path: root/mm
diff options
authorMel Gorman <mel@csn.ul.ie>2007-12-17 16:20:05 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-12-17 19:28:16 -0800
commit81eabcbe0b991ddef5216f30ae91c4b226d54b6d (patch)
treef444d157d56583e034d3384a0102b5cb22d08743 /mm
parentapm_event{,info}_t are userspace types (diff)
mm: fix page allocation for larger I/O segments
In some cases the IO subsystem is able to merge requests if the pages are adjacent in physical memory. This was achieved in the allocator by having expand() return pages in physically contiguous order in situations were a large buddy was split. However, list-based anti-fragmentation changed the order pages were returned in to avoid searching in buffered_rmqueue() for a page of the appropriate migrate type. This patch restores behaviour of rmqueue_bulk() preserving the physical order of pages returned by the allocator without incurring increased search costs for anti-fragmentation. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Cc: James Bottomley <James.Bottomley@steeleye.com> Cc: Jens Axboe <jens.axboe@oracle.com> Cc: Mark Lord <mlord@pobox.com Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
1 files changed, 11 insertions, 0 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b5a58d476c1a..d73bfad1c32f 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -847,8 +847,19 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order,
struct page *page = __rmqueue(zone, order, migratetype);
if (unlikely(page == NULL))
+ /*
+ * Split buddy pages returned by expand() are received here
+ * in physical page order. The page is added to the callers and
+ * list and the list head then moves forward. From the callers
+ * perspective, the linked list is ordered by page number in
+ * some conditions. This is useful for IO devices that can
+ * merge IO requests if the physical pages are ordered
+ * properly.
+ */
list_add(&page->lru, list);
set_page_private(page, migratetype);
+ list = &page->lru;
return i;