* [PATCH/Resend] timer stats: add quick check to avoid function calls
@ 2009-06-23 14:12 Heiko Carstens
2009-06-23 15:08 ` Ingo Molnar
0 siblings, 1 reply; 4+ messages in thread
From: Heiko Carstens @ 2009-06-23 14:12 UTC (permalink / raw)
To: Thomas Gleixner, Andrew Morton
Cc: Martin Schwidefsky, Mustafa Mesanovic, Arjan van de Ven,
Ingo Molnar, linux-kernel
From: Heiko Carstens <heiko.carstens@de.ibm.com>
When the kernel is configured with CONFIG_TIMER_STATS but timer stats
are runtime disabled we still get calls to __timer_stats_timer_set_start_info
which initializes some fields in the corresponding struct timer_list.
So add some quick checks in the the timer stats setup functions to avoid
function calls to __timer_stats_timer_set_start_info when timer stats are
disabled.
In an artificial workload that does nothing but playing ping pong with a
single tcp packet via loopback this decreases cpu consumption by 1 - 1.5%.
This is part of a modified function trace output on SLES11:
perl-2497 [00] 28630647177732388 [+ 125]: sk_reset_timer <-tcp_v4_rcv
perl-2497 [00] 28630647177732513 [+ 125]: mod_timer <-sk_reset_timer
perl-2497 [00] 28630647177732638 [+ 125]: __timer_stats_timer_set_start_info <-mod_timer
perl-2497 [00] 28630647177732763 [+ 125]: __mod_timer <-mod_timer
perl-2497 [00] 28630647177732888 [+ 125]: __timer_stats_timer_set_start_info <-__mod_timer
perl-2497 [00] 28630647177733013 [+ 93]: lock_timer_base <-__mod_timer
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
---
include/linux/hrtimer.h | 6 ++++++
include/linux/timer.h | 4 ++++
kernel/time/timer_stats.c | 16 ++++++++--------
kernel/timer.c | 2 ++
4 files changed, 20 insertions(+), 8 deletions(-)
Index: linux-2.6/include/linux/hrtimer.h
===================================================================
--- linux-2.6.orig/include/linux/hrtimer.h
+++ linux-2.6/include/linux/hrtimer.h
@@ -438,12 +438,16 @@ extern void sysrq_timer_list_show(void);
*/
#ifdef CONFIG_TIMER_STATS
+extern int timer_stats_active;
+
extern void timer_stats_update_stats(void *timer, pid_t pid, void *startf,
void *timerf, char *comm,
unsigned int timer_flag);
static inline void timer_stats_account_hrtimer(struct hrtimer *timer)
{
+ if (likely(!timer->start_pid))
+ return;
timer_stats_update_stats(timer, timer->start_pid, timer->start_site,
timer->function, timer->start_comm, 0);
}
@@ -453,6 +457,8 @@ extern void __timer_stats_hrtimer_set_st
static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer)
{
+ if (likely(!timer_stats_active))
+ return;
__timer_stats_hrtimer_set_start_info(timer, __builtin_return_address(0));
}
Index: linux-2.6/include/linux/timer.h
===================================================================
--- linux-2.6.orig/include/linux/timer.h
+++ linux-2.6/include/linux/timer.h
@@ -187,6 +187,8 @@ extern unsigned long get_next_timer_inte
*/
#ifdef CONFIG_TIMER_STATS
+extern int timer_stats_active;
+
#define TIMER_STATS_FLAG_DEFERRABLE 0x1
extern void init_timer_stats(void);
@@ -200,6 +202,8 @@ extern void __timer_stats_timer_set_star
static inline void timer_stats_timer_set_start_info(struct timer_list *timer)
{
+ if (likely(!timer_stats_active))
+ return;
__timer_stats_timer_set_start_info(timer, __builtin_return_address(0));
}
Index: linux-2.6/kernel/timer.c
===================================================================
--- linux-2.6.orig/kernel/timer.c
+++ linux-2.6/kernel/timer.c
