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Subject[PATCH 12/12] Be more agressive about stealing when MIGRATE_RECLAIMABLE allocations fallback
Date

MIGRATE_RECLAIMABLE allocations tend to be very bursty in nature like
when updatedb starts. It is likely this will occur in situations where
MAX_ORDER blocks of pages are not free. This means that updatedb can scatter
MIGRATE_RECLAIMABLE pages throughout the address space. This patch is more
agressive about stealing blocks of pages for MIGRATE_RECLAIMABLE.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
---

page_alloc.c | 18 +++++++++++++++---
1 files changed, 15 insertions(+), 3 deletions(-)

diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.20-mm2-011_biasplacement/mm/page_alloc.c linux-2.6.20-mm2-012_grabbyreclaim/mm/page_alloc.c
--- linux-2.6.20-mm2-011_biasplacement/mm/page_alloc.c 2007-02-20 18:52:18.000000000 +0000
+++ linux-2.6.20-mm2-012_grabbyreclaim/mm/page_alloc.c 2007-02-20 18:54:35.000000000 +0000
@@ -806,11 +806,23 @@ retry:

/*
* If breaking a large block of pages, move all free
- * pages to the preferred allocation list
+ * pages to the preferred allocation list. If falling
+ * back for a reclaimable kernel allocation, be more
+ * agressive about taking ownership of free pages
*/
- if (unlikely(current_order >= MAX_ORDER / 2)) {
+ if (unlikely(current_order >= MAX_ORDER / 2) ||
+ start_migratetype == MIGRATE_RECLAIMABLE) {
+ unsigned long pages;
+ pages = move_freepages_block(zone, page,
+ start_migratetype);
+
+ /* Claim the whole block if over half of it is free */
+ if ((pages << current_order) >= (1 << (MAX_ORDER-2)) &&
+ migratetype != MIGRATE_HIGHATOMIC)
+ set_pageblock_migratetype(page,
+ start_migratetype);
+
migratetype = start_migratetype;
- move_freepages_block(zone, page, migratetype);
}

/* Remove the page from the freelists */
-
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