From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764017AbXHVJLp (ORCPT ); Wed, 22 Aug 2007 05:11:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758959AbXHVIxx (ORCPT ); Wed, 22 Aug 2007 04:53:53 -0400 Received: from 1wt.eu ([62.212.114.60]:2174 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758164AbXHVIxs (ORCPT ); Wed, 22 Aug 2007 04:53:48 -0400 From: Willy Tarreau Message-Id: <20070822084022.%N@1wt.eu> References: <20070822083844.%N@1wt.eu> User-Agent: quilt/0.46-1 Date: Wed, 22 Aug 2007 11:39:15 +0200 To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: Fengguang Wu , Steven Pratt , Ram Pai , Rusty Russell , Andrew Morton , Greg Kroah-Hartman , Willy Tarreau Subject: [2.6.20.17 review 31/58] readahead: MIN_RA_PAGES/MAX_RA_PAGES macros Content-Disposition: inline; filename=0031-readahead-MIN_RA_PAGES-MAX_RA_PAGES-macros.patch Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Define two convenient macros for read-ahead: - MAX_RA_PAGES: rounded down counterpart of VM_MAX_READAHEAD - MIN_RA_PAGES: rounded _up_ counterpart of VM_MIN_READAHEAD Note that the rounded up MIN_RA_PAGES will work flawlessly with _large_ page sizes like 64k. Signed-off-by: Fengguang Wu Cc: Steven Pratt Cc: Ram Pai Cc: Rusty Russell Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman Signed-off-by: Willy Tarreau --- mm/readahead.c | 12 ++++++++++-- 1 files changed, 10 insertions(+), 2 deletions(-) diff --git a/mm/readahead.c b/mm/readahead.c index 0f539e8..f26cdea 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -21,8 +21,16 @@ void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page) } EXPORT_SYMBOL(default_unplug_io_fn); +/* + * Convienent macros for min/max read-ahead pages. + * Note that MAX_RA_PAGES is rounded down, while MIN_RA_PAGES is rounded up. + * The latter is necessary for systems with large page size(i.e. 64k). + */ +#define MAX_RA_PAGES (VM_MAX_READAHEAD*1024 / PAGE_CACHE_SIZE) +#define MIN_RA_PAGES DIV_ROUND_UP(VM_MIN_READAHEAD*1024, PAGE_CACHE_SIZE) + struct backing_dev_info default_backing_dev_info = { - .ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE, + .ra_pages = MAX_RA_PAGES, .state = 0, .capabilities = BDI_CAP_MAP_COPY, .unplug_io_fn = default_unplug_io_fn, @@ -51,7 +59,7 @@ static inline unsigned long get_max_readahead(struct file_ra_state *ra) static inline unsigned long get_min_readahead(struct file_ra_state *ra) { - return (VM_MIN_READAHEAD * 1024) / PAGE_CACHE_SIZE; + return MIN_RA_PAGES; } static inline void reset_ahead_window(struct file_ra_state *ra) -- 1.5.2.5 --