[PATCH] Avoid excessive sorting of early_node_map[]
find_min_pfn_for_node() and find_min_pfn_with_active_regions() sort
early_node_map[] on every call. This is an excessive amount of sorting and
that can be avoided. This patch always searches the whole early_node_map[]
in find_min_pfn_for_node() instead of returning the first value found. The
map is then only sorted once when required. Successfully boot tested on a
number of machines.
[akpm@osdl.org: cleanup]
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index f12052d..f26fdc9 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2877,20 +2877,23 @@
cmp_node_active_region, NULL);
}
-/* Find the lowest pfn for a node. This depends on a sorted early_node_map */
+/* Find the lowest pfn for a node */
unsigned long __init find_min_pfn_for_node(unsigned long nid)
{
int i;
-
- /* Regions in the early_node_map can be in any order */
- sort_node_map();
+ unsigned long min_pfn = ULONG_MAX;
/* Assuming a sorted map, the first range found has the starting pfn */
for_each_active_range_index_in_nid(i, nid)
- return early_node_map[i].start_pfn;
+ min_pfn = min(min_pfn, early_node_map[i].start_pfn);
- printk(KERN_WARNING "Could not find start_pfn for node %lu\n", nid);
- return 0;
+ if (min_pfn == ULONG_MAX) {
+ printk(KERN_WARNING
+ "Could not find start_pfn for node %lu\n", nid);
+ return 0;
+ }
+
+ return min_pfn;
}
/**
@@ -2939,6 +2942,9 @@
unsigned long nid;
enum zone_type i;
+ /* Sort early_node_map as initialisation assumes it is sorted */
+ sort_node_map();
+
/* Record where the zone boundaries are */
memset(arch_zone_lowest_possible_pfn, 0,
sizeof(arch_zone_lowest_possible_pfn));