From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 19 Jul 2007 16:25:29 -0700 From: Andrew Morton Subject: Re: [PATCH 4/7] x86_64: SPARSEMEM_VMEMMAP 2M page size support Message-Id: <20070719162529.66302406.akpm@linux-foundation.org> In-Reply-To: References: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Andy Whitcroft Cc: linux-mm@kvack.org, linux-arch@vger.kernel.org, Nick Piggin , Christoph Lameter , Mel Gorman List-ID: On Fri, 13 Jul 2007 14:36:39 +0100 Andy Whitcroft wrote: > x86_64 uses 2M page table entries to map its 1-1 kernel space. > We also implement the virtual memmap using 2M page table entries. So > there is no additional runtime overhead over FLATMEM, initialisation > is slightly more complex. As FLATMEM still references memory to > obtain the mem_map pointer and SPARSEMEM_VMEMMAP uses a compile > time constant, SPARSEMEM_VMEMMAP should be superior. > > With this SPARSEMEM becomes the most efficient way of handling > virt_to_page, pfn_to_page and friends for UP, SMP and NUMA on x86_64. > > [apw@shadowen.org: code resplit, style fixups] > From: Christoph Lameter > Signed-off-by: Christoph Lameter > Signed-off-by: Andy Whitcroft > Acked-by: Mel Gorman > --- > diff --git a/Documentation/x86_64/mm.txt b/Documentation/x86_64/mm.txt Please put the From: attribution right at the top of the changelog. Please alter your scripts to include diffstat output after the ^--- Thanks. -- 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