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=-0.6 required=5.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_NONE, T_DKIM_INVALID 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 a36b9c89 for ; Thu, 28 Jun 2018 22:30:13 +0000 (UTC) Received: by minnie.tuhs.org (Postfix, from userid 112) id 975E7A1B0A; Fri, 29 Jun 2018 08:30:12 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id 30243A1857; Fri, 29 Jun 2018 08:29:59 +1000 (AEST) Authentication-Results: minnie.tuhs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=thunk.org header.i=@thunk.org header.b=uUWTMST2; dkim-atps=neutral Received: by minnie.tuhs.org (Postfix, from userid 112) id D489EA1857; Fri, 29 Jun 2018 08:29:57 +1000 (AEST) Received: from imap.thunk.org (imap.thunk.org [74.207.234.97]) by minnie.tuhs.org (Postfix) with ESMTPS id A4B7EA1815 for ; Fri, 29 Jun 2018 08:29:56 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=thunk.org; s=ef5046eb; h=In-Reply-To:Content-Type:MIME-Version:References:Message-ID: Subject:Cc:To:From:Date:Sender:Reply-To:Content-Transfer-Encoding:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=ygz/oOe3UiThQibDMowejJRyu0RexQCIjNia9uzTu5w=; b=uUWTMST2/LFi9xehLrgzL1yBqn gU/RcRPwVwt+aC0wdBU6/TPwxZNh6Vs3R5hYrM1oYFp0xAEHVpAmCDXCdkHLJlBpqs+W6g+caiJfW ElmK7vY87hoTY4BzY2W3e7dw3TFU7jvMlKvUMe1z34oLnZFTCkaUGvrRQ294cvqalVx0=; Received: from root (helo=callcc.thunk.org) by imap.thunk.org with local-esmtp (Exim 4.89) (envelope-from ) id 1fYfQJ-00030R-81; Thu, 28 Jun 2018 22:29:55 +0000 Received: by callcc.thunk.org (Postfix, from userid 15806) id 749537A4480; Thu, 28 Jun 2018 18:29:54 -0400 (EDT) Date: Thu, 28 Jun 2018 18:29:54 -0400 From: "Theodore Y. Ts'o" To: "Perry E. Metzger" Message-ID: <20180628222954.GD8521@thunk.org> References: <81277CC3-3C4A-49B8-8720-CFAD22BB28F8@bitblocks.com> <20180628141538.GB663@thunk.org> <20180628104329.754d2c19@jabberwock.cb.piermont.com> <20180628145609.GD21688@mcvoy.com> <20180628154246.3a1ce74a@jabberwock.cb.piermont.com> <20180628170317.14d65067@jabberwock.cb.piermont.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180628170317.14d65067@jabberwock.cb.piermont.com> User-Agent: Mutt/1.10.0 (2018-05-17) X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: tytso@thunk.org X-SA-Exim-Scanned: No (on imap.thunk.org); SAEximRunCond expanded to false 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 Thu, Jun 28, 2018 at 05:03:17PM -0400, Perry E. Metzger wrote: > > Tens of thousands of machines is a lot more than one. I think the > point stands. This is the age of distributed and parallel systems. This is the age of distributed systems, yes. I'm not so sure about "parallel". And the point remains that for many problems, you need fewer strong cores, and a crapton of weak cores is not as useful. Of course we should parllelize work where we can. The point is that very often, we can't. And if you are really worried about potential problems with Spectre and Meltdown, what that means is that sharing caches is perilous. So if you have 128 wimpy cores, you need 128 separate I and D cacaches. If you have 32 stronger cores, you need 32 separate I and D caches. And the fact remains that humans really suck at parallel programming. Use a separate core for each HTTP request, with a load balancer to split the incoming request to tens of hundreds servers? Sure! But using a several dozen cores for each HTTP request? That's a much bigger lift. You're conflating "distributed" and "parllel" computing, and they are really quite different. - Ted