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>

1 files changed, 12 insertions, 22 deletions

diff --git a/kernel/delayacct.c b/kernel/delayacct.c
index de699f42f9bc..cf2e65dddb19 100644
--- a/kernel/delayacct.c
+++ b/kernel/delayacct.c
@@ -46,32 +46,25 @@ void __delayacct_tsk_init(struct task_struct *tsk)
 }
 
 /*
- * 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 @@ void __delayacct_blkio_end(void)
         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 @@ __u64 __delayacct_blkio_ticks(struct task_struct *tsk)
 
 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);
 }