Messages in this thread Patch in this message | | | From | Mel Gorman <> | Subject | [PATCH 3/4] tracing, page-allocator: Add trace event for page traffic related to the buddy lists | Date | Wed, 29 Jul 2009 22:05:50 +0100 |
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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.
Signed-off-by: Mel Gorman <mel@csn.ul.ie> --- include/trace/events/kmem.h | 54 +++++++++++++++++++++++++++++++++++++++++++ mm/page_alloc.c | 2 + 2 files changed, 56 insertions(+), 0 deletions(-)
diff --git a/include/trace/events/kmem.h b/include/trace/events/kmem.h index 0b4002e..3be3df3 100644 --- a/include/trace/events/kmem.h +++ b/include/trace/events/kmem.h @@ -311,6 +311,60 @@ TRACE_EVENT(mm_page_alloc, show_gfp_flags(__entry->gfp_flags)) ); +TRACE_EVENT(mm_page_alloc_zone_locked, + + TP_PROTO(const void *page, unsigned int order, + int migratetype, int percpu_refill), + + TP_ARGS(page, order, migratetype, percpu_refill), + + TP_STRUCT__entry( + __field( const void *, page ) + __field( unsigned int, order ) + __field( int, migratetype ) + __field( int, percpu_refill ) + ), + + TP_fast_assign( + __entry->page = page; + __entry->order = order; + __entry->migratetype = migratetype; + __entry->percpu_refill = percpu_refill; + ), + + TP_printk("page=%p pfn=%lu order=%u migratetype=%d percpu_refill=%d", + __entry->page, + page_to_pfn((struct page *)__entry->page), + __entry->order, + __entry->migratetype, + __entry->percpu_refill) +); + +TRACE_EVENT(mm_page_pcpu_drain, + + TP_PROTO(const void *page, int order, int migratetype), + + TP_ARGS(page, order, migratetype), + + TP_STRUCT__entry( + __field( const void *, page ) + __field( int, order ) + __field( int, migratetype ) + ), + + TP_fast_assign( + __entry->page = page; + __entry->order = order; + __entry->migratetype = migratetype; + ), + + TP_printk("page=%p pfn=%lu order=%d migratetype=%d", + __entry->page, + page_to_pfn((struct page *)__entry->page), + __entry->order, + __entry->migratetype) +); + TRACE_EVENT(mm_page_alloc_extfrag, TP_PROTO(const void *page, diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 8113403..1bcef16 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -535,6 +535,7 @@ 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 */ list_del(&page->lru); + trace_mm_page_pcpu_drain(page, order, page_private(page)); __free_one_page(page, zone, order, page_private(page)); } spin_unlock(&zone->lock); @@ -878,6 +879,7 @@ retry_reserve: } } + trace_mm_page_alloc_zone_locked(page, order, migratetype, order == 0); return page; } -- 1.6.3.3
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