Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932389AbWEZMER (ORCPT ); Fri, 26 May 2006 08:04:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932537AbWEZMEQ (ORCPT ); Fri, 26 May 2006 08:04:16 -0400 Received: from smtp.ustc.edu.cn ([202.38.64.16]:34777 "HELO ustc.edu.cn") by vger.kernel.org with SMTP id S932392AbWEZLxB (ORCPT ); Fri, 26 May 2006 07:53:01 -0400 Message-ID: <348644378.06563@ustc.edu.cn> X-EYOUMAIL-SMTPAUTH: wfg@mail.ustc.edu.cn Message-Id: <20060526115303.499451943@localhost.localdomain> References: <20060526113906.084341801@localhost.localdomain> Date: Fri, 26 May 2006 19:39:15 +0800 From: Wu Fengguang To: Andrew Morton Cc: linux-kernel@vger.kernel.org, Wu Fengguang Subject: [PATCH 09/33] readahead: {MIN,MAX}_RA_PAGES Content-Disposition: inline; filename=readahead-macros-min-max-rapages.patch Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1815 Lines: 54 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: Wu Fengguang --- mm/readahead.c | 14 ++++++++++++-- 1 files changed, 12 insertions(+), 2 deletions(-) --- linux-2.6.17-rc4-mm3.orig/mm/readahead.c +++ linux-2.6.17-rc4-mm3/mm/readahead.c @@ -17,13 +17,21 @@ #include #include +/* + * 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) + void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page) { } EXPORT_SYMBOL(default_unplug_io_fn); 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, @@ -52,7 +60,7 @@ static inline unsigned long get_max_read 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) -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/