[ckpatch][25/29] mm-decrease_minimum_dirty_ratio.patch

[Con Kolivas <kernel@kolivas.org>]

Make it possible to set dirty_ratio to 0, setting it to MAX_WRITEBACK_PAGES
when the value is ultra low, and set background to 0 when that is the case.

Signed-off-by: Con Kolivas <kernel@kolivas.org>

---
 mm/page-writeback.c |   10 ++++------
 1 files changed, 4 insertions(+), 6 deletions(-)

Index: linux-ck-dev/mm/page-writeback.c
===================================================================
--- linux-ck-dev.orig/mm/page-writeback.c	2006-06-18 15:20:11.000000000 +1000
+++ linux-ck-dev/mm/page-writeback.c	2006-06-18 15:25:16.000000000 +1000
@@ -126,9 +126,6 @@ static void get_writeback_state(struct w
  *
  * We only allow 1/2 of the currently-unmapped memory to be dirtied.
  *
- * We don't permit the clamping level to fall below 5% - that is getting rather
- * excessive.
- *
  * We make sure that the background writeout level is below the adjusted
  * clamping level.
  */
@@ -162,15 +159,16 @@ get_dirty_limits(struct writeback_state 
 	if (dirty_ratio > unmapped_ratio / 2)
 		dirty_ratio = unmapped_ratio / 2;
 
-	if (dirty_ratio < 5)
-		dirty_ratio = 5;
-
 	background_ratio = dirty_background_ratio;
 	if (background_ratio >= dirty_ratio)
 		background_ratio = dirty_ratio / 2;
 
 	background = (background_ratio * available_memory) / 100;
 	dirty = (dirty_ratio * available_memory) / 100;
+	if (dirty < MAX_WRITEBACK_PAGES) {
+		dirty = MAX_WRITEBACK_PAGES;
+		background = 0;
+	}
 	tsk = current;
 	if (tsk->flags & PF_LESS_THROTTLE || rt_task(tsk)) {
 		background += background / 4;

-- 
-ck