Page allocator: get rid of the list of cold pages

We have repeatedly discussed if the cold pages still have a point. There is
one way to join the two lists: Use a single list and put the cold pages at the
end and the hot pages at the beginning. That way a single list can serve for
both types of allocations.

The discussion of the RFC for this and Mel's measurements indicate that
there may not be too much of a point left to having separate lists for
hot and cold pages (see http://marc.info/?t=119492914200001&r=1&w=2).

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Martin Bligh <mbligh@mbligh.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 12 insertions, 18 deletions

diff --git a/mm/vmstat.c b/mm/vmstat.c
index 9ffc573ceb6e..888668e0b7db 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -337,7 +337,7 @@ void refresh_cpu_vm_stats(int cpu)
 		 * Check if there are pages remaining in this pageset
 		 * if not then there is nothing to expire.
 		 */
-		if (!p->expire || (!p->pcp[0].count && !p->pcp[1].count))
+		if (!p->expire || !p->pcp.count)
 			continue;
 
 		/*
@@ -352,11 +352,8 @@ void refresh_cpu_vm_stats(int cpu)
 		if (p->expire)
 			continue;
 
-		if (p->pcp[0].count)
-			drain_zone_pages(zone, p->pcp + 0);
-
-		if (p->pcp[1].count)
-			drain_zone_pages(zone, p->pcp + 1);
+		if (p->pcp.count)
+			drain_zone_pages(zone, &p->pcp);
 #endif
 	}
 
@@ -693,20 +690,17 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
 		   "\n  pagesets");
 	for_each_online_cpu(i) {
 		struct per_cpu_pageset *pageset;
-		int j;
 
 		pageset = zone_pcp(zone, i);
-		for (j = 0; j < ARRAY_SIZE(pageset->pcp); j++) {
-			seq_printf(m,
-				   "\n    cpu: %i pcp: %i"
-				   "\n              count: %i"
-				   "\n              high:  %i"
-				   "\n              batch: %i",
-				   i, j,
-				   pageset->pcp[j].count,
-				   pageset->pcp[j].high,
-				   pageset->pcp[j].batch);
-			}
+		seq_printf(m,
+			   "\n    cpu: %i"
+			   "\n              count: %i"
+			   "\n              high:  %i"
+			   "\n              batch: %i",
+			   i,
+			   pageset->pcp.count,
+			   pageset->pcp.high,
+			   pageset->pcp.batch);
 #ifdef CONFIG_SMP
 		seq_printf(m, "\n  vm stats threshold: %d",
 				pageset->stat_threshold);