From: Fengguang Wu <wfg@mail.ustc.edu.cn>
To: Andrew Morton <akpm@osdl.org>
Cc: Martin Peschke <mp3@de.ibm.com>, linux-kernel@vger.kernel.org
Subject: [PATCH 1/8] readahead: min/max sizes: increase VM_MIN_READAHEAD to 32KB
Date: Sat, 27 Jan 2007 16:02:20 +0800 [thread overview]
Message-ID: <369886263.49250@ustc.edu.cn> (raw)
Message-ID: <20070127082529.094875235@mail.ustc.edu.cn> (raw)
In-Reply-To: 20070127080219.161473179@mail.ustc.edu.cn
[-- Attachment #1: readahead-min-max-sizes-increase-VM_MIN_READAHEAD-to-32KB.patch --]
[-- Type: text/plain, Size: 1004 bytes --]
Use a minimal readahead size of 32KB instead of 16KB for the adaptive readahead.
The potential benefit(disk utilization in worst case doubles) is large, while
the potential panelty is small(wastes up to 32MB when thrashed/missed 1000 times).
This minimal value is only applied for sequential streams.
Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
---
include/linux/mm.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- linux-2.6.20-rc4-mm1.orig/include/linux/mm.h
+++ linux-2.6.20-rc4-mm1/include/linux/mm.h
@@ -1069,10 +1069,11 @@ int write_one_page(struct page *page, in
/* readahead.c */
#ifdef CONFIG_ADAPTIVE_READAHEAD
#define VM_MAX_READAHEAD 1024 /* kbytes */
+#define VM_MIN_READAHEAD 32 /* kbytes (includes current page) */
#else
#define VM_MAX_READAHEAD 128 /* kbytes */
-#endif
#define VM_MIN_READAHEAD 16 /* kbytes (includes current page) */
+#endif
#define VM_MAX_CACHE_HIT 256 /* max pages in a row in cache before
* turning readahead off */
--
next prev parent reply other threads:[~2007-01-27 8:24 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20070127080219.161473179@mail.ustc.edu.cn>
2007-01-27 8:02 ` [PATCH 0/8] readahead updates Fengguang Wu
[not found] ` <20070127082529.094875235@mail.ustc.edu.cn>
2007-01-27 8:02 ` Fengguang Wu [this message]
[not found] ` <20070127082529.253596257@mail.ustc.edu.cn>
2007-01-27 8:02 ` [PATCH 2/8] readahead: state based method routines: explicitly embed class_new/class_old inside flags Fengguang Wu
[not found] ` <20070127082529.463795013@mail.ustc.edu.cn>
2007-01-27 8:02 ` [PATCH 3/8] readahead: state based method: prevent tiny size Fengguang Wu
[not found] ` <20070127082529.616795882@mail.ustc.edu.cn>
2007-01-27 8:02 ` [PATCH 4/8] readahead: state based method: move readahead_ratio out of compute_thrashing_threshold() Fengguang Wu
[not found] ` <20070127082529.796556490@mail.ustc.edu.cn>
2007-01-27 8:02 ` [PATCH 5/8] readahead: initial method: user recommended size: rename to read_ahead_initial_kb Fengguang Wu
[not found] ` <20070127082530.010446696@mail.ustc.edu.cn>
2007-01-27 8:02 ` [PATCH 6/8] readahead: thrashing recovery method fix Fengguang Wu
[not found] ` <20070127082530.137014081@mail.ustc.edu.cn>
2007-01-27 8:02 ` [PATCH 7/8] readahead: call scheme: fix thrashed unaligned read Fengguang Wu
[not found] ` <20070127082530.379485097@mail.ustc.edu.cn>
2007-01-27 8:02 ` [PATCH 8/8] readahead: laptop mode fix Fengguang Wu
2007-01-31 13:37 ` [PATCH 0/8] readahead updates martin
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