# This is a BitKeeper generated diff -Nru style patch.
#
# ChangeSet
#   2004/11/15 19:53:53-08:00 piggin@cyberone.com.au 
#   [PATCH] mm: tune the page allocator thresholds
#   
#   without patch:
#         pages_min   pages_low   pages_high
#   dma        4          8          12
#   normal   234        468         702
#   high     128        256         384
#   
#   with patch:
#         pages_min   pages_low   pages_high
#   dma       17         21          25
#   normal   939       1173        1408
#   high     128        160         192
#   
#   without patch:
#                                | GFP_KERNEL        | GFP_ATOMIC
#   allocate immediately         |   9 dma, 469 norm |  9 dma, 469 norm
#   allocate after waking kswapd |   5 dma, 234 norm |  3 dma,  88 norm
#   allocate after synch reclaim |   5 dma, 234 norm |  n/a
#   
#   with patch:
#                                | GFP_KERNEL         | GFP_ATOMIC
#   allocate immediately         |  22 dma, 1174 norm | 22 dma, 1174 norm
#   allocate after waking kswapd |  18 dma,  940 norm |  6 dma,  440 norm
#   allocate after synch reclaim |  18 dma,  940 norm |  n/a
#   
#   So the buffer between GFP_KERNEL and GFP_ATOMIC allocations is:
#   
#   2.6.8      | 465 dma, 117 norm, 582 tot = 2328K
#   2.6.10-rc  |   2 dma, 146 norm, 148 tot =  592K
#   patch      |  12 dma, 500 norm, 512 tot = 2048K
#   
#   Which is getting pretty good.
#   
#   kswap starts at:
#   2.6.8     477 dma, 496 norm, 973 total
#   2.6.10-rc   8 dma, 468 norm, 476 total
#   patched    17 dma, 939 norm, 956 total
#   
#   So in terms of total pages, that's looking similar to 2.6.8.
#   
#   Signed-off-by: Andrew Morton <akpm@osdl.org>
#   Signed-off-by: Linus Torvalds <torvalds@osdl.org>
# 
# mm/page_alloc.c
#   2004/11/15 19:29:07-08:00 piggin@cyberone.com.au +23 -18
#   mm: tune the page allocator thresholds
# 
diff -Nru a/mm/page_alloc.c b/mm/page_alloc.c
--- a/mm/page_alloc.c	2004-11-16 15:34:58 -08:00
+++ b/mm/page_alloc.c	2004-11-16 15:34:58 -08:00
@@ -1945,8 +1945,12 @@
 			                   lowmem_pages;
 		}
 
-		zone->pages_low = zone->pages_min * 2;
-		zone->pages_high = zone->pages_min * 3;
+		/*
+		 * When interpreting these watermarks, just keep in mind that:
+		 * zone->pages_min == (zone->pages_min * 4) / 4;
+		 */
+		zone->pages_low   = (zone->pages_min * 5) / 4;
+		zone->pages_high  = (zone->pages_min * 6) / 4;
 		spin_unlock_irqrestore(&zone->lru_lock, flags);
 	}
 }
@@ -1955,24 +1959,25 @@
  * Initialise min_free_kbytes.
  *
  * For small machines we want it small (128k min).  For large machines
- * we want it large (16MB max).  But it is not linear, because network
+ * we want it large (64MB max).  But it is not linear, because network
  * bandwidth does not increase linearly with machine size.  We use
  *
- *	min_free_kbytes = sqrt(lowmem_kbytes)
+ * 	min_free_kbytes = 4 * sqrt(lowmem_kbytes), for better accuracy:
+ *	min_free_kbytes = sqrt(lowmem_kbytes * 16)
  *
  * which yields
  *
- * 16MB:	128k
- * 32MB:	181k
- * 64MB:	256k
- * 128MB:	362k
- * 256MB:	512k
- * 512MB:	724k
- * 1024MB:	1024k
- * 2048MB:	1448k
- * 4096MB:	2048k
- * 8192MB:	2896k
- * 16384MB:	4096k
+ * 16MB:	512k
+ * 32MB:	724k
+ * 64MB:	1024k
+ * 128MB:	1448k
+ * 256MB:	2048k
+ * 512MB:	2896k
+ * 1024MB:	4096k
+ * 2048MB:	5792k
+ * 4096MB:	8192k
+ * 8192MB:	11584k
+ * 16384MB:	16384k
  */
 static int __init init_per_zone_pages_min(void)
 {
@@ -1980,11 +1985,11 @@
 
 	lowmem_kbytes = nr_free_buffer_pages() * (PAGE_SIZE >> 10);
 
-	min_free_kbytes = int_sqrt(lowmem_kbytes);
+	min_free_kbytes = int_sqrt(lowmem_kbytes * 16);
 	if (min_free_kbytes < 128)
 		min_free_kbytes = 128;
-	if (min_free_kbytes > 16384)
-		min_free_kbytes = 16384;
+	if (min_free_kbytes > 65536)
+		min_free_kbytes = 65536;
 	setup_per_zone_pages_min();
 	setup_per_zone_protection();
 	return 0;