From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rob Landley Subject: Re: [Lhms-devel] [PATCH 0/7] Fragmentation Avoidance V19 Date: Wed, 2 Nov 2005 18:10:27 -0600 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: owner-linux-mm@kvack.org Return-Path: To: Gerrit Huizenga 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 List-ID: 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org