further tweaks - add vm.min_free_kbytes=20480

systemvm/debian/etc/sysctl.conf

@@ -66,3 +66,6 @@ vm.swappiness=1
 
 # make the kernel more aggressive in reclaiming RAM from the disk and swap caches
 vm.vfs_cache_pressure = 200
+
+# try to maintain 'free' memory thereby reducing the size of disk cache, hence reducing swapping.
+vm.min_free_kbytes = 20480

systemvm/debian/opt/cloud/bin/setup/cloud-early-config

@@ -206,10 +206,10 @@ patch() {
   physmem=$(free|awk '/^Mem:/{print $2}')
   case $physmem in
     [1-4095999])
-      sysctl -w vm.vfs_cache_pressure=200
+      sed  -i "/^vm.vfs_cache_pressure/ c\vm.vfs_cache_pressure = 200" /etc/sysctl.conf
       ;;
     *)
-      sysctl -w vm.vfs_cache_pressure=100
+      sed  -i "/^vm.vfs_cache_pressure/ c\vm.vfs_cache_pressure = 100" /etc/sysctl.conf
       ;;
   esac