Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030261AbVKCBhg (ORCPT ); Wed, 2 Nov 2005 20:37:36 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030258AbVKCBhf (ORCPT ); Wed, 2 Nov 2005 20:37:35 -0500 Received: from dsl092-053-140.phl1.dsl.speakeasy.net ([66.92.53.140]:2188 "EHLO grelber.thyrsus.com") by vger.kernel.org with ESMTP id S1030261AbVKCBhc (ORCPT ); Wed, 2 Nov 2005 20:37:32 -0500 From: Rob Landley Organization: Boundaries Unlimited To: Gerrit Huizenga Subject: Re: [Lhms-devel] [PATCH 0/7] Fragmentation Avoidance V19 Date: Wed, 2 Nov 2005 18:10:27 -0600 User-Agent: KMail/1.8 Cc: Ingo Molnar , Kamezawa Hiroyuki , Dave Hansen , Mel Gorman , Nick Piggin , "Martin J. Bligh" , Andrew Morton , kravetz@us.ibm.com, linux-mm , Linux Kernel Mailing List , lhms References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200511021810.28948.rob@landley.net> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1332 Lines: 26 On Wednesday 02 November 2005 09:02, Gerrit Huizenga wrote: > > but that's obviously not 'generic unpluggable kernel RAM'. It's very > > special RAM: RAM that is free or easily freeable. I never argued that > > such RAM is not returnable to the hypervisor. > > Okay - and 'generic unpluggable kernel RAM' has not been a goal for > the hypervisor based environments. I believe it is closer to being > a goal for those machines which want to hot-remove DIMMs or physical > memory, e.g. those with IA64 machines wishing to remove entire nodes Keep in mind that just about any virtualized environment might benefit from being able to tell the parent system "we're not using this ram". I mentioned UML, and I can also imagine a Linux driver that signals qemu (or even vmware) to say "this chunk of physical memory isn't currently in use", and even if they don't actually _free_ it they can call madvise() on it. Heck, if we have prezeroing of large blocks, telling your emulator to madvise(ADV_DONTNEED) the pages for you should just plug right in to that infrastructure... Rob - 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/