Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750990AbXA0IY2 (ORCPT ); Sat, 27 Jan 2007 03:24:28 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752198AbXA0IY1 (ORCPT ); Sat, 27 Jan 2007 03:24:27 -0500 Received: from smtp.ustc.edu.cn ([202.38.64.16]:34842 "HELO ustc.edu.cn" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with SMTP id S1750990AbXA0IY0 (ORCPT ); Sat, 27 Jan 2007 03:24:26 -0500 Message-ID: <369886263.27547@ustc.edu.cn> X-EYOUMAIL-SMTPAUTH: wfg@mail.ustc.edu.cn Message-Id: <20070127082529.253596257@mail.ustc.edu.cn> References: <20070127080219.161473179@mail.ustc.edu.cn> User-Agent: quilt/0.45-1 Date: Sat, 27 Jan 2007 16:02:21 +0800 From: Fengguang Wu To: Andrew Morton Cc: Martin Peschke , linux-kernel@vger.kernel.org Subject: [PATCH 2/8] readahead: state based method routines: explicitly embed class_new/class_old inside flags Content-Disposition: inline; filename=readahead-state-based-method-routines-explicitly-embed-class_new-class_old-inside-flags.patch Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2399 Lines: 79 The new/old ra class were implicitly stored in low bits of file_ra_state.flags. Now make the data structure obvious, and remove the coding tricks. Signed-off-by: Fengguang Wu --- include/linux/fs.h | 9 ++++++++- mm/readahead.c | 18 ++++-------------- 2 files changed, 12 insertions(+), 15 deletions(-) --- linux-2.6.20-rc4-mm1.orig/include/linux/fs.h +++ linux-2.6.20-rc4-mm1/include/linux/fs.h @@ -738,7 +738,14 @@ struct file_ra_state { unsigned long mmap_hit; /* Cache hit stat for mmap accesses */ unsigned long mmap_miss; /* Cache miss stat for mmap accesses */ - unsigned long flags; /* RA_FLAG_xxx | ra_class_old | ra_class_new */ + union { + unsigned long flags; /* RA_FLAG_xxx | class_old | class_new */ + struct { + u8 class_new; + u8 class_old; + }; + }; + unsigned long prev_page; /* Cache last read() position */ unsigned long ra_pages; /* Maximum readahead window */ }; --- linux-2.6.20-rc4-mm1.orig/mm/readahead.c +++ linux-2.6.20-rc4-mm1/mm/readahead.c @@ -48,8 +48,6 @@ int readahead_hit_rate = 1; /* * Detailed classification of read-ahead behaviors. */ -#define RA_CLASS_SHIFT 4 -#define RA_CLASS_MASK ((1 << RA_CLASS_SHIFT) - 1) enum ra_class { RA_CLASS_ALL, RA_CLASS_INITIAL, @@ -795,12 +793,12 @@ out: static enum ra_class ra_class_new(struct file_ra_state *ra) { - return ra->flags & RA_CLASS_MASK; + return ra->class_new; } static inline enum ra_class ra_class_old(struct file_ra_state *ra) { - return (ra->flags >> RA_CLASS_SHIFT) & RA_CLASS_MASK; + return ra->class_old; } static unsigned long ra_readahead_size(struct file_ra_state *ra) @@ -832,16 +830,8 @@ static int ra_has_index(struct file_ra_s */ static void ra_set_class(struct file_ra_state *ra, enum ra_class ra_class) { - unsigned long flags_mask; - unsigned long flags; - unsigned long old_ra_class; - - flags_mask = ~(RA_CLASS_MASK | (RA_CLASS_MASK << RA_CLASS_SHIFT)); - flags = ra->flags & flags_mask; - - old_ra_class = ra_class_new(ra) << RA_CLASS_SHIFT; - - ra->flags = flags | old_ra_class | ra_class; + ra->class_old = ra->class_new; + ra->class_new = ra_class; } /* -- - 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/