[PATCH v3] MIPS: Add a high resolution sched_clock() via cnt32_to_63().

[PATCH v3] MIPS: Add a high resolution sched_clock() via cnt32_to_63().

[Wu Zhangjin]

From: Wu Zhangjin <wuzhangjin@gmail.com>

(This v3 revision incorporates with the feedbacks from Ingo, Ralf and Sergei.)

This patch adds a cnt32_to_63() and MIPS c0 count based sched_clock(),
which provides high resolution. and also, one new kernel option
(HR_SCHED_CLOCK) is added to enable/disable this sched_clock().

Without it, the Ftrace for MIPS will give useless timestamp information.

Because cnt32_to_63() needs to be called at least once per half period
to work properly, Differ from the old version, this v2 revision set up a
kernel timer to ensure the requirement of some MIPSs which have short c0
count period.

Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
---
 arch/mips/Kconfig           |   18 ++++++++++++++
 arch/mips/kernel/csrc-r4k.c |   55 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 73 insertions(+), 0 deletions(-)

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index b342197..5ea55f5 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -1952,6 +1952,24 @@ config NR_CPUS
 source "kernel/time/Kconfig"
 
 #
+# High Resolution sched_clock() Configuration
+#
+
+config HR_SCHED_CLOCK
+	bool "High Resolution sched_clock()"
+	depends on CSRC_R4K
+	default n
+	help
+	  This option enables the MIPS c0 count based high resolution
+	  sched_clock().
+
+	  If you need a ns precision timestamp, you are recommended to enable
+	  this option. For example, If you are using the Ftrace subsystem to do
+	  real time tracing, this option is needed.
+
+	  If unsure, disable it.
+
+#
 # Timer Interrupt Frequency Configuration
 #
 
diff --git a/arch/mips/kernel/csrc-r4k.c b/arch/mips/kernel/csrc-r4k.c
index e95a3cd..e287f0d 100644
--- a/arch/mips/kernel/csrc-r4k.c
+++ b/arch/mips/kernel/csrc-r4k.c
@@ -10,6 +10,57 @@
 
 #include <asm/time.h>
 
+#ifdef CONFIG_HR_SCHED_CLOCK
+#include <linux/cnt32_to_63.h>
+#include <linux/timer.h>
+
+/*
+ * MIPS sched_clock implementation.
+ *
+ * because cnt32_to_63() needs to be called at least once per half period to
+ * work properly, and some of the MIPS frequency is high, perhaps a kernel
+ * timer is needed to be set up to ensure this requirement is always met.
+ * Please refer to arch/arm/plat-orion/time.c and include/linux/cnt32_to_63.h
+ */
+static unsigned long __read_mostly tclk2ns_scale;
+static unsigned long __read_mostly tclk2ns_scale_factor;
+
+unsigned long long notrace sched_clock(void)
+{
+	unsigned long long v = cnt32_to_63(read_c0_count());
+	return (v * tclk2ns_scale) >> tclk2ns_scale_factor;
+}
+
+static struct timer_list cnt32_to_63_keepwarm_timer;
+
+static void cnt32_to_63_keepwarm(unsigned long data)
+{
+	mod_timer(&cnt32_to_63_keepwarm_timer, round_jiffies(jiffies + data));
+	(void) sched_clock();
+}
+
+static void __init setup_sched_clock(struct clocksource *cs, unsigned long tclk)
+{
+	unsigned long long v;
+	unsigned long data;
+
+	v = cs->mult;
+	/*
+	 * We want an even value to automatically clear the top bit
+	 * returned by cnt32_to_63() without an additional run time
+	 * instruction. So if the LSB is 1 then round it up.
+	 */
+	if (v & 1)
+		v++;
+	tclk2ns_scale = v;
+	tclk2ns_scale_factor = cs->shift;
+
+	data = 0x80000000 / tclk * HZ;
+	setup_timer(&cnt32_to_63_keepwarm_timer, cnt32_to_63_keepwarm, data);
+	mod_timer(&cnt32_to_63_keepwarm_timer, round_jiffies(jiffies + data));
+}
+#endif	/* !CONFIG_HR_SCHED_CLOCK */
+
 static cycle_t c0_hpt_read(struct clocksource *cs)
 {
 	return read_c0_count();
@@ -32,6 +83,10 @@ int __init init_r4k_clocksource(void)
 
 	clocksource_set_clock(&clocksource_mips, mips_hpt_frequency);
 
+#ifdef CONFIG_HR_SCHED_CLOCK
+	setup_sched_clock(&clocksource_mips, mips_hpt_frequency);
+#endif
+
 	clocksource_register(&clocksource_mips);
 
 	return 0;
-- 
1.6.2.1

Re: [PATCH v3] MIPS: Add a high resolution sched_clock() via cnt32_to_63().

