From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 16 May 2005 12:05:53 -0700 (PDT) From: christoph 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 Sender: owner-linux-mm@kvack.org Return-Path: To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org List-ID: 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; -- 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: aart@kvack.org