---
 Documentation/sysctl/vm.txt   |   14 ++++++++++----
 include/linux/swap-prefetch.h |    5 +++++
 mm/swap_prefetch.c            |   11 +++++++++++
 3 files changed, 26 insertions(+), 4 deletions(-)

Index: linux-2.6.16-ck1/include/linux/swap-prefetch.h
===================================================================
--- linux-2.6.16-ck1.orig/include/linux/swap-prefetch.h	2006-03-20 20:46:55.000000000 +1100
+++ linux-2.6.16-ck1/include/linux/swap-prefetch.h	2006-03-20 20:47:01.000000000 +1100
@@ -33,6 +33,7 @@ extern void add_to_swapped_list(struct p
 extern void remove_from_swapped_list(const unsigned long index);
 extern void delay_swap_prefetch(void);
 extern void prepare_swap_prefetch(void);
+extern void aggressive_swap_prefetch(void);
 
 #else	/* CONFIG_SWAP_PREFETCH */
 static inline void add_to_swapped_list(struct page *__unused)
@@ -50,6 +51,10 @@ static inline void remove_from_swapped_l
 static inline void delay_swap_prefetch(void)
 {
 }
+
+static inline void aggressive_swap_prefetch(void)
+{
+}
 #endif	/* CONFIG_SWAP_PREFETCH */
 
 #endif		/* SWAP_PREFETCH_H_INCLUDED */
Index: linux-2.6.16-ck1/mm/swap_prefetch.c
===================================================================
--- linux-2.6.16-ck1.orig/mm/swap_prefetch.c	2006-03-20 20:47:00.000000000 +1100
+++ linux-2.6.16-ck1/mm/swap_prefetch.c	2006-03-20 20:47:01.000000000 +1100
@@ -29,6 +29,7 @@
 
 #define PREFETCH_NORMAL		(1 << 0)
 #define PREFETCH_AGGRESSIVE 	(1 << 1)
+
 /*
  * sysctl - enable/disable swap prefetching bits
  * This is composed of the bitflags PREFETCH_NORMAL and PREFETCH_AGGRESSIVE.
@@ -601,6 +602,16 @@ void __init prepare_swap_prefetch(void)
 	}
 }
 
+/*
+ * This exported function sets the PREFETCH_AGGRESSIVE flag but only if there
+ * are entries to prefetch.
+ */
+void aggressive_swap_prefetch(void)
+{
+	if (swapped.count)
+		swap_prefetch |= PREFETCH_AGGRESSIVE;
+}
+
 static int __init kprefetchd_init(void)
 {
 	kprefetchd_task = kthread_run(kprefetchd, NULL, "kprefetchd");
Index: linux-2.6.16-ck1/Documentation/sysctl/vm.txt
===================================================================
--- linux-2.6.16-ck1.orig/Documentation/sysctl/vm.txt	2006-03-20 20:47:00.000000000 +1100
+++ linux-2.6.16-ck1/Documentation/sysctl/vm.txt	2006-03-20 20:47:01.000000000 +1100
@@ -192,9 +192,15 @@ This is value ORed together of
 1	= Normal background swap prefetching when load is light
 2	= Aggressively swap prefetch as much as possible
 
-When 2 is set, after the maximum amount possible has been prefetched, this bit
-is unset. ie Setting the value to 3 will prefetch aggressively then drop to 1.
-This is useful for doing aggressive prefetching for short periods in scripts
-such as after resuming from software suspend.
+ie Setting the value to 3 will prefetch aggressively then drop to 1. This
+is useful for doing aggressive prefetching for short periods in scripts
+such as after resuming from software suspend. Setting the value to 2 will
+prefetch aggressively as much as it can and then disable any further swap
+prefetching.
+
+Note that setting this to 0 disables even storing a list of swapped pages (to
+minimise overhead) which means that if significant swapping has occurred with
+swap_prefetch unset and then it is enabled, there is nothing that can be
+prefetched.
 
 The default value is 1.