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authorMel Gorman <mel@csn.ul.ie>2007-10-16 01:25:54 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-10-16 09:43:00 -0700
commit5adc5be7cd1bcef6bb64f5255d2a33f20a3cf5be (patch)
tree39ed023e8c36cde0c0f9cba50f945e77d3ca26fa /mm
parent9ef9acb05a741ec10a5e9122717736de12adced9 (diff)
Bias the placement of kernel pages at lower PFNs
This patch chooses blocks with lower PFNs when placing kernel allocations. This is particularly important during fallback in low memory situations to stop unmovable pages being placed throughout the entire address space. 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>
Diffstat (limited to 'mm')
-rw-r--r--mm/page_alloc.c20
1 files changed, 20 insertions, 0 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 676aec93d699..e1d87ee1d9c6 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -765,6 +765,23 @@ int move_freepages_block(struct zone *zone, struct page *page, int migratetype)
return move_freepages(zone, start_page, end_page, migratetype);
}
+/* Return the page with the lowest PFN in the list */
+static struct page *min_page(struct list_head *list)
+{
+ unsigned long min_pfn = -1UL;
+ struct page *min_page = NULL, *page;;
+
+ list_for_each_entry(page, list, lru) {
+ unsigned long pfn = page_to_pfn(page);
+ if (pfn < min_pfn) {
+ min_pfn = pfn;
+ min_page = page;
+ }
+ }
+
+ return min_page;
+}
+
/* Remove an element from the buddy allocator from the fallback list */
static struct page *__rmqueue_fallback(struct zone *zone, int order,
int start_migratetype)
@@ -795,8 +812,11 @@ retry:
if (list_empty(&area->free_list[migratetype]))
continue;
+ /* Bias kernel allocations towards low pfns */
page = list_entry(area->free_list[migratetype].next,
struct page, lru);
+ if (unlikely(start_migratetype != MIGRATE_MOVABLE))
+ page = min_page(&area->free_list[migratetype]);
area->nr_free--;
/*