[patch 31/55] delayacct: Make accounting nanosecond based

[Thomas Gleixner]

Kill the timespec juggling and calculate with plain nanoseconds.

Signed-off-by: Thomas Gleixner <t...@linutronix.de>
---
 include/linux/sched.h |    4 ++--
 kernel/delayacct.c    |   34 ++++++++++++----------------------
 2 files changed, 14 insertions(+), 24 deletions(-)

Index: tip/include/linux/sched.h
===================================================================
--- tip.orig/include/linux/sched.h
+++ tip/include/linux/sched.h
@@ -813,7 +813,7 @@ struct task_delay_info {
         * associated with the operation is added to XXX_delay.
         * XXX_delay contains the accumulated delay time in nanoseconds.
         */
-       struct timespec blkio_start, blkio_end; /* Shared by blkio, swapin */
+       u64 blkio_start;        /* Shared by blkio, swapin */
        u64 blkio_delay;        /* wait for sync block io completion */
        u64 swapin_delay;       /* wait for swapin block io completion */
        u32 blkio_count;        /* total count of the number of sync block */
@@ -821,7 +821,7 @@ struct task_delay_info {
        u32 swapin_count;       /* total count of the number of swapin block */
                                /* io operations performed */
 
-       struct timespec freepages_start, freepages_end;
+       u64 freepages_start;
        u64 freepages_delay;    /* wait for memory reclaim */
        u32 freepages_count;    /* total count of memory reclaim */
 };
Index: tip/kernel/delayacct.c
===================================================================
--- tip.orig/kernel/delayacct.c
+++ tip/kernel/delayacct.c
@@ -46,32 +46,25 @@ void __delayacct_tsk_init(struct task_st
 }
 
 /*
- * 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 tas
 
 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);
 }


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