mm, compaction: require only min watermarks for non-costly orders

[linux-2.6-microblaze.git] / mm / compaction.c

diff --git a/mm/compaction.c b/mm/compaction.c
index 658c009..29f6c49 100644 (file)
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1399,10 +1399,14 @@ static enum compact_result __compaction_suitable(struct zone *zone, int order,
         * isolation. We however do use the direct compactor's classzone_idx to
         * skip over zones where lowmem reserves would prevent allocation even
         * if compaction succeeds.
+        * For costly orders, we require low watermark instead of min for
+        * compaction to proceed to increase its chances.
         * ALLOC_CMA is used, as pages in CMA pageblocks are considered
         * suitable migration targets
         */
-       watermark = low_wmark_pages(zone) + compact_gap(order);
+       watermark = (order > PAGE_ALLOC_COSTLY_ORDER) ?
+                               low_wmark_pages(zone) : min_wmark_pages(zone);
+       watermark += compact_gap(order);
        if (!__zone_watermark_ok(zone, 0, watermark, classzone_idx,
                                                ALLOC_CMA, wmark_target))
                return COMPACT_SKIPPED;