@@ -378,6 +378,8 @@ static void timer_stats_account_timer(st
{
unsigned int flag = 0;
+ if (likely(!timer->start_site))
+ return;
if (unlikely(tbase_get_deferrable(timer->base)))
flag |= TIMER_STATS_FLAG_DEFERRABLE;
Index: linux-2.6/kernel/time/timer_stats.c
===================================================================
--- linux-2.6.orig/kernel/time/timer_stats.c
+++ linux-2.6/kernel/time/timer_stats.c
@@ -96,7 +96,7 @@ static DEFINE_MUTEX(show_mutex);
/*
* Collection status, active/inactive:
*/
-static int __read_mostly active;
+int __read_mostly timer_stats_active;
/*
* Beginning/end timestamps of measurement:
@@ -242,7 +242,7 @@ void timer_stats_update_stats(void *time
struct entry *entry, input;
unsigned long flags;
- if (likely(!active))
+ if (likely(!timer_stats_active))
return;
lock = &per_cpu(lookup_lock, raw_smp_processor_id());
@@ -254,7 +254,7 @@ void timer_stats_update_stats(void *time
input.timer_flag = timer_flag;
spin_lock_irqsave(lock, flags);
- if (!active)
+ if (!timer_stats_active)
goto out_unlock;
entry = tstat_lookup(&input, comm);
@@ -290,7 +290,7 @@ static int tstats_show(struct seq_file *
/*
* If still active then calculate up to now:
*/
- if (active)
+ if (timer_stats_active)
time_stop = ktime_get();
time = ktime_sub(time_stop, time_start);
@@ -368,18 +368,18 @@ static ssize_t tstats_write(struct file
mutex_lock(&show_mutex);
switch (ctl[0]) {
case '0':
- if (active) {
- active = 0;
+ if (timer_stats_active) {
+ timer_stats_active = 0;
time_stop = ktime_get();
sync_access();
}
break;
case '1':
- if (!active) {
+ if (!timer_stats_active) {
reset_entries();
time_start = ktime_get();
smp_mb();
- active = 1;
+ timer_stats_active = 1;
}
break;
default:
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH/Resend] timer stats: add quick check to avoid function calls
2009-06-23 14:12 [PATCH/Resend] timer stats: add quick check to avoid function calls Heiko Carstens
@ 2009-06-23 15:08 ` Ingo Molnar
2009-06-23 15:38 ` Heiko Carstens
0 siblings, 1 reply; 4+ messages in thread
From: Ingo Molnar @ 2009-06-23 15:08 UTC (permalink / raw)
To: Heiko Carstens
Cc: Thomas Gleixner, Andrew Morton, Martin Schwidefsky,
Mustafa Mesanovic, Arjan van de Ven, linux-kernel
* Heiko Carstens <heiko.carstens@de.ibm.com> wrote:
> From: Heiko Carstens <heiko.carstens@de.ibm.com>
>
> When the kernel is configured with CONFIG_TIMER_STATS but timer stats
> are runtime disabled we still get calls to __timer_stats_timer_set_start_info
> which initializes some fields in the corresponding struct timer_list.
>
> So add some quick checks in the the timer stats setup functions to avoid
> function calls to __timer_stats_timer_set_start_info when timer stats are
> disabled.
>
> In an artificial workload that does nothing but playing ping pong with a
> single tcp packet via loopback this decreases cpu consumption by 1 - 1.5%.
>
> This is part of a modified function trace output on SLES11:
>
> perl-2497 [00] 28630647177732388 [+ 125]: sk_reset_timer <-tcp_v4_rcv
> perl-2497 [00] 28630647177732513 [+ 125]: mod_timer <-sk_reset_timer
> perl-2497 [00] 28630647177732638 [+ 125]: __timer_stats_timer_set_start_info <-mod_timer
> perl-2497 [00] 28630647177732763 [+ 125]: __mod_timer <-mod_timer
> perl-2497 [00] 28630647177732888 [+ 125]: __timer_stats_timer_set_start_info <-__mod_timer
> perl-2497 [00] 28630647177733013 [+ 93]: lock_timer_base <-__mod_timer
makes sense.
