mm: Add min_free_order_shift tunable.

By default the kernel tries to keep half as much memory free at each
order as it does for one order below. This can be too agressive when
running without swap.

Signed-off-by: Arve Hjønnevåg <arve@android.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 5c44ed49ca93..a596bfd766f6 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -119,6 +119,7 @@ static char * const zone_names[MAX_NR_ZONES] = {
 };
 
 int min_free_kbytes = 1024;
+int min_free_order_shift = 1;
 
 unsigned long __meminitdata nr_kernel_pages;
 unsigned long __meminitdata nr_all_pages;
@@ -1256,7 +1257,7 @@ int zone_watermark_ok(struct zone *z, int order, unsigned long mark,
 		free_pages -= z->free_area[o].nr_free << o;
 
 		/* Require fewer higher order pages to be free */
-		min >>= 1;
+		min >>= min_free_order_shift;
 
 		if (free_pages <= min)
 			return 0;