path: root/mm/page_alloc.c
diff options
authorMel Gorman <>2009-09-21 17:02:44 -0700
committerLinus Torvalds <>2009-09-22 07:17:34 -0700
commit0d3d062a6e289e065bd0aa537a6806a1806bf8aa (patch)
tree9895e9cb48674d072885af3424e1ef145ec81f28 /mm/page_alloc.c
parente0fff1bd12469c45dab088e353d8882761387bb6 (diff)
tracing, page-allocator: add trace event for page traffic related to the buddy lists
The page allocation trace event reports that a page was successfully allocated but it does not specify where it came from. When analysing performance, it can be important to distinguish between pages coming from the per-cpu allocator and pages coming from the buddy lists as the latter requires the zone lock to the taken and more data structures to be examined. This patch adds a trace event for __rmqueue reporting when a page is being allocated from the buddy lists. It distinguishes between being called to refill the per-cpu lists or whether it is a high-order allocation. Similarly, this patch adds an event to catch when the PCP lists are being drained a little and pages are going back to the buddy lists. This is trickier to draw conclusions from but high activity on those events could explain why there were a large number of cache misses on a page-allocator-intensive workload. The coalescing and splitting of buddies involves a lot of writing of page metadata and cache line bounces not to mention the acquisition of an interrupt-safe lock necessary to enter this path. [ fix build] Signed-off-by: Mel Gorman <> Acked-by: Rik van Riel <> Reviewed-by: Ingo Molnar <> Cc: Larry Woodman <> Cc: Peter Zijlstra <> Cc: Li Ming Chun <> Reviewed-by: KOSAKI Motohiro <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'mm/page_alloc.c')
1 files changed, 3 insertions, 0 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 77f517c18b3..4c847cc57ca 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -48,6 +48,7 @@
#include <linux/page_cgroup.h>
#include <linux/debugobjects.h>
#include <linux/kmemleak.h>
+#include <trace/events/kmem.h>
#include <asm/tlbflush.h>
#include <asm/div64.h>
@@ -535,6 +536,7 @@ static void free_pages_bulk(struct zone *zone, int count,
page = list_entry(list->prev, struct page, lru);
/* have to delete it as __free_one_page list manipulates */
+ trace_mm_page_pcpu_drain(page, order, page_private(page));
__free_one_page(page, zone, order, page_private(page));
@@ -890,6 +892,7 @@ retry_reserve:
+ trace_mm_page_alloc_zone_locked(page, order, migratetype);
return page;