Raise default dirty data limits, per:
http://marc.info/?l=linux-kernel&m=123707714231039&w=2

Also lower default swappiness from 60 to 40.

--- work-2.6.29.4.orig/mm/page-writeback.c
+++ work-2.6.29.4/mm/page-writeback.c
@@ -66,7 +66,7 @@ static inline long sync_writeback_pages(
 /*
  * Start background writeback (via pdflush) at this percentage
  */
-int dirty_background_ratio = 5;
+int dirty_background_ratio = 7;
 
 /*
  * dirty_background_bytes starts at 0 (disabled) so that it is a function of
@@ -83,7 +83,7 @@ int vm_highmem_is_dirtyable;
 /*
  * The generator of dirty data starts writeback at this percentage
  */
-int vm_dirty_ratio = 10;
+int vm_dirty_ratio = 15;
 
 /*
  * vm_dirty_bytes starts at 0 (disabled) so that it is a function of
@@ -94,12 +94,12 @@ unsigned long vm_dirty_bytes;
 /*
  * The interval between `kupdate'-style writebacks, in jiffies
  */
-int dirty_writeback_interval = 5 * HZ;
+int dirty_writeback_interval = 3 * HZ;
 
 /*
  * The longest number of jiffies for which data is allowed to remain dirty
  */
-int dirty_expire_interval = 30 * HZ;
+int dirty_expire_interval = 10 * HZ;
 
 /*
  * Flag that makes the machine dump writes/reads and block dirtyings.
--- work-2.6.29.4.orig/mm/vmscan.c
+++ work-2.6.29.4/mm/vmscan.c
@@ -118,7 +118,7 @@ struct scan_control {
 /*
  * From 0 .. 100.  Higher means more swappy.
  */
-int vm_swappiness = 60;
+int vm_swappiness = 40;
 long vm_total_pages;	/* The total number of pages which the VM controls */
 
 static LIST_HEAD(shrinker_list);