Index: linux-2.6.7-mm6/include/linux/swap.h
===================================================================
--- linux-2.6.7-mm6.orig/include/linux/swap.h	2004-07-05 19:41:48.000000000 +1000
+++ linux-2.6.7-mm6/include/linux/swap.h	2004-07-05 23:18:01.980100050 +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 auto_swappiness;
 
 #ifdef CONFIG_MMU
 /* linux/mm/shmem.c */
Index: linux-2.6.7-mm6/include/linux/sysctl.h
===================================================================
--- linux-2.6.7-mm6.orig/include/linux/sysctl.h	2004-07-05 19:44:05.000000000 +1000
+++ linux-2.6.7-mm6/include/linux/sysctl.h	2004-07-05 23:18:38.651379506 +1000
@@ -167,6 +167,7 @@
 	VM_BLOCK_DUMP=24,	/* block dump mode */
 	VM_HUGETLB_GROUP=25,	/* permitted hugetlb group */
 	VM_VFS_CACHE_PRESSURE=26, /* dcache/icache reclaim pressure */
+	VM_AUTO_SWAPPINESS=27,	/* Make vm_swappiness autoregulated */
 };
 
 
Index: linux-2.6.7-mm6/kernel/sysctl.c
===================================================================
--- linux-2.6.7-mm6.orig/kernel/sysctl.c	2004-07-05 19:44:05.000000000 +1000
+++ linux-2.6.7-mm6/kernel/sysctl.c	2004-07-05 23:18:01.983099583 +1000
@@ -727,6 +727,14 @@
 		.extra1		= &zero,
 		.extra2		= &one_hundred,
 	},
+	{
+		.ctl_name	= VM_AUTO_SWAPPINESS,
+		.procname	= "autoswappiness",
+		.data		= &auto_swappiness,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec,
+	},
 #ifdef CONFIG_HUGETLB_PAGE
 	 {
 		.ctl_name	= VM_HUGETLB_PAGES,
Index: linux-2.6.7-mm6/mm/vmscan.c
===================================================================
--- linux-2.6.7-mm6.orig/mm/vmscan.c	2004-07-05 19:41:49.000000000 +1000
+++ linux-2.6.7-mm6/mm/vmscan.c	2004-07-05 23:18:01.984099427 +1000
@@ -119,6 +119,7 @@
  * From 0 .. 100.  Higher means more swappy.
  */
 int vm_swappiness = 60;
+int auto_swappiness = 1;
 static long total_memory;
 
 static LIST_HEAD(shrinker_list);
@@ -691,6 +692,41 @@
 	 */
 	mapped_ratio = (sc->nr_mapped * 100) / total_memory;
 
+#ifdef CONFIG_SWAP
+	if (auto_swappiness) {
+		int app_percent;
+		struct sysinfo i;
+		
+		si_swapinfo(&i);
+			
+		if (likely(i.totalswap >= 100)) {
+			int swap_centile;
+	
+			/*
+			 * app_percent is the percentage of physical ram used
+			 * by application pages.
+			 */
+			si_meminfo(&i);
+			app_percent = 100 - ((i.freeram + get_page_cache_size() -
+				swapper_space.nrpages) / (i.totalram / 100));
+	
+			/*
+			 * 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;
+	}
+#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