Only one very small detail:
>
> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
> ---
>
> include/linux/hrtimer.h | 6 ++++++
> include/linux/timer.h | 4 ++++
> kernel/time/timer_stats.c | 16 ++++++++--------
> kernel/timer.c | 2 ++
> 4 files changed, 20 insertions(+), 8 deletions(-)
>
> Index: linux-2.6/include/linux/hrtimer.h
> ===================================================================
> --- linux-2.6.orig/include/linux/hrtimer.h
> +++ linux-2.6/include/linux/hrtimer.h
> @@ -438,12 +438,16 @@ extern void sysrq_timer_list_show(void);
> */
> #ifdef CONFIG_TIMER_STATS
>
> +extern int timer_stats_active;
> +
> extern void timer_stats_update_stats(void *timer, pid_t pid, void *startf,
> void *timerf, char *comm,
> unsigned int timer_flag);
>
> static inline void timer_stats_account_hrtimer(struct hrtimer *timer)
> {
> + if (likely(!timer->start_pid))
> + return;
> timer_stats_update_stats(timer, timer->start_pid, timer->start_site,
> timer->function, timer->start_comm, 0);
> }
> @@ -453,6 +457,8 @@ extern void __timer_stats_hrtimer_set_st
>
> static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer)
> {
> + if (likely(!timer_stats_active))
> + return;
> __timer_stats_hrtimer_set_start_info(timer, __builtin_return_address(0));
> }
>
> Index: linux-2.6/include/linux/timer.h
> ===================================================================
> --- linux-2.6.orig/include/linux/timer.h
> +++ linux-2.6/include/linux/timer.h
> @@ -187,6 +187,8 @@ extern unsigned long get_next_timer_inte
> */
> #ifdef CONFIG_TIMER_STATS
>
> +extern int timer_stats_active;
Why is this declared twice, once in hrtimer.h and once in timer.h?
One should suffice, right?
Ingo
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH/Resend] timer stats: add quick check to avoid function calls
2009-06-23 15:08 ` Ingo Molnar
@ 2009-06-23 15:38 ` Heiko Carstens
2009-06-24 9:47 ` [tip:timers/urgent] timer stats: Optimize by adding " tip-bot for Heiko Carstens
0 siblings, 1 reply; 4+ messages in thread
From: Heiko Carstens @ 2009-06-23 15:38 UTC (permalink / raw)
To: Ingo Molnar
Cc: Thomas Gleixner, Andrew Morton, Martin Schwidefsky,
Mustafa Mesanovic, Arjan van de Ven, linux-kernel
On Tue, Jun 23, 2009 at 05:08:03PM +0200, Ingo Molnar wrote:
>
> * Heiko Carstens <heiko.carstens@de.ibm.com> wrote:
>
> > From: Heiko Carstens <heiko.carstens@de.ibm.com>
> >
> > When the kernel is configured with CONFIG_TIMER_STATS but timer stats
> > are runtime disabled we still get calls to __timer_stats_timer_set_start_info
> > which initializes some fields in the corresponding struct timer_list.
> >
> > So add some quick checks in the the timer stats setup functions to avoid
> > function calls to __timer_stats_timer_set_start_info when timer stats are
> > disabled.
> >
> > In an artificial workload that does nothing but playing ping pong with a
> > single tcp packet via loopback this decreases cpu consumption by 1 - 1.5%.
> >
> > This is part of a modified function trace output on SLES11:
> >
> > perl-2497 [00] 28630647177732388 [+ 125]: sk_reset_timer <-tcp_v4_rcv
> > perl-2497 [00] 28630647177732513 [+ 125]: mod_timer <-sk_reset_timer
> > perl-2497 [00] 28630647177732638 [+ 125]: __timer_stats_timer_set_start_info <-mod_timer
> > perl-2497 [00] 28630647177732763 [+ 125]: __mod_timer <-mod_timer
> > perl-2497 [00] 28630647177732888 [+ 125]: __timer_stats_timer_set_start_info <-__mod_timer
> > perl-2497 [00] 28630647177733013 [+ 93]: lock_timer_base <-__mod_timer
>
> makes sense.
>
> Only one very small detail:
[..]
> > Index: linux-2.6/include/linux/timer.h
> > ===================================================================
> > --- linux-2.6.orig/include/linux/timer.h
> > +++ linux-2.6/include/linux/timer.h
> > @@ -187,6 +187,8 @@ extern unsigned long get_next_timer_inte
> > */
> > #ifdef CONFIG_TIMER_STATS
> >
> > +extern int timer_stats_active;
>
> Why is this declared twice, once in hrtimer.h and once in timer.h?
> One should suffice, right?
Actually I only followed the example of timer_stats_update_stats()
which is declared also in both files.
But including timer.h from hrtimer.h doesn't bring up any compile
breakages on the few configs I tested.
