commit 9667a23db0dc0bd4892f0ada7e4e71528eaeed62
author Thomas Gleixner <tglx@linutronix.de> Wed Jul 16 21:04:35 2014 +0000
committer John Stultz <john.stultz@linaro.org> Wed Jul 23 10:18:06 2014 -0700
tree 412d0676a0157467442c4d02e646f8272ccd620e
parent ccbf62d8a284cf181ac28c8e8407dd077d90dd4b

delayacct: Make accounting nanosecond based

Kill the timespec juggling and calculate with plain nanoseconds.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>

kernel/delayacct.c

diff --git a/kernel/delayacct.c b/kernel/delayacct.c
index de699f4..cf2e65d 100644
--- a/kernel/delayacct.c
+++ b/kernel/delayacct.c
@@ -46,32 +46,25 @@
 }
 
 /*
- * Finish delay accounting for a statistic using
- * its timestamps (@start, @end), accumalator (@total) and @count
+ * Finish delay accounting for a statistic using its timestamps (@start),
+ * accumalator (@total) and @count
  */
-
-static void delayacct_end(struct timespec *start, struct timespec *end,
-				u64 *total, u32 *count)
+static void delayacct_end(u64 *start, u64 *total, u32 *count)
 {
-	struct timespec ts;
-	s64 ns;
+	s64 ns = ktime_get_ns() - *start;
 	unsigned long flags;
 
-	ktime_get_ts(end);
-	ts = timespec_sub(*end, *start);
-	ns = timespec_to_ns(&ts);
-	if (ns < 0)
-		return;
-
-	spin_lock_irqsave(&current->delays->lock, flags);
-	*total += ns;
-	(*count)++;
-	spin_unlock_irqrestore(&current->delays->lock, flags);
+	if (ns > 0) {
+		spin_lock_irqsave(&current->delays->lock, flags);
+		*total += ns;
+		(*count)++;
+		spin_unlock_irqrestore(&current->delays->lock, flags);
+	}
 }
 
 void __delayacct_blkio_start(void)
 {
-	ktime_get_ts(&current->delays->blkio_start);
+	current->delays->blkio_start = ktime_get_ns();
 }
 
 void __delayacct_blkio_end(void)
@@ -79,12 +72,10 @@
 	if (current->delays->flags & DELAYACCT_PF_SWAPIN)
 		/* Swapin block I/O */
 		delayacct_end(&current->delays->blkio_start,
-			&current->delays->blkio_end,
 			&current->delays->swapin_delay,
 			&current->delays->swapin_count);
 	else	/* Other block I/O */
 		delayacct_end(&current->delays->blkio_start,
-			&current->delays->blkio_end,
 			&current->delays->blkio_delay,
 			&current->delays->blkio_count);
 }
@@ -159,13 +150,12 @@
 
 void __delayacct_freepages_start(void)
 {
-	ktime_get_ts(&current->delays->freepages_start);
+	current->delays->freepages_start = ktime_get_ns();
 }
 
 void __delayacct_freepages_end(void)
 {
 	delayacct_end(&current->delays->freepages_start,
-			&current->delays->freepages_end,
 			&current->delays->freepages_delay,
 			&current->delays->freepages_count);
 }