The patch titled
readahead: laptop mode
has been removed from the -mm tree. Its filename is
readahead-laptop-mode.patch
This patch was probably dropped from -mm because
it has now been merged into a subsystem tree or
into Linus's tree, or because it was folded into
its parent patch in the -mm tree.
------------------------------------------------------
Subject: readahead: laptop mode
From: Wu Fengguang <wfg@xxxxxxxxxxxxxxxx>
When the laptop drive is spinned down, defer look-ahead to spin up time.
The implementation employs a poll based method, for performance is not a
concern in this code path. The poll interval is 64KB, which should be small
enough for movies/musics. The user space application is responsible for
proper caching to hide the spin-up-and-read delay.
------------------------------------------------------------------------
For crazy laptop users who prefer aggressive read-ahead, here is the way:
# echo 1000 > /proc/sys/vm/readahead_ratio
# blockdev --setra 524280 /dev/hda # this is the max possible value
Notes:
- It is still an untested feature.
- It is safer to use blockdev+fadvise to increase ra-max for a single file,
which needs patching your movie player.
- Be sure to restore them to sane values in normal operations!
Signed-off-by: Wu Fengguang <wfg@xxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
include/linux/writeback.h | 6 ++++++
mm/page-writeback.c | 2 +-
mm/readahead.c | 31 +++++++++++++++++++++++++++++++
3 files changed, 38 insertions(+), 1 deletion(-)
diff -puN include/linux/writeback.h~readahead-laptop-mode include/linux/writeback.h
--- 25/include/linux/writeback.h~readahead-laptop-mode Fri May 26 13:34:37 2006
+++ 25-akpm/include/linux/writeback.h Fri May 26 13:34:37 2006
@@ -86,6 +86,12 @@ void laptop_io_completion(void);
void laptop_sync_completion(void);
void throttle_vm_writeout(void);
+extern struct timer_list laptop_mode_wb_timer;
+static inline int laptop_spinned_down(void)
+{
+ return !timer_pending(&laptop_mode_wb_timer);
+}
+
/* These are exported to sysctl. */
extern int dirty_background_ratio;
extern int vm_dirty_ratio;
diff -puN mm/page-writeback.c~readahead-laptop-mode mm/page-writeback.c
--- 25/mm/page-writeback.c~readahead-laptop-mode Fri May 26 13:34:37 2006
+++ 25-akpm/mm/page-writeback.c Fri May 26 13:34:37 2006
@@ -378,7 +378,7 @@ static void wb_timer_fn(unsigned long un
static void laptop_timer_fn(unsigned long unused);
static DEFINE_TIMER(wb_timer, wb_timer_fn, 0, 0);
-static DEFINE_TIMER(laptop_mode_wb_timer, laptop_timer_fn, 0, 0);
+DEFINE_TIMER(laptop_mode_wb_timer, laptop_timer_fn, 0, 0);
/*
* Periodic writeback of "old" data.
diff -puN mm/readahead.c~readahead-laptop-mode mm/readahead.c
--- 25/mm/readahead.c~readahead-laptop-mode Fri May 26 13:34:37 2006
+++ 25-akpm/mm/readahead.c Fri May 26 13:34:37 2006
@@ -16,6 +16,7 @@
#include <linux/blkdev.h>
#include <linux/backing-dev.h>
#include <linux/pagevec.h>
+#include <linux/writeback.h>
#include <asm/div64.h>
/*
@@ -795,6 +796,31 @@ out:
}
/*
+ * Set a new look-ahead mark at @new_index.
+ * Return 0 if the new mark is successfully set.
+ */
+static inline int renew_lookahead(struct address_space *mapping,
+ struct file_ra_state *ra,
+ pgoff_t index, pgoff_t new_index)
+{
+ struct page *page;
+
+ if (index == ra->lookahead_index &&
+ new_index >= ra->readahead_index)
+ return 1;
+
+ page = radix_tree_lookup(&mapping->page_tree, new_index);
+ if (!page)
+ return 1;
+
+ SetPageReadahead(page);
+ if (ra->lookahead_index == index)
+ ra->lookahead_index = new_index;
+
+ return 0;
+}
+
+/*
* Update `backing_dev_info.ra_thrash_bytes' to be a _biased_ average of
* read-ahead sizes. Which makes it an a-bit-risky(*) estimation of the
* _minimal_ read-ahead thrashing threshold on the device.
@@ -1732,6 +1758,11 @@ page_cache_readahead_adaptive(struct add
end_index - index);
return 0;
}
+ if (laptop_mode && laptop_spinned_down()) {
+ if (!renew_lookahead(mapping, ra, index,
+ index + LAPTOP_POLL_INTERVAL))
+ return 0;
+ }
}
if (page)
_
Patches currently in -mm which might be from wfg@xxxxxxxxxxxxxxxx are
readahead-laptop-mode.patch
readahead-loop-case.patch
readahead-nfsd-case.patch
readahead-turn-on-by-default.patch
readahead-debug-radix-tree-new-functions.patch
readahead-debug-traces-showing-accessed-file-names.patch
readahead-debug-traces-showing-read-patterns.patch
-
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