Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932632AbWAJVA7 (ORCPT ); Tue, 10 Jan 2006 16:00:59 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932629AbWAJVA7 (ORCPT ); Tue, 10 Jan 2006 16:00:59 -0500 Received: from ns.virtualhost.dk ([195.184.98.160]:36178 "EHLO virtualhost.dk") by vger.kernel.org with ESMTP id S932632AbWAJVA6 (ORCPT ); Tue, 10 Jan 2006 16:00:58 -0500 Date: Tue, 10 Jan 2006 22:02:37 +0100 From: Jens Axboe To: "Jeff V. Merkey" Cc: Alan Cox , Linus Torvalds , Martin Bligh , Byron Stanoszek , Ingo Molnar , linux-kernel@vger.kernel.org, Andrew Morton Subject: Re: 2G memory split Message-ID: <20060110210237.GL3389@suse.de> References: <20060110132957.GA28666@elte.hu> <20060110133728.GB3389@suse.de> <20060110143931.GM3389@suse.de> <43C3F986.4090209@mbligh.org> <43C3E74D.7060309@wolfmountaingroup.com> <1136926519.14532.46.camel@localhost.localdomain> <43C40738.4070600@wolfmountaingroup.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <43C40738.4070600@wolfmountaingroup.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1466 Lines: 43 On Tue, Jan 10 2006, Jeff V. Merkey wrote: > Alan Cox wrote: > > >On Maw, 2006-01-10 at 09:56 -0700, Jeff V. Merkey wrote: > > > > > >>RH ES uses 4:4 which is ideal and superior to this hack. > >> > >> > > > >Its a non trivial trade-off. 4/4 lets you run very large physical memory > >systems much more efficiently than usual but you pay a cost on syscalls > >and some other events when using the majority of processors. The 4/4 > >tricks also give most emulations (eg Qemu) serious heartburn trying to > >emulate %cr3 reloading via mmap and other interfaces with high overhead > >in relative terms. > > > >Of course AMD64 kind of shot the problem in the head once and for all. > > > > > > > > Yep, they sure did. Seriously, the 4:4 option should also be present > along with 3:1 and 2:2 > splits. You should merge your RH work into this patch and allow both. > It would save me one less > patch to maintain off the tree. You can't compare the two patches, saying that 4:4 should go in because configurable page offsets is merged is nonsense. Note that I'm not advocating against 4:4 as such, I have no real oppinion on that. It has its uses for sure, while it comes with a cost for others. -- Jens Axboe - 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/