From mboxrd@z Thu Jan 1 00:00:00 1970 From: Johannes Weiner Subject: Re: [PATCH 0/3] bootmem2 III References: <20080509151713.939253437@saeurebad.de> <20080509184044.GA19109@one.firstfloor.org> <87lk2gtzta.fsf@saeurebad.de> <48275493.40601@firstfloor.org> <874p92qsvn.fsf@saeurebad.de> <482990AB.7070905@firstfloor.org> Date: Wed, 14 May 2008 21:12:47 +0200 In-Reply-To: <482990AB.7070905@firstfloor.org> (Andi Kleen's message of "Tue, 13 May 2008 14:59:23 +0200") Message-ID: <87ve1gpumo.fsf@saeurebad.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-linux-mm@kvack.org Return-Path: To: Andi Kleen Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Ingo Molnar , Yinghai Lu , Andrew Morton , Linus Torvalds List-ID: Hi Andi, Andi Kleen writes: >> I was wondering yesterday if it would be feasible to enforce >> contiguousness for nodes. > > And lose the memory? That would make people not happy. No, one node descriptor per contiguous block on the physical node. So this setup: node 0: 0-2G, 4-6G node 1: 2-4G, 6-8G would have 4 pgdats. >> So that arch-code does not create one pgdat >> for each node but one for each contiguous block. I have not yet looked >> deeper into it, but I suspect that other mm code has similar problems >> with nodes spanning other nodes. > > I wouldn't think so. At least sparse memory with large holes is not that > uncommon in the non x86 world. I do not quite understand. Holes are not the problem - the overlapping is. The current bootmem allocator for example might pass the same pfn twice to the buddy allocator when two nodes overlap. And I don't know if other mm code has the same problem. Hannes -- 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