Updated patch which avoids the double declaration but adds an
include of timer.h to hrtimer.h
Subject: [PATCH] timer stats: add quick check to avoid function calls
From: Heiko Carstens <heiko.carstens@de.ibm.com>
When the kernel is configured with CONFIG_TIMER_STATS but timer stats
are runtime disabled we still get calls to __timer_stats_timer_set_start_info
which initializes some fields in the corresponding struct timer_list.
So add some quick checks in the the timer stats setup functions to avoid
function calls to __timer_stats_timer_set_start_info when timer stats are
disabled.
In an artificial workload that does nothing but playing ping pong with a
single tcp packet via loopback this decreases cpu consumption by 1 - 1.5%.
This is part of a modified function trace output on SLES11:
perl-2497 [00] 28630647177732388 [+ 125]: sk_reset_timer <-tcp_v4_rcv
perl-2497 [00] 28630647177732513 [+ 125]: mod_timer <-sk_reset_timer
perl-2497 [00] 28630647177732638 [+ 125]: __timer_stats_timer_set_start_info <-mod_timer
perl-2497 [00] 28630647177732763 [+ 125]: __mod_timer <-mod_timer
perl-2497 [00] 28630647177732888 [+ 125]: __timer_stats_timer_set_start_info <-__mod_timer
perl-2497 [00] 28630647177733013 [+ 93]: lock_timer_base <-__mod_timer
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
---
include/linux/hrtimer.h | 5 +++++
include/linux/timer.h | 4 ++++
kernel/time/timer_stats.c | 16 ++++++++--------
kernel/timer.c | 2 ++
4 files changed, 19 insertions(+), 8 deletions(-)
Index: linux-2.6/include/linux/hrtimer.h
===================================================================
--- linux-2.6.orig/include/linux/hrtimer.h
+++ linux-2.6/include/linux/hrtimer.h
@@ -21,6 +21,7 @@
#include <linux/list.h>
#include <linux/wait.h>
#include <linux/percpu.h>
+#include <linux/timer.h>
struct hrtimer_clock_base;
@@ -447,6 +448,8 @@ extern void timer_stats_update_stats(voi
static inline void timer_stats_account_hrtimer(struct hrtimer *timer)
{
+ if (likely(!timer->start_pid))
+ return;
timer_stats_update_stats(timer, timer->start_pid, timer->start_site,
timer->function, timer->start_comm, 0);
}
@@ -456,6 +459,8 @@ extern void __timer_stats_hrtimer_set_st
static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer)
{
+ if (likely(!timer_stats_active))
+ return;
__timer_stats_hrtimer_set_start_info(timer, __builtin_return_address(0));
}
Index: linux-2.6/include/linux/timer.h
===================================================================
--- linux-2.6.orig/include/linux/timer.h
+++ linux-2.6/include/linux/timer.h
@@ -190,6 +190,8 @@ extern unsigned long get_next_timer_inte
*/
#ifdef CONFIG_TIMER_STATS
+extern int timer_stats_active;
+
#define TIMER_STATS_FLAG_DEFERRABLE 0x1
extern void init_timer_stats(void);
@@ -203,6 +205,8 @@ extern void __timer_stats_timer_set_star
static inline void timer_stats_timer_set_start_info(struct timer_list *timer)
{
+ if (likely(!timer_stats_active))
+ return;
__timer_stats_timer_set_start_info(timer, __builtin_return_address(0));
}
Index: linux-2.6/kernel/timer.c
===================================================================
--- linux-2.6.orig/kernel/timer.c
+++ linux-2.6/kernel/timer.c
@@ -380,6 +380,8 @@ static void timer_stats_account_timer(st
{
unsigned int flag = 0;
+ if (likely(!timer->start_site))
+ return;
if (unlikely(tbase_get_deferrable(timer->base)))
flag |= TIMER_STATS_FLAG_DEFERRABLE;
Index: linux-2.6/kernel/time/timer_stats.c
===================================================================
--- linux-2.6.orig/kernel/time/timer_stats.c
+++ linux-2.6/kernel/time/timer_stats.c
@@ -96,7 +96,7 @@ static DEFINE_MUTEX(show_mutex);
/*
* Collection status, active/inactive:
*/
-static int __read_mostly active;
