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authorMel Gorman <mel@csn.ul.ie>2009-07-29 15:02:04 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-07-29 19:10:34 -0700
commite084b2d95e48b31aa45f9c49ffc6cdae8bdb21d4 (patch)
treeff15d36a3a1e49fdbd5080decb7ab00afdd60099 /mm/page_alloc.c
parent51fbb4bab6c8710eb897ab3fb06efbbc921f3a8d (diff)
downloadconfigs-e084b2d95e48b31aa45f9c49ffc6cdae8bdb21d4.tar.gz
page-allocator: preserve PFN ordering when __GFP_COLD is set
Fix a post-2.6.24 performace regression caused by 3dfa5721f12c3d5a441448086bee156887daa961 ("page-allocator: preserve PFN ordering when __GFP_COLD is set"). Narayanan reports "The regression is around 15%. There is no disk controller as our setup is based on Samsung OneNAND used as a memory mapped device on a OMAP2430 based board." The page allocator tries to preserve contiguous PFN ordering when returning pages such that repeated callers to the allocator have a strong chance of getting physically contiguous pages, particularly when external fragmentation is low. However, of the bulk of the allocations have __GFP_COLD set as they are due to aio_read() for example, then the PFNs are in reverse PFN order. This can cause performance degration when used with IO controllers that could have merged the requests. This patch attempts to preserve the contiguous ordering of PFNs for users of __GFP_COLD. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reported-by: Narayananu Gopalakrishnan <narayanan.g@samsung.com> Tested-by: Narayanan Gopalakrishnan <narayanan.g@samsung.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/page_alloc.c')
-rw-r--r--mm/page_alloc.c13
1 files changed, 9 insertions, 4 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index caa92689aac..ae28c22a7fd 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -882,7 +882,7 @@ retry_reserve:
*/
static int rmqueue_bulk(struct zone *zone, unsigned int order,
unsigned long count, struct list_head *list,
- int migratetype)
+ int migratetype, int cold)
{
int i;
@@ -901,7 +901,10 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order,
* merge IO requests if the physical pages are ordered
* properly.
*/
- list_add(&page->lru, list);
+ if (likely(cold == 0))
+ list_add(&page->lru, list);
+ else
+ list_add_tail(&page->lru, list);
set_page_private(page, migratetype);
list = &page->lru;
}
@@ -1119,7 +1122,8 @@ again:
local_irq_save(flags);
if (!pcp->count) {
pcp->count = rmqueue_bulk(zone, 0,
- pcp->batch, &pcp->list, migratetype);
+ pcp->batch, &pcp->list,
+ migratetype, cold);
if (unlikely(!pcp->count))
goto failed;
}
@@ -1138,7 +1142,8 @@ again:
/* Allocate more to the pcp list if necessary */
if (unlikely(&page->lru == &pcp->list)) {
pcp->count += rmqueue_bulk(zone, 0,
- pcp->batch, &pcp->list, migratetype);
+ pcp->batch, &pcp->list,
+ migratetype, cold);
page = list_entry(pcp->list.next, struct page, lru);
}