From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 2 Apr 2007 10:34:38 -0700 (PDT) From: Christoph Lameter Subject: Re: [PATCH 1/4] x86_64: Switch to SPARSE_VIRTUAL In-Reply-To: <200704021914.07541.ak@suse.de> Message-ID: References: <20070401071024.23757.4113.sendpatchset@schroedinger.engr.sgi.com> <200704021744.39880.ak@suse.de> <200704021914.07541.ak@suse.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-arch@vger.kernel.org, Martin Bligh , linux-mm@kvack.org, KAMEZAWA Hiroyuki List-ID: On Mon, 2 Apr 2007, Andi Kleen wrote: > > No no no. For the gazillions time: All of 1-1 mapped kernel memory on > > x86_64 needs a 2 MB page table entry. The virtual memmap uses the same. > > There are *no* additional TLBs used. > > But why do you reserve an own virtual area then if you claim to not use any > additional mappings? The 1-1 area using mappings for 2MB pages right? So it uses a virtual 1-1 area. It already has a virtual mapping. What we do for virtual memmap here is also use 2MB pages but order the pages a bit different so that they provide a linear memory map. So the number of TLBs in use stays the same. There are a few additional higher level page table pages that are needed to provide the alternate view that generates the linear mapping but that is just a couple of pages. -- 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