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);