linux-kernel - [PATCH 14/97] mm: get rid of unnecessary overhead of trace_mm_page_alloc

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Date:	Thu, 28 Aug 2014 19:34:22 +0100
From:	Mel Gorman <mgorman@...e.de>
To:	Jiri Slaby <jslaby@...e.cz>
Cc:	Linux-Stable <stable@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>, Mel Gorman <mgorman@...e.de>
Subject: [PATCH 14/97] mm: get rid of unnecessary overhead of trace_mm_page_alloc_extfrag()

From: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>

commit 52c8f6a5aeb0bdd396849ecaa72d96f8175528f5 upstream.

In general, every tracepoint should be zero overhead if it is disabled.
However, trace_mm_page_alloc_extfrag() is one of exception.  It evaluate
"new_type == start_migratetype" even if tracepoint is disabled.

However, the code can be moved into tracepoint's TP_fast_assign() and
TP_fast_assign exist exactly such purpose.  This patch does it.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Acked-by: Mel Gorman <mgorman@...e.de>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Mel Gorman <mgorman@...e.de>
---
 include/trace/events/kmem.h | 10 ++++------
 mm/page_alloc.c             |  5 ++---
 2 files changed, 6 insertions(+), 9 deletions(-)

diff --git a/include/trace/events/kmem.h b/include/trace/events/kmem.h
index d0c6134..aece134 100644
--- a/include/trace/events/kmem.h
+++ b/include/trace/events/kmem.h
@@ -267,14 +267,12 @@ DEFINE_EVENT_PRINT(mm_page, mm_page_pcpu_drain,
 TRACE_EVENT(mm_page_alloc_extfrag,
 
 	TP_PROTO(struct page *page,
-			int alloc_order, int fallback_order,
-			int alloc_migratetype, int fallback_migratetype,
-			int change_ownership),
+		int alloc_order, int fallback_order,
+		int alloc_migratetype, int fallback_migratetype, int new_migratetype),
 
 	TP_ARGS(page,
 		alloc_order, fallback_order,
-		alloc_migratetype, fallback_migratetype,
-		change_ownership),
+		alloc_migratetype, fallback_migratetype, new_migratetype),
 
 	TP_STRUCT__entry(
 		__field(	struct page *,	page			)
@@ -291,7 +289,7 @@ TRACE_EVENT(mm_page_alloc_extfrag,
 		__entry->fallback_order		= fallback_order;
 		__entry->alloc_migratetype	= alloc_migratetype;
 		__entry->fallback_migratetype	= fallback_migratetype;
-		__entry->change_ownership	= change_ownership;
+		__entry->change_ownership	= (new_migratetype == alloc_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",
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 8b010ca..e285eac 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1118,9 +1118,8 @@ __rmqueue_fallback(struct zone *zone, int order, int start_migratetype)
 			       is_migrate_cma(migratetype)
 			     ? migratetype : start_migratetype);
 
-			trace_mm_page_alloc_extfrag(page, order,
-				current_order, start_migratetype, migratetype,
-				new_type == start_migratetype);
+			trace_mm_page_alloc_extfrag(page, order, current_order,
+				start_migratetype, migratetype, new_type);
 
 			return page;
 		}
-- 
1.8.4.5

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