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tracing, page-allocator: add trace event for page traffic related to the buddy lists

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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.

[akpm@linux-foundation.org: fix build]
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Ingo Molnar <mingo@elte.hu>
Cc: Larry Woodman <lwoodman@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Li Ming Chun <macli@brc.ubc.ca>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mel Gorman 2009-09-21 17:02:44 -07:00 committed by Linus Torvalds
parent e0fff1bd12
commit 0d3d062a6e
2 changed files with 54 additions and 0 deletions
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51
include/trace/events/kmem.h
View file

@ -299,6 +299,57 @@ TRACE_EVENT(mm_page_alloc,
show_gfp_flags(__entry->gfp_flags))
);
TRACE_EVENT(mm_page_alloc_zone_locked,
TP_PROTO(struct page *page, unsigned int order, int migratetype),
TP_ARGS(page, order, migratetype),
TP_STRUCT__entry(
__field( struct page *, page )
__field( unsigned int, order )
__field( int, migratetype )
),
TP_fast_assign(
__entry->page = page;
__entry->order = order;
__entry->migratetype = migratetype;
),
TP_printk("page=%p pfn=%lu order=%u migratetype=%d percpu_refill=%d",
__entry->page,
page_to_pfn(__entry->page),
__entry->order,
__entry->migratetype,
__entry->order == 0)
);
TRACE_EVENT(mm_page_pcpu_drain,
TP_PROTO(struct page *page, int order, int migratetype),
TP_ARGS(page, order, migratetype),
TP_STRUCT__entry(
__field( struct page *, 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(__entry->page),
__entry->order,
__entry->migratetype)
);
TRACE_EVENT(mm_page_alloc_extfrag,
TP_PROTO(struct page *page,

3
mm/page_alloc.c
View file

@ -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 */
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);
@ -890,6 +892,7 @@ retry_reserve:
}
}
trace_mm_page_alloc_zone_locked(page, order, migratetype);
return page;
}