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

From: Thomas Gleixner
Date: Fri Jul 11 2014 - 09:52:39 EST


Kill the timespec juggling and calculate with plain nanoseconds.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
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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