From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with SMTP id 0D5B76B0055 for ; Wed, 14 Oct 2009 20:58:53 -0400 (EDT) Date: Thu, 15 Oct 2009 01:58:51 +0100 (BST) From: Hugh Dickins Subject: [PATCH 9/9] swap_info: reorder its fields In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: Andrew Morton Cc: KAMEZAWA Hiroyuki , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: Reorder (and comment) the fields of swap_info_struct, to make better use of its cachelines: it's good for swap_duplicate() in particular if unsigned int max and swap_map are near the start. Signed-off-by: Hugh Dickins --- include/linux/swap.h | 26 +++++++++++++------------- 1 file changed, 13 insertions(+), 13 deletions(-) --- si8/include/linux/swap.h 2009-10-14 21:27:07.000000000 +0100 +++ si9/include/linux/swap.h 2009-10-14 21:27:14.000000000 +0100 @@ -167,21 +167,21 @@ struct swap_info_struct { signed short prio; /* swap priority of this type */ signed char type; /* strange name for an index */ signed char next; /* next type on the swap list */ - struct file *swap_file; - struct block_device *bdev; - struct swap_extent first_swap_extent; - struct swap_extent *curr_swap_extent; - unsigned char *swap_map; - unsigned int lowest_bit; - unsigned int highest_bit; + unsigned int max; /* extent of the swap_map */ + unsigned char *swap_map; /* vmalloc'ed array of usage counts */ + unsigned int lowest_bit; /* index of first free in swap_map */ + unsigned int highest_bit; /* index of last free in swap_map */ + unsigned int pages; /* total of usable pages of swap */ + unsigned int inuse_pages; /* number of those currently in use */ + unsigned int cluster_next; /* likely index for next allocation */ + unsigned int cluster_nr; /* countdown to next cluster search */ unsigned int lowest_alloc; /* while preparing discard cluster */ unsigned int highest_alloc; /* while preparing discard cluster */ - unsigned int cluster_next; - unsigned int cluster_nr; - unsigned int pages; - unsigned int max; - unsigned int inuse_pages; - unsigned int old_block_size; + struct swap_extent *curr_swap_extent; + struct swap_extent first_swap_extent; + struct block_device *bdev; /* swap device or bdev of swap file */ + struct file *swap_file; /* seldom referenced */ + unsigned int old_block_size; /* seldom referenced */ }; struct swap_list_t { -- 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