From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261819AbVEPUGx (ORCPT ); Mon, 16 May 2005 16:06:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261850AbVEPUGw (ORCPT ); Mon, 16 May 2005 16:06:52 -0400 Received: from serv01.siteground.net ([70.85.91.68]:5535 "EHLO serv01.siteground.net") by vger.kernel.org with ESMTP id S261819AbVEPUED (ORCPT ); Mon, 16 May 2005 16:04:03 -0400 Date: Mon, 16 May 2005 12:05:53 -0700 (PDT) From: christoph X-X-Sender: christoph@ScMPusgw To: linux-mm@kvack.org cc: linux-kernel@vger.kernel.org Subject: [PATCH] Factor in buddy allocator alignment requirements in node memory alignment Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - serv01.siteground.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [0 0] / [47 12] X-AntiAbuse: Sender Address Domain - scalex86.org X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Memory for nodes on i386 is currently aligned on 2 MB boundaries. However, the buddy allocator needs pages to be aligned on PAGE_SIZE << MAX_ORDER which is 8MB if MAX_ORDER = 11. The following patch determines the maximum alignment needed and will chose 2MB boundaries if MAX_ORDER is very low but will align correctly to a MAX_ORDER boundary if the alignment requirements of the page allocator are greater than 2MB. Signed-off-by: Christoph Lameter Signed-off-by: Shai Fultheim Index: linux-2.6.11/arch/i386/mm/discontig.c =================================================================== --- linux-2.6.11.orig/arch/i386/mm/discontig.c 2005-05-12 20:04:56.000000000 -0700 +++ linux-2.6.11/arch/i386/mm/discontig.c 2005-05-12 20:05:58.000000000 -0700 @@ -100,8 +100,6 @@ extern unsigned long max_low_pfn; extern unsigned long totalram_pages; extern unsigned long totalhigh_pages; -#define LARGE_PAGE_BYTES (PTRS_PER_PTE * PAGE_SIZE) - unsigned long node_remap_start_pfn[MAX_NUMNODES]; unsigned long node_remap_size[MAX_NUMNODES]; unsigned long node_remap_offset[MAX_NUMNODES]; @@ -185,6 +183,12 @@ static unsigned long calculate_numa_rema { int nid; unsigned long size, reserve_pages = 0; + /* + * Alignment is either to the PMD boundary or to the boundary of the + * largest order allowed by the buddy allocator whichever is bigger + */ + unsigned long alignment = (( 1 << MAX_ORDER ) > PTRS_PER_PTE) ? + 1 << MAX_ORDER : PTRS_PER_PTE; for_each_online_node(nid) { if (nid == 0) @@ -204,10 +208,10 @@ static unsigned long calculate_numa_rema /* ensure the remap includes space for the pgdat. */ size = node_remap_size[nid] + sizeof(pg_data_t); - /* convert size to large (pmd size) pages, rounding up */ - size = (size + LARGE_PAGE_BYTES - 1) / LARGE_PAGE_BYTES; + /* convert size to the alignment, rounding up */ + size = (size + (alignment * PAGE_SIZE) - 1) / (alignment * PAGE_SIZE); /* now the roundup is correct, convert to PAGE_SIZE pages */ - size = size * PTRS_PER_PTE; + size = size * alignment; printk("Reserving %ld pages of KVA for lmem_map of node %d\n", size, nid); node_remap_size[nid] = size;