[Sergei Shtylyov]

Hello.

Wu Zhangjin wrote:

> From: Wu Zhangjin <wuzhangjin@gmail.com>
>
> (This v3 revision incorporates with the feedbacks from Ingo, Ralf and Sergei.)
>
> This patch adds a cnt32_to_63() and MIPS c0 count based sched_clock(),
> which provides high resolution. and also, one new kernel option
> (HR_SCHED_CLOCK) is added to enable/disable this sched_clock().
>
> Without it, the Ftrace for MIPS will give useless timestamp information.
>
> Because cnt32_to_63() needs to be called at least once per half period
> to work properly, Differ from the old version, this v2 revision set up a
> kernel timer to ensure the requirement of some MIPSs which have short c0
> count period.
>
> Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
> ---
>  arch/mips/Kconfig           |   18 ++++++++++++++
>  arch/mips/kernel/csrc-r4k.c |   55 +++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 73 insertions(+), 0 deletions(-)
>
> diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> index b342197..5ea55f5 100644
> --- a/arch/mips/Kconfig
> +++ b/arch/mips/Kconfig
> @@ -1952,6 +1952,24 @@ config NR_CPUS
>  source "kernel/time/Kconfig"
>  
>  #
> +# High Resolution sched_clock() Configuration
> +#
> +
> +config HR_SCHED_CLOCK
> +	bool "High Resolution sched_clock()"
> +	depends on CSRC_R4K
> +	default n
> +	help
> +	  This option enables the MIPS c0 count based high resolution
> +	  sched_clock().
> +
> +	  If you need a ns precision timestamp, you are recommended to enable
> +	  this option. For example, If you are using the Ftrace subsystem to do
> +	  real time tracing, this option is needed.
> +
> +	  If unsure, disable it.
> +
> +#
>  # Timer Interrupt Frequency Configuration
>  #
>  
> diff --git a/arch/mips/kernel/csrc-r4k.c b/arch/mips/kernel/csrc-r4k.c
> index e95a3cd..e287f0d 100644
> --- a/arch/mips/kernel/csrc-r4k.c
> +++ b/arch/mips/kernel/csrc-r4k.c
> @@ -10,6 +10,57 @@
>  
>  #include <asm/time.h>
>  
> +#ifdef CONFIG_HR_SCHED_CLOCK
> +#include <linux/cnt32_to_63.h>
> +#include <linux/timer.h>
> +
> +/*
> + * MIPS sched_clock implementation.
> + *
> + * because cnt32_to_63() needs to be called at least once per half period to
> + * work properly, and some of the MIPS frequency is high, perhaps a kernel
> + * timer is needed to be set up to ensure this requirement is always met.
> + * Please refer to arch/arm/plat-orion/time.c and include/linux/cnt32_to_63.h
> + */
> +static unsigned long __read_mostly tclk2ns_scale;
> +static unsigned long __read_mostly tclk2ns_scale_factor;
> +
> +unsigned long long notrace sched_clock(void)
> +{
> +	unsigned long long v = cnt32_to_63(read_c0_count());
> +	return (v * tclk2ns_scale) >> tclk2ns_scale_factor;
> +}
> +
> +static struct timer_list cnt32_to_63_keepwarm_timer;
> +
> +static void cnt32_to_63_keepwarm(unsigned long data)
> +{
> +	mod_timer(&cnt32_to_63_keepwarm_timer, round_jiffies(jiffies + data));
> +	(void) sched_clock();
> +}
> +
> +static void __init setup_sched_clock(struct clocksource *cs, unsigned long tclk)
> +{
> +	unsigned long long v;
> +	unsigned long data;
> +
> +	v = cs->mult;
> +	/*
> +	 * We want an even value to automatically clear the top bit
> +	 * returned by cnt32_to_63() without an additional run time
> +	 * instruction. So if the LSB is 1 then round it up.
> +	 */
> +	if (v & 1)
> +		v++;
> +	tclk2ns_scale = v;
> +	tclk2ns_scale_factor = cs->shift;
> +
> +	data = 0x80000000 / tclk * HZ;
> +	setup_timer(&cnt32_to_63_keepwarm_timer, cnt32_to_63_keepwarm, data);
> +	mod_timer(&cnt32_to_63_keepwarm_timer, round_jiffies(jiffies + data));
> +}
> +#endif	/* !CONFIG_HR_SCHED_CLOCK */
> +
>  static cycle_t c0_hpt_read(struct clocksource *cs)
>  {
>  	return read_c0_count();
> @@ -32,6 +83,10 @@ int __init init_r4k_clocksource(void)
>  
>  	clocksource_set_clock(&clocksource_mips, mips_hpt_frequency);
>  
> +#ifdef CONFIG_HR_SCHED_CLOCK
> +	setup_sched_clock(&clocksource_mips, mips_hpt_frequency);
> +#endif
> +
>   

