From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264270AbTDOFhX (for ); Tue, 15 Apr 2003 01:37:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264299AbTDOFhX (for ); Tue, 15 Apr 2003 01:37:23 -0400 Received: from franka.aracnet.com ([216.99.193.44]:27114 "EHLO franka.aracnet.com") by vger.kernel.org with ESMTP id S264270AbTDOFhW (for ); Tue, 15 Apr 2003 01:37:22 -0400 Date: Mon, 14 Apr 2003 22:49:03 -0700 From: "Martin J. Bligh" To: Antonio Vargas cc: linux-kernel@vger.kernel.org, nicoya@apia.dhs.org Subject: Re: cow-ahead N pages for fault clustering Message-ID: <20890000.1050385742@[10.10.2.4]> In-Reply-To: <20030414184715.GI14552@wind.cocodriloo.com> References: <10760000.1050332136@[10.10.2.4]> <20030414152947.GB14552@wind.cocodriloo.com> <12790000.1050334744@[10.10.2.4]> <20030414155748.GD14552@wind.cocodriloo.com> <14860000.1050337484@[10.10.2.4]> <20030414164321.GE14552@wind.cocodriloo.com> <15700000.1050338226@[10.10.2.4]> <20030414171419.GG14552@wind.cocodriloo.com> <16700000.1050340965@[10.10.2.4]> <20030414183251.GH14552@wind.cocodriloo.com> <20030414184715.GI14552@wind.cocodriloo.com> X-Mailer: Mulberry/2.2.1 (Linux/x86) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org >> > >> Ah, you probably don't want to do that ... it's very expensive. >> > >> Moreover, if you exec 2ns later, all the effort will be wasted ... >> > >> and it's very hard to deterministically predict whether you'll exec >> > >> or not (stupid UNIX semantics). Doing it lazily is probably best, >> > >> and as to "nodes would not have to reference the memory from >> > >> others" - you're still doing that, you're just batching it on the >> > >> front end. >> > > >> > > True... What about a vma-level COW-ahead just like we have a >> > > file-level read-ahead, then? I mean batching the COW at >> > > unCOW-because-of-write time. >> > >> > That'd be interesting ... and you can test that on a UP box, is not >> > just NUMA. Depends on the workload quite heavily, I suspect. >> > >> > > btw, COW-ahead sound really silly :) >> > >> > Yeah. So be sure to call it that if it works out ... we need more >> > things like that ;-) Moooooo. >> >> What about the attached one? I'm compiling it right now to test in UML :) >> >> [ snip fake-NUMA-on-SMP discussion ] >> > > OK, too quick for me... this next one applies, compiles and boots on > 2.5.66 + uml. Now I wonder how can I test if this is useful... ideas? Well, benchmark it ;-) My favourite trick is to just "/usr/bin/time make bzImage" on some fixed kernel version & config, but aim7 / aim9 is pretty easy to set up too, and might be interesting. M.