+int __read_mostly timer_stats_active;
/*
* Beginning/end timestamps of measurement:
@@ -242,7 +242,7 @@ void timer_stats_update_stats(void *time
struct entry *entry, input;
unsigned long flags;
- if (likely(!active))
+ if (likely(!timer_stats_active))
return;
lock = &per_cpu(lookup_lock, raw_smp_processor_id());
@@ -254,7 +254,7 @@ void timer_stats_update_stats(void *time
input.timer_flag = timer_flag;
spin_lock_irqsave(lock, flags);
- if (!active)
+ if (!timer_stats_active)
goto out_unlock;
entry = tstat_lookup(&input, comm);
@@ -290,7 +290,7 @@ static int tstats_show(struct seq_file *
/*
* If still active then calculate up to now:
*/
- if (active)
+ if (timer_stats_active)
time_stop = ktime_get();
time = ktime_sub(time_stop, time_start);
@@ -368,18 +368,18 @@ static ssize_t tstats_write(struct file
mutex_lock(&show_mutex);
switch (ctl[0]) {
case '0':
- if (active) {
- active = 0;
+ if (timer_stats_active) {
+ timer_stats_active = 0;
time_stop = ktime_get();
sync_access();
}
break;
case '1':
- if (!active) {
+ if (!timer_stats_active) {
reset_entries();
time_start = ktime_get();
smp_mb();
- active = 1;
+ timer_stats_active = 1;
}
break;
default:
^ permalink raw reply [flat|nested] 4+ messages in thread
* [tip:timers/urgent] timer stats: Optimize by adding quick check to avoid function calls
2009-06-23 15:38 ` Heiko Carstens
@ 2009-06-24 9:47 ` tip-bot for Heiko Carstens
0 siblings, 0 replies; 4+ messages in thread
From: tip-bot for Heiko Carstens @ 2009-06-24 9:47 UTC (permalink / raw)
To: linux-tip-commits
Cc: linux-kernel, hpa, mingo, schwidefsky, arjan, akpm,
mustafa.mesanovic, heiko.carstens, tglx, mingo
Commit-ID: 507e123151149e578c9aae33eb876c49824da5f8
Gitweb: http://git.kernel.org/tip/507e123151149e578c9aae33eb876c49824da5f8
Author: Heiko Carstens <heiko.carstens@de.ibm.com>
AuthorDate: Tue, 23 Jun 2009 17:38:15 +0200
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 24 Jun 2009 11:15:09 +0200
timer stats: Optimize by adding quick check to avoid function calls
When the kernel is configured with CONFIG_TIMER_STATS but timer
stats are runtime disabled we still get calls to
__timer_stats_timer_set_start_info which initializes some
fields in the corresponding struct timer_list.
So add some quick checks in the the timer stats setup functions
to avoid function calls to __timer_stats_timer_set_start_info
when timer stats are disabled.
In an artificial workload that does nothing but playing ping
pong with a single tcp packet via loopback this decreases cpu
consumption by 1 - 1.5%.
This is part of a modified function trace output on SLES11:
perl-2497 [00] 28630647177732388 [+ 125]: sk_reset_timer <-tcp_v4_rcv
perl-2497 [00] 28630647177732513 [+ 125]: mod_timer <-sk_reset_timer
perl-2497 [00] 28630647177732638 [+ 125]: __timer_stats_timer_set_start_info <-mod_timer
perl-2497 [00] 28630647177732763 [+ 125]: __mod_timer <-mod_timer
perl-2497 [00] 28630647177732888 [+ 125]: __timer_stats_timer_set_start_info <-__mod_timer
perl-2497 [00] 28630647177733013 [+ 93]: lock_timer_base <-__mod_timer
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Mustafa Mesanovic <mustafa.mesanovic@de.ibm.com>
Cc: Arjan van de Ven <arjan@infradead.org>
LKML-Reference: <20090623153811.GA4641@osiris.boeblingen.de.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
include/linux/hrtimer.h | 5 +++++
include/linux/timer.h | 4 ++++
kernel/time/timer_stats.c | 16 ++++++++--------
kernel/timer.c | 2 ++
4 files changed, 19 insertions(+), 8 deletions(-)
diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index 7400900..54648e6 100644
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -21,6 +21,7 @@
#include <linux/list.h>
#include <linux/wait.h>
#include <linux/percpu.h>
+#include <linux/timer.h>
struct hrtimer_clock_base;
@@ -447,6 +448,8 @@ extern void timer_stats_update_stats(void *timer, pid_t pid, void *startf,
static inline void timer_stats_account_hrtimer(struct hrtimer *timer)
{
+ if (likely(!timer->start_pid))
+ return;
timer_stats_update_stats(timer, timer->start_pid, timer->start_site,
timer->function, timer->start_comm, 0);
}
@@ -456,6 +459,8 @@ extern void __timer_stats_hrtimer_set_start_info(struct hrtimer *timer,
static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer)
{
+ if (likely(!timer_stats_active))
+ return;
__timer_stats_hrtimer_set_start_info(timer, __builtin_return_address(0));
}
diff --git a/include/linux/timer.h b/include/linux/timer.h
index ccf882e..be62ec2 100644
--- a/include/linux/timer.h
+++ b/include/linux/timer.h
@@ -190,6 +190,8 @@ extern unsigned long get_next_timer_interrupt(unsigned long now);
*/
#ifdef CONFIG_TIMER_STATS
+extern int timer_stats_active;
+
#define TIMER_STATS_FLAG_DEFERRABLE 0x1
extern void init_timer_stats(void);
@@ -203,6 +205,8 @@ extern void __timer_stats_timer_set_start_info(struct timer_list *timer,
static inline void timer_stats_timer_set_start_info(struct timer_list *timer)
{
+ if (likely(!timer_stats_active))
+ return;
__timer_stats_timer_set_start_info(timer, __builtin_return_address(0));
}
diff --git a/kernel/time/timer_stats.c b/kernel/time/timer_stats.c
index c994530..4cde8b9 100644
--- a/kernel/time/timer_stats.c
+++ b/kernel/time/timer_stats.c
@@ -96,7 +96,7 @@ static DEFINE_MUTEX(show_mutex);
/*
* Collection status, active/inactive:
*/
-static int __read_mostly active;
+int __read_mostly timer_stats_active;
/*
* Beginning/end timestamps of measurement:
@@ -242,7 +242,7 @@ void timer_stats_update_stats(void *timer, pid_t pid, void *startf,
struct entry *entry, input;
unsigned long flags;
- if (likely(!active))
+ if (likely(!timer_stats_active))
return;
lock = &per_cpu(lookup_lock, raw_smp_processor_id());
@@ -254,7 +254,7 @@ void timer_stats_update_stats(void *timer, pid_t pid, void *startf,
input.timer_flag = timer_flag;
spin_lock_irqsave(lock, flags);
- if (!active)
+ if (!timer_stats_active)
goto out_unlock;
entry = tstat_lookup(&input, comm);
@@ -290,7 +290,7 @@ static int tstats_show(struct seq_file *m, void *v)
/*
* If still active then calculate up to now:
*/
- if (active)
+ if (timer_stats_active)
time_stop = ktime_get();
time = ktime_sub(time_stop, time_start);
@@ -368,18 +368,18 @@ static ssize_t tstats_write(struct file *file, const char __user *buf,
mutex_lock(&show_mutex);
switch (ctl[0]) {
case '0':
- if (active) {
- active = 0;
+ if (timer_stats_active) {
+ timer_stats_active = 0;
time_stop = ktime_get();
sync_access();
}
break;
case '1':
- if (!active) {
+ if (!timer_stats_active) {
reset_entries();
time_start = ktime_get();
smp_mb();
- active = 1;
+ timer_stats_active = 1;
}
break;
default:
diff --git a/kernel/timer.c b/kernel/timer.c
index 54d3912..0b36b9e 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -380,6 +380,8 @@ static void timer_stats_account_timer(struct timer_list *timer)
{
unsigned int flag = 0;
+ if (likely(!timer->start_site))
+ return;
if (unlikely(tbase_get_deferrable(timer->base)))
flag |= TIMER_STATS_FLAG_DEFERRABLE;
^ permalink raw reply related [flat|nested] 4+ messages in thread
end of thread, other threads:[~2009-06-24 9:48 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2009-06-23 14:12 [PATCH/Resend] timer stats: add quick check to avoid function calls Heiko Carstens
2009-06-23 15:08 ` Ingo Molnar
2009-06-23 15:38 ` Heiko Carstens
2009-06-24 9:47 ` [tip:timers/urgent] timer stats: Optimize by adding " tip-bot for Heiko Carstens
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