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Subject[PATCH 2/6] mm: vmscan: Scale number of pages reclaimed by reclaim/compaction based on failures
Date
If allocation fails after compaction then compaction may be deferred for
a number of allocation attempts. If there are subsequent failures,
compact_defer_shift is increased to defer for longer periods. This patch
uses that information to scale the number of pages reclaimed with
compact_defer_shift until allocations succeed again.

Signed-off-by: Mel Gorman <mgorman@suse.de>
---
mm/vmscan.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 66e4310..0cb2593 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1708,6 +1708,7 @@ static inline bool should_continue_reclaim(struct lruvec *lruvec,
{
unsigned long pages_for_compaction;
unsigned long inactive_lru_pages;
+ struct zone *zone;

/* If not in reclaim/compaction mode, stop */
if (!in_reclaim_compaction(sc))
@@ -1741,6 +1742,15 @@ static inline bool should_continue_reclaim(struct lruvec *lruvec,
* inactive lists are large enough, continue reclaiming
*/
pages_for_compaction = (2UL << sc->order);
+
+ /*
+ * If compaction is deferred for this order then scale the number of
+ * pages reclaimed based on the number of consecutive allocation
+ * failures
+ */
+ zone = lruvec_zone(lruvec);
+ if (zone->compact_order_failed >= sc->order)
+ pages_for_compaction <<= zone->compact_defer_shift;
inactive_lru_pages = get_lru_size(lruvec, LRU_INACTIVE_FILE);
if (nr_swap_pages > 0)
inactive_lru_pages += get_lru_size(lruvec, LRU_INACTIVE_ANON);
--
1.7.9.2


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