From e0fff1bd12469c45dab088e353d8882761387bb6 Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Mon, 21 Sep 2009 17:02:42 -0700 Subject: [PATCH] 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 --- include/trace/events/kmem.h | 38 ++++++++++++++++++++++++++++++++++++++ mm/page_alloc.c | 4 ++++ 2 files changed, 42 insertions(+) diff --git a/include/trace/events/kmem.h b/include/trace/events/kmem.h index 0d358a0..aae16ee 100644 --- a/include/trace/events/kmem.h +++ b/include/trace/events/kmem.h @@ -299,6 +299,44 @@ TRACE_EVENT(mm_page_alloc, show_gfp_flags(__entry->gfp_flags)) ); +TRACE_EVENT(mm_page_alloc_extfrag, + + TP_PROTO(struct page *page, + int alloc_order, int fallback_order, + int alloc_migratetype, int fallback_migratetype), + + TP_ARGS(page, + alloc_order, fallback_order, + alloc_migratetype, fallback_migratetype), + + TP_STRUCT__entry( + __field( struct page *, page ) + __field( int, alloc_order ) + __field( int, fallback_order ) + __field( int, alloc_migratetype ) + __field( int, fallback_migratetype ) + ), + + TP_fast_assign( + __entry->page = page; + __entry->alloc_order = alloc_order; + __entry->fallback_order = fallback_order; + __entry->alloc_migratetype = alloc_migratetype; + __entry->fallback_migratetype = fallback_migratetype; + ), + + TP_printk("page=%p pfn=%lu alloc_order=%d fallback_order=%d pageblock_order=%d alloc_migratetype=%d fallback_migratetype=%d fragmenting=%d change_ownership=%d", + __entry->page, + page_to_pfn(__entry->page), + __entry->alloc_order, + __entry->fallback_order, + pageblock_order, + __entry->alloc_migratetype, + __entry->fallback_migratetype, + __entry->fallback_order < pageblock_order, + __entry->alloc_migratetype == __entry->fallback_migratetype) +); + #endif /* _TRACE_KMEM_H */ /* This part must be outside protection */ diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 80f954d..77f517c 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) start_migratetype); expand(zone, page, order, current_order, area, migratetype); + + trace_mm_page_alloc_extfrag(page, order, current_order, + start_migratetype, migratetype); + return page; } } -- 2.7.4