfix) with ESMTPS id BE2D59EDF1 for ; Thu, 28 Jun 2018 02:55:07 +1000 (AEST) Received: from mail1.g22.pair.com (localhost [127.0.0.1]) by mail1.g22.pair.com (Postfix) with ESMTP id C8CF048498A; Wed, 27 Jun 2018 12:55:06 -0400 (EDT) Received: from [172.16.0.147] (unknown [88.98.95.237]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail1.g22.pair.com (Postfix) with ESMTPSA id 7D7214495C3; Wed, 27 Jun 2018 12:55:06 -0400 (EDT) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 10.3 \(3273\)) From: Tim Bradshaw In-Reply-To: Date: Wed, 27 Jun 2018 17:55:04 +0100 Content-Transfer-Encoding: quoted-printable Message-Id: References: <1f8043fd-e8d6-a5e6-5849-022d1a41f5bf@kilonet.net> <20180626215012.GE8150@mcvoy.com> To: Paul Winalski X-Mailer: Apple Mail (2.3273) Subject: Re: [TUHS] PDP-11 legacy, C, and modern architectures X-BeenThere: tuhs@minnie.tuhs.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: The Unix Heritage Society mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: TUHS main list Errors-To: tuhs-bounces@minnie.tuhs.org Sender: "TUHS" On 27 Jun 2018, at 16:30, Paul Winalski wrote: >=20 > What Clem said. Chisnall is right about C having been designed for a > sequential-programming world. That's why Fortran (with array and > other parallel/vector operations built in) rules in the HPTC parallel > programming space. But I don't buy most of his arguments. Making > parallel programming easy and natural has been an unsolved problem > during my entire 30+ year career in designing software development > tools. It's still an unsolved problem. [...] I think that's right. The missing bit is that while once the only = people who had to worry about processors with a lot of parallelism were = the HPC people, who fortunately often had algorithms which parallelised = rather well. Now you have to worry about it if you want to write = programs for the processor in your laptop and probably the processor in = your watch. Or you would, if the designers of those processors had not = gone to heroic lengths to make them look like giant PDP-11s. = Unfortunately those heroic lengths haven't been heroic enough as has = become apparent, and will presumably fall apart increasingly rapidly = from now on. So he's right: the giant PDP-11 thing is a disaster, but he's wrong = about its cause: it's not caused by C, but by the fact that writing = programs for what systems really need to look like is just an unsolved = problem. It might have helped if we had not spent forty years sweeping = it busily under the carpet. A thing that is also coming of course, which he does not talk about, is = that big parallel machines are also going to start getting increasingly = constrained by physics which means that a lot of the tricks that HPC = people use will start to fall apart as well.