Index: linux-2.6.7/include/linux/swap.h
===================================================================
--- linux-2.6.7.orig/include/linux/swap.h	2004-06-16 17:35:46.000000000 +1000
+++ linux-2.6.7/include/linux/swap.h	2004-07-08 18:34:09.182387154 +1000
@@ -175,6 +175,7 @@
 extern int try_to_free_pages(struct zone **, unsigned int, unsigned int);
 extern int shrink_all_memory(int);
 extern int vm_swappiness;
+extern int vm_autoregulate;
 
 #ifdef CONFIG_MMU
 /* linux/mm/shmem.c */
Index: linux-2.6.7/include/linux/sysctl.h
===================================================================
--- linux-2.6.7.orig/include/linux/sysctl.h	2004-06-16 17:35:46.000000000 +1000
+++ linux-2.6.7/include/linux/sysctl.h	2004-07-08 18:34:09.183386997 +1000
@@ -164,6 +164,7 @@
 	VM_LAPTOP_MODE=23,	/* vm laptop mode */
 	VM_BLOCK_DUMP=24,	/* block dump mode */
 	VM_HUGETLB_GROUP=25,	/* permitted hugetlb group */
+	VM_AUTOREGULATE=26,     /* swappiness and inactivation autoregulated */
 };
 
 
Index: linux-2.6.7/kernel/sysctl.c
===================================================================
--- linux-2.6.7.orig/kernel/sysctl.c	2004-06-16 17:35:46.000000000 +1000
+++ linux-2.6.7/kernel/sysctl.c	2004-07-08 18:34:09.185386684 +1000
@@ -727,6 +727,14 @@
 		.extra1		= &zero,
 		.extra2		= &one_hundred,
 	},
+	{
+		.ctl_name	= VM_AUTOREGULATE,
+		.procname	= "autoregulate",
+		.data		= &vm_autoregulate,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec,
+	},
 #ifdef CONFIG_HUGETLB_PAGE
 	 {
 		.ctl_name	= VM_HUGETLB_PAGES,
Index: linux-2.6.7/mm/vmscan.c
===================================================================
--- linux-2.6.7.orig/mm/vmscan.c	2004-06-16 17:35:46.000000000 +1000
+++ linux-2.6.7/mm/vmscan.c	2004-07-08 18:34:09.186386528 +1000
@@ -43,6 +43,8 @@
  * From 0 .. 100.  Higher means more swappy.
  */
 int vm_swappiness = 60;
+int vm_autoregulate = 1;
+static int app_percent = 1;
 static long total_memory;
 
 #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
@@ -648,7 +650,9 @@
 	long mapped_ratio;
 	long distress;
 	long swap_tendency;
+	struct sysinfo i;
 
+	si_meminfo(&i);
 	lru_add_drain();
 	pgmoved = 0;
 	spin_lock_irq(&zone->lru_lock);
@@ -691,6 +695,42 @@
 	mapped_ratio = (sc->nr_mapped * 100) / total_memory;
 
 	/*
+	 * app_percent is the percentage of physical ram used
+	 * by application pages.
+	 */
+	si_meminfo(&i);
+#ifdef CONFIG_SWAP
+	app_percent = 100 - ((i.freeram + get_page_cache_size() -
+		swapper_space.nrpages) / (i.totalram / 100));
+
+	if (vm_autoregulate) {
+		si_swapinfo(&i);
+			
+		if (likely(i.totalswap >= 100)) {
+			int swap_centile;
+	
+	
+			/*
+			 * swap_centile is the percentage of the last (sizeof physical
+			 * ram) of swap free.
+			 */
+			swap_centile = i.freeswap / 
+				(min(i.totalswap, i.totalram) / 100);
+			/*
+			 * Autoregulate vm_swappiness to be equal to the lowest of
+			 * app_percent and swap_centile.  Bias it downwards -ck
+			 */
+			vm_swappiness = min(app_percent, swap_centile);
+			vm_swappiness = vm_swappiness * vm_swappiness / 100;
+		} else 
+			vm_swappiness = 0;
+	}
+#else
+	app_percent = 100 - ((i.freeram + get_page_cache_size()) / 
+		(i.totalram / 100));
+#endif
+	
+	/*
 	 * Now decide how much we really want to unmap some pages.  The mapped
 	 * ratio is downgraded - just because there's a lot of mapped memory
 	 * doesn't necessarily mean that page reclaim isn't succeeding.
@@ -798,11 +838,16 @@
 static void
 shrink_zone(struct zone *zone, struct scan_control *sc)
 {
-	unsigned long scan_active, scan_inactive;
-	int count;
+	unsigned long scan_active, scan_inactive, biased_active;
+	int count, biased_ap;
 
 	scan_inactive = (zone->nr_active + zone->nr_inactive) >> sc->priority;
 
+	if (vm_autoregulate) {
+		biased_ap = app_percent * app_percent / 100;
+		biased_active = zone->nr_active / (101 - biased_ap) * 100;
+	} else
+		biased_active = zone->nr_active;
 	/*
 	 * Try to keep the active list 2/3 of the size of the cache.  And
 	 * make sure that refill_inactive is given a decent number of pages.
@@ -813,7 +858,7 @@
 	 * `scan_active' just to make sure that the kernel will slowly sift
 	 * through the active list.
 	 */
-	if (zone->nr_active >= 4*(zone->nr_inactive*2 + 1)) {
+	if (biased_active >= 4*(zone->nr_inactive*2 + 1)) {
 		/* Don't scan more than 4 times the inactive list scan size */
 		scan_active = 4*scan_inactive;
 	} else {
@@ -821,7 +866,7 @@
 
 		/* Cast to long long so the multiply doesn't overflow */
 
-		tmp = (unsigned long long)scan_inactive * zone->nr_active;
+		tmp = (unsigned long long)scan_inactive * biased_active;
 		do_div(tmp, zone->nr_inactive*2 + 1);
 		scan_active = (unsigned long)tmp;
 	}