linux-kernel - [PATCH] LOCKSTAT: patch test - Fix min, max times in /proc/lock

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Date:	Thu, 19 Nov 2009 13:42:06 -0800
From:	Frank Rowand <frank.rowand@...sony.com>
To:	peterz@...radead.org, mingo@...hat.com
CC:	tom.leiming@...il.com, linux-kernel@...r.kernel.org
Subject: [PATCH] LOCKSTAT: patch test - Fix min, max times in /proc/lock_stats

Fix min, max times in /proc/lock_stats

(1) When collecting lock hold and wait times, if the current minimum time is
    zero, it will be replaced by the next time.

(2) When aggregating minimum and maximum lock hold and wait times accross cpus,
    the values are added, instead of selecting the minimum and maximum.


Signed-off-by: Frank Rowand <frank.rowand@...sony.com>

---
 kernel/lockdep.c |   11 	9 +	2 -	0 !
 1 files changed, 9 insertions(+), 2 deletions(-)

Index: linux-2.6/kernel/lockdep.c
===================================================================
--- linux-2.6.orig/kernel/lockdep.c
+++ linux-2.6/kernel/lockdep.c
@@ -168,7 +168,7 @@ static void lock_time_inc(struct lock_ti
 	if (time > lt->max)
 		lt->max = time;
 
-	if (time < lt->min || !lt->min)
+	if (time < lt->min || !lt->nr)
 		lt->min = time;
 
 	lt->total += time;
@@ -177,8 +177,15 @@ static void lock_time_inc(struct lock_ti
 
 static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
 {
-	dst->min += src->min;
-	dst->max += src->max;
+	if (!src->nr)
+		return;
+
+	if (src->max > dst->max)
+		dst->max = src->max;
+
+	if (src->min < dst->min || !dst->nr)
+		dst->min = src->min;
+
 	dst->total += src->total;
 	dst->nr += src->nr;
 }

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