linux-kernel - [PATCH 5/6] perf: Update sort to handle MAP

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Message-Id: <1395689676-214799-6-git-send-email-dzickus@redhat.com>
Date:	Mon, 24 Mar 2014 15:34:35 -0400
From:	Don Zickus <dzickus@...hat.com>
To:	acme@...stprotocols.net, peterz@...radead.org
Cc:	LKML <linux-kernel@...r.kernel.org>, jolsa@...hat.com,
	jmario@...hat.com, fowles@...each.com, eranian@...gle.com,
	andi.kleen@...el.com, Don Zickus <dzickus@...hat.com>
Subject: [PATCH 5/6] perf: Update sort to handle MAP_SHARED bits

Remove some of the false positives when sorting by utilizing the MAP_SHARED bit.

This helps deal with the COW cases where a virtual address is modified but is
mapped to a read-only shared library area because the perf tool doesn't understand
COW faults.

Using the MAP_SHARED bit tells the tool in this example the memory is private
and will not cause contention with other processes accessing the same shared
library area.

Signed-off-by: Don Zickus <dzickus@...hat.com>
---
 tools/perf/util/sort.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/sort.c b/tools/perf/util/sort.c
index e016fc1..be675f4 100644
--- a/tools/perf/util/sort.c
+++ b/tools/perf/util/sort.c
@@ -1,3 +1,4 @@
+#include <sys/mman.h>
 #include "sort.h"
 #include "hist.h"
 #include "comm.h"
@@ -1001,7 +1002,8 @@ sort__physid_daddr_cmp(struct hist_entry *left, struct hist_entry *right)
 	 * assumed to be unity mapped.  Sort those on address then pid.
 	 */
 
-	if (l_map->maj || l_map->min || l_map->ino || l_map->ino_generation) {
+	if ((l_map->flags & MAP_SHARED) &&
+	   (l_map->maj || l_map->min || l_map->ino || l_map->ino_generation)) {
 		/* mmapped areas */
 
 		if (l_map->maj > r_map->maj) return -1;
-- 
1.7.11.7

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