path: root/mm/page_alloc.c
diff options
authorMel Gorman <>2009-09-21 17:02:42 -0700
committerLinus Torvalds <>2009-09-22 07:17:34 -0700
commite0fff1bd12469c45dab088e353d8882761387bb6 (patch)
treedc120a7597bbd4f3841f951346dbe1f7b85dd3fb /mm/page_alloc.c
parent4b4f278c030aa4b6ee0915f396e9a9478d92d610 (diff)
tracing, page-allocator: add trace events for anti-fragmentation falling back to other migratetypes
Fragmentation avoidance depends on being able to use free pages from lists of the appropriate migrate type. In the event this is not possible, __rmqueue_fallback() selects a different list and in some circumstances change the migratetype of the pageblock. Simplistically, the more times this event occurs, the more likely that fragmentation will be a problem later for hugepage allocation at least but there are other considerations such as the order of page being split to satisfy the allocation. This patch adds a trace event for __rmqueue_fallback() that reports what page is being used for the fallback, the orders of relevant pages, the desired migratetype and the migratetype of the lists being used, whether the pageblock changed type and whether this event is important with respect to fragmentation avoidance or not. This information can be used to help analyse fragmentation avoidance and help decide whether min_free_kbytes should be increased or not. Signed-off-by: Mel Gorman <> Acked-by: Rik van Riel <> Reviewed-by: Ingo Molnar <> Cc: Larry Woodman <> Cc: Peter Zijlstra <> Cc: Li Ming Chun <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'mm/page_alloc.c')
1 files changed, 4 insertions, 0 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 80f954d82d7..77f517c18b3 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -853,6 +853,10 @@ __rmqueue_fallback(struct zone *zone, int order, int start_migratetype)
expand(zone, page, order, current_order, area, migratetype);
+ trace_mm_page_alloc_extfrag(page, order, current_order,
+ start_migratetype, migratetype);
return page;