The patch titled
Subject: mm-compaction-create-compact_gap-wrapper-fix
has been added to the -mm tree. Its filename is
mm-compaction-create-compact_gap-wrapper-fix.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-compaction-create-compact_gap-wrapper-fix.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-compaction-create-compact_gap-wrapper-fix.patch
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------------------------------------------------------
From: Vlastimil Babka <vbabka@xxxxxxx>
Subject: mm-compaction-create-compact_gap-wrapper-fix
Clarify the comment of compact_gap() wrt COMPACT_CLUSTER_MAX, per Joonsoo.
Link: http://lkml.kernel.org/r/7b6aed1f-fdf8-2063-9ff4-bbe4de712d37@xxxxxxx
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/compaction.h | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff -puN include/linux/compaction.h~mm-compaction-create-compact_gap-wrapper-fix include/linux/compaction.h
--- a/include/linux/compaction.h~mm-compaction-create-compact_gap-wrapper-fix
+++ a/include/linux/compaction.h
@@ -67,9 +67,16 @@ static inline unsigned long compact_gap(
{
/*
* Although all the isolations for migration are temporary, compaction
- * may have up to 1 << order pages on its list and then try to split
- * an (order - 1) free page. At that point, a gap of 1 << order might
- * not be enough, so it's safer to require twice that amount.
+ * free scanner may have up to 1 << order pages on its list and then
+ * try to split an (order - 1) free page. At that point, a gap of
+ * 1 << order might not be enough, so it's safer to require twice that
+ * amount. Note that the number of pages on the list is also
+ * effectively limited by COMPACT_CLUSTER_MAX, as that's the maximum
+ * that the migrate scanner can have isolated on migrate list, and free
+ * scanner is only invoked when the number of isolated free pages is
+ * lower than that. But it's not worth to complicate the formula here
+ * as a bigger gap for higher orders than strictly necessary can also
+ * improve chances of compaction success.
*/
return 2UL << order;
}
_
Patches currently in -mm which might be from vbabka@xxxxxxx are
mm-compaction-make-whole_zone-flag-ignore-cached-scanner-positions.patch
mm-compaction-cleanup-unused-functions.patch
mm-compaction-rename-compact_partial-to-compact_success.patch
mm-compaction-dont-recheck-watermarks-after-compact_success.patch
mm-compaction-add-the-ultimate-direct-compaction-priority.patch
mm-compaction-more-reliably-increase-direct-compaction-priority.patch
mm-compaction-use-correct-watermark-when-checking-compaction-success.patch
mm-compaction-create-compact_gap-wrapper.patch
mm-compaction-create-compact_gap-wrapper-fix.patch
mm-compaction-use-proper-alloc_flags-in-__compaction_suitable.patch
mm-compaction-require-only-min-watermarks-for-non-costly-orders.patch
mm-compaction-require-only-min-watermarks-for-non-costly-orders-fix.patch
mm-vmscan-make-compaction_ready-more-accurate-and-readable.patch
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