Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262074AbTIHIca (ORCPT ); Mon, 8 Sep 2003 04:32:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262084AbTIHIca (ORCPT ); Mon, 8 Sep 2003 04:32:30 -0400 Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:55908 "EHLO ebiederm.dsl.xmission.com") by vger.kernel.org with ESMTP id S262086AbTIHIc2 (ORCPT ); Mon, 8 Sep 2003 04:32:28 -0400 To: Larry McVoy Cc: Stephen Satchell , "Martin J. Bligh" , William Lee Irwin III , Alan Cox , "Brown, Len" , Giuliano Pochini , Linux Kernel Mailing List Subject: Re: Scaling noise References: <105370000.1062622139@flay> <20030903212119.GX4306@holomorphy.com> <115070000.1062624541@flay> <20030903215135.GY4306@holomorphy.com> <116940000.1062625566@flay> <20030904010653.GD5227@work.bitmover.com> <20030907230729.GA19380@work.bitmover.com> <5.2.1.1.0.20030907214214.01c25ac8@fluent2.pyramid.net> <20030908052524.GA1990@work.bitmover.com> From: ebiederm@xmission.com (Eric W. Biederman) Date: 08 Sep 2003 02:32:03 -0600 In-Reply-To: <20030908052524.GA1990@work.bitmover.com> Message-ID: User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.2 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2980 Lines: 59 Larry McVoy writes: > On Sun, Sep 07, 2003 at 09:47:58PM -0700, Stephen Satchell wrote: > > At 05:57 PM 9/7/2003 -0700, Larry McVoy wrote: > > >That's not "a machine" that's ~1150 machines on a network. This business > > >of describing a bunch of boxes on a network as "a machine" is nonsense. > > > > Then you haven't been keeping up with Open-source projects, or the > > literature. > > Err, I'm in that literature, dig a little, you'll find me. I'm quite > familiar with clustering technology. While it is great that people are > wiring up lots of machines and running MPI or whatever on them, they've > been doing that for decades. It's only a recent thing that they started > calling that "a machine". That's marketing, and it's fine marketing, > but a bunch of machines, a network, and a library does not a machine make. Oh so you need cache coherency to make it a machine. That being the only difference between that and a NUMA box. Although I will state that there is a lot more that goes into such a system than a network, and a library. At least there is a lot more that goes into the manageable version of one. > Not to me it doesn't. I want to be able to exec a proces and have it land > anywhere on the "machine", any CPU, I want controlling tty semantics, > if I have 2300 processes in one process group then when I hit ^Z they > had all better stop. Etc. Oh wait none of that comes with cache coherency. So the difference cannot be cache coherency. > A collection of machines that work together is called a network of > machines, it's not one machine, it's a bunch of them. There's nothing > wrong with getting a lot of use out of a pile of networked machines, > it's a great thing. But it's no more a machine than the internet is > a machine. Cool so the SGI Ultrix is not a machine. Nor is the SMP box over in my lab. They are separate machines wired together with a network, and so I better start calling them a network of machines. As far as I can tell which pile of hardware to call a machine is a difference that makes no difference. Marketing as you put it. The only practical difference would seem to be what kind of problems you think are worth solving for a collection of hardware. By calling it a single machine I am saying I think it is worth solving the single system image problem. By refusing to call it a machine you seem to think it is a class of hardware which is not worth paying attention to. I do think it is a class of hardware that is worth solving the hard problems for. And I will continue to call that pile of hardware a machine until I give up on that. I admit the hard problems have not yet been solved but the solutions are coming. Eric - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/