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 0b7f8528 for ; Thu, 28 Jun 2018 15:40:15 +0000 (UTC) Received: by minnie.tuhs.org (Postfix, from userid 112) id C42FB9EDF1; Fri, 29 Jun 2018 01:40:14 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id 4F050A1816; Fri, 29 Jun 2018 01:40:04 +1000 (AEST) Received: by minnie.tuhs.org (Postfix, from userid 112) id C29DD9EDF1; Fri, 29 Jun 2018 01:40:02 +1000 (AEST) Received: from mail1.g22.pair.com (mail1.g22.pair.com [66.39.65.155]) by minnie.tuhs.org (Postfix) with ESMTPS id 56DF19EDF1 for ; Fri, 29 Jun 2018 01:40:02 +1000 (AEST) Received: from mail1.g22.pair.com (localhost [127.0.0.1]) by mail1.g22.pair.com (Postfix) with ESMTP id 63A864849E6; Thu, 28 Jun 2018 11:40:01 -0400 (EDT) Received: from [172.16.0.145] (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 3967844945E; Thu, 28 Jun 2018 11:40:01 -0400 (EDT) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (1.0) From: Tim Bradshaw X-Mailer: iPhone Mail (15F79) In-Reply-To: <20180628145825.GE21688@mcvoy.com> Date: Thu, 28 Jun 2018 16:39:58 +0100 Content-Transfer-Encoding: quoted-printable Message-Id: <2B710879-7659-47A4-AA86-03F232F7B78B@tfeb.org> References: <81277CC3-3C4A-49B8-8720-CFAD22BB28F8@bitblocks.com> <20180628141538.GB663@thunk.org> <20180628144017.GB21688@mcvoy.com> <20180628105538.65f82615@jabberwock.cb.piermont.com> <20180628145825.GE21688@mcvoy.com> To: Larry McVoy 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@minnie.tuhs.org Errors-To: tuhs-bounces@minnie.tuhs.org Sender: "TUHS" > On 28 Jun 2018, at 15:58, Larry McVoy wrote: >=20 > You completely missed my point, I never said I was in favor of single > cpu systems, I said I the speed of a single cpu to be fast no matter > how many of them I get. The opposite of wimpy. And this also misses the point, I think. Defining a core as 'wimpy' or not i= s dependent on when you make the definition: the Cray-1 was not wimpy when i= t was built, but it is now. The interesting question is what happens to the= performance of serial code on a core over time. For a long time it has inc= reased, famously, approximately exponentially. There is good evidence that t= his is no longer the case and that per-core performance will fall off (or ha= s fallen off in fact) that curve and may even become asymptotically constant= . If that's true, then in due course *all cores will become 'wimpy'*, and t= o exploit the performance available from systems we will *have* to deal with= parallelism. (Note I've said 'core' not 'CPU' for clarity even when it's anachronistic: I= never know what the right terminology is now.)=