   According to CodingStyle #ifdef's in the code are frowned upon. I 
suggest that you add an empty setup_sched_clock() definition under #else 
above and have the call here without #ifdef. That's the preferred way of 
doing such things...

WBR, Sergei

Re: [PATCH v3] MIPS: Add a high resolution sched_clock() via cnt32_to_63().

[Wu Zhangjin]

On Sun, 2009-11-22 at 22:03 +0300, Sergei Shtylyov wrote:
> Hello.
> 
> Wu Zhangjin wrote:
> 
> > From: Wu Zhangjin <wuzhangjin@gmail.com>
> >
> > (This v3 revision incorporates with the feedbacks from Ingo, Ralf and Sergei.)
> >
> > This patch adds a cnt32_to_63() and MIPS c0 count based sched_clock(),
> > which provides high resolution. and also, one new kernel option
> > (HR_SCHED_CLOCK) is added to enable/disable this sched_clock().
> >
> > Without it, the Ftrace for MIPS will give useless timestamp information.
> >
> > Because cnt32_to_63() needs to be called at least once per half period
> > to work properly, Differ from the old version, this v2 revision set up a
> > kernel timer to ensure the requirement of some MIPSs which have short c0
> > count period.
> >
> > Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
> > ---
> >  arch/mips/Kconfig           |   18 ++++++++++++++
> >  arch/mips/kernel/csrc-r4k.c |   55 +++++++++++++++++++++++++++++++++++++++++++
> >  2 files changed, 73 insertions(+), 0 deletions(-)
> >
> > diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> > index b342197..5ea55f5 100644
> > --- a/arch/mips/Kconfig
> > +++ b/arch/mips/Kconfig
> > @@ -1952,6 +1952,24 @@ config NR_CPUS
> >  source "kernel/time/Kconfig"
> >  
> >  #
> > +# High Resolution sched_clock() Configuration
> > +#
> > +
> > +config HR_SCHED_CLOCK
> > +	bool "High Resolution sched_clock()"
> > +	depends on CSRC_R4K
> > +	default n
> > +	help
> > +	  This option enables the MIPS c0 count based high resolution
> > +	  sched_clock().
> > +
> > +	  If you need a ns precision timestamp, you are recommended to enable
> > +	  this option. For example, If you are using the Ftrace subsystem to do
> > +	  real time tracing, this option is needed.
> > +
> > +	  If unsure, disable it.
> > +
> > +#
> >  # Timer Interrupt Frequency Configuration
> >  #
> >  
> > diff --git a/arch/mips/kernel/csrc-r4k.c b/arch/mips/kernel/csrc-r4k.c
> > index e95a3cd..e287f0d 100644
> > --- a/arch/mips/kernel/csrc-r4k.c
> > +++ b/arch/mips/kernel/csrc-r4k.c
> > @@ -10,6 +10,57 @@
> >  
> >  #include <asm/time.h>
> >  
> > +#ifdef CONFIG_HR_SCHED_CLOCK
> > +#include <linux/cnt32_to_63.h>
> > +#include <linux/timer.h>
> > +
> > +/*
> > + * MIPS sched_clock implementation.
> > + *
> > + * because cnt32_to_63() needs to be called at least once per half period to
> > + * work properly, and some of the MIPS frequency is high, perhaps a kernel
> > + * timer is needed to be set up to ensure this requirement is always met.
> > + * Please refer to arch/arm/plat-orion/time.c and include/linux/cnt32_to_63.h
> > + */
> > +static unsigned long __read_mostly tclk2ns_scale;
> > +static unsigned long __read_mostly tclk2ns_scale_factor;
> > +
> > +unsigned long long notrace sched_clock(void)
> > +{
> > +	unsigned long long v = cnt32_to_63(read_c0_count());
> > +	return (v * tclk2ns_scale) >> tclk2ns_scale_factor;
> > +}
> > +
> > +static struct timer_list cnt32_to_63_keepwarm_timer;
> > +
> > +static void cnt32_to_63_keepwarm(unsigned long data)
> > +{
> > +	mod_timer(&cnt32_to_63_keepwarm_timer, round_jiffies(jiffies + data));
> > +	(void) sched_clock();
> > +}
> > +
> > +static void __init setup_sched_clock(struct clocksource *cs, unsigned long tclk)
> > +{
> > +	unsigned long long v;
> > +	unsigned long data;
> > +
> > +	v = cs->mult;
> > +	/*
> > +	 * We want an even value to automatically clear the top bit
> > +	 * returned by cnt32_to_63() without an additional run time
> > +	 * instruction. So if the LSB is 1 then round it up.
> > +	 */
> > +	if (v & 1)
> > +		v++;
> > +	tclk2ns_scale = v;
> > +	tclk2ns_scale_factor = cs->shift;
> > +
> > +	data = 0x80000000 / tclk * HZ;
> > +	setup_timer(&cnt32_to_63_keepwarm_timer, cnt32_to_63_keepwarm, data);
> > +	mod_timer(&cnt32_to_63_keepwarm_timer, round_jiffies(jiffies + data));
> > +}
> > +#endif	/* !CONFIG_HR_SCHED_CLOCK */
> > +
> >  static cycle_t c0_hpt_read(struct clocksource *cs)
> >  {
> >  	return read_c0_count();
> > @@ -32,6 +83,10 @@ int __init init_r4k_clocksource(void)
> >  
> >  	clocksource_set_clock(&clocksource_mips, mips_hpt_frequency);
> >  
> > +#ifdef CONFIG_HR_SCHED_CLOCK
> > +	setup_sched_clock(&clocksource_mips, mips_hpt_frequency);
> > +#endif
> > +
> >   
> 
>    According to CodingStyle #ifdef's in the code are frowned upon. I 
> suggest that you add an empty setup_sched_clock() definition under #else 
> above and have the call here without #ifdef. That's the preferred way of 
> doing such things...
> 

Done, thanks!

Wil resend it later.

Re: [PATCH v3] MIPS: Add a high resolution sched_clock() via cnt32_to_63().

[Ingo Molnar]

* Wu Zhangjin <wuzhangjin@gmail.com> wrote:

> On Sun, 2009-11-22 at 22:03 +0300, Sergei Shtylyov wrote:
> > Hello.
> > 
> > Wu Zhangjin wrote:
> > 
> > > From: Wu Zhangjin <wuzhangjin@gmail.com>
> > >
> > > (This v3 revision incorporates with the feedbacks from Ingo, Ralf and Sergei.)
> > >
> > > This patch adds a cnt32_to_63() and MIPS c0 count based sched_clock(),
> > > which provides high resolution. and also, one new kernel option
> > > (HR_SCHED_CLOCK) is added to enable/disable this sched_clock().
> > >
> > > Without it, the Ftrace for MIPS will give useless timestamp information.
> > >
> > > Because cnt32_to_63() needs to be called at least once per half period
> > > to work properly, Differ from the old version, this v2 revision set up a
> > > kernel timer to ensure the requirement of some MIPSs which have short c0
> > > count period.
> > >
> > > Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
> > > ---
> > >  arch/mips/Kconfig           |   18 ++++++++++++++
> > >  arch/mips/kernel/csrc-r4k.c |   55 +++++++++++++++++++++++++++++++++++++++++++
> > >  2 files changed, 73 insertions(+), 0 deletions(-)
> > >
> > > diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> > > index b342197..5ea55f5 100644
> > > --- a/arch/mips/Kconfig
> > > +++ b/arch/mips/Kconfig
> > > @@ -1952,6 +1952,24 @@ config NR_CPUS
> > >  source "kernel/time/Kconfig"
> > >  
> > >  #
> > > +# High Resolution sched_clock() Configuration
> > > +#
> > > +
> > > +config HR_SCHED_CLOCK
> > > +	bool "High Resolution sched_clock()"
> > > +	depends on CSRC_R4K
> > > +	default n
> > > +	help
> > > +	  This option enables the MIPS c0 count based high resolution
> > > +	  sched_clock().
> > > +
> > > +	  If you need a ns precision timestamp, you are recommended to enable
> > > +	  this option. For example, If you are using the Ftrace subsystem to do
> > > +	  real time tracing, this option is needed.
> > > +
> > > +	  If unsure, disable it.
> > > +
> > > +#
> > >  # Timer Interrupt Frequency Configuration
> > >  #
> > >  
> > > diff --git a/arch/mips/kernel/csrc-r4k.c b/arch/mips/kernel/csrc-r4k.c
> > > index e95a3cd..e287f0d 100644
> > > --- a/arch/mips/kernel/csrc-r4k.c
> > > +++ b/arch/mips/kernel/csrc-r4k.c
> > > @@ -10,6 +10,57 @@
> > >  
> > >  #include <asm/time.h>
> > >  
> > > +#ifdef CONFIG_HR_SCHED_CLOCK
> > > +#include <linux/cnt32_to_63.h>
> > > +#include <linux/timer.h>
> > > +
> > > +/*
> > > + * MIPS sched_clock implementation.
> > > + *
> > > + * because cnt32_to_63() needs to be called at least once per half period to
> > > + * work properly, and some of the MIPS frequency is high, perhaps a kernel
> > > + * timer is needed to be set up to ensure this requirement is always met.
> > > + * Please refer to arch/arm/plat-orion/time.c and include/linux/cnt32_to_63.h
> > > + */
> > > +static unsigned long __read_mostly tclk2ns_scale;
> > > +static unsigned long __read_mostly tclk2ns_scale_factor;
> > > +
> > > +unsigned long long notrace sched_clock(void)
> > > +{
> > > +	unsigned long long v = cnt32_to_63(read_c0_count());
> > > +	return (v * tclk2ns_scale) >> tclk2ns_scale_factor;
> > > +}
> > > +
> > > +static struct timer_list cnt32_to_63_keepwarm_timer;
> > > +
> > > +static void cnt32_to_63_keepwarm(unsigned long data)
> > > +{
> > > +	mod_timer(&cnt32_to_63_keepwarm_timer, round_jiffies(jiffies + data));
> > > +	(void) sched_clock();
> > > +}
> > > +
> > > +static void __init setup_sched_clock(struct clocksource *cs, unsigned long tclk)
> > > +{
> > > +	unsigned long long v;
> > > +	unsigned long data;
> > > +
> > > +	v = cs->mult;
> > > +	/*
> > > +	 * We want an even value to automatically clear the top bit
> > > +	 * returned by cnt32_to_63() without an additional run time
> > > +	 * instruction. So if the LSB is 1 then round it up.
> > > +	 */
> > > +	if (v & 1)
> > > +		v++;
> > > +	tclk2ns_scale = v;
> > > +	tclk2ns_scale_factor = cs->shift;
> > > +
> > > +	data = 0x80000000 / tclk * HZ;
> > > +	setup_timer(&cnt32_to_63_keepwarm_timer, cnt32_to_63_keepwarm, data);
> > > +	mod_timer(&cnt32_to_63_keepwarm_timer, round_jiffies(jiffies + data));
> > > +}
> > > +#endif	/* !CONFIG_HR_SCHED_CLOCK */
> > > +
> > >  static cycle_t c0_hpt_read(struct clocksource *cs)
> > >  {
> > >  	return read_c0_count();
> > > @@ -32,6 +83,10 @@ int __init init_r4k_clocksource(void)
> > >  
> > >  	clocksource_set_clock(&clocksource_mips, mips_hpt_frequency);
> > >  
> > > +#ifdef CONFIG_HR_SCHED_CLOCK
> > > +	setup_sched_clock(&clocksource_mips, mips_hpt_frequency);
> > > +#endif
> > > +
> > >   
> > 
> >    According to CodingStyle #ifdef's in the code are frowned upon. I 
> > suggest that you add an empty setup_sched_clock() definition under #else 
> > above and have the call here without #ifdef. That's the preferred way of 
> > doing such things...
> > 
> 
> Done, thanks!
> 
> Wil resend it later.

The proper solution would be what i suggested in my previous mail: to 
put it into a separate .c file. It's easy as the code has its own 
Kconfig value already. The only #ifdef is out of sight in a .h file.

	Ingo

Re: [PATCH v3] MIPS: Add a high resolution sched_clock() via cnt32_to_63().

[Wu Zhangjin]

On Mon, 2009-11-23 at 09:44 +0100, Ingo Molnar wrote:
> * Wu Zhangjin <wuzhangjin@gmail.com> wrote:
> 
> > On Sun, 2009-11-22 at 22:03 +0300, Sergei Shtylyov wrote:
> > > Hello.
> > > 
> > > Wu Zhangjin wrote:
> > > 
> > > > From: Wu Zhangjin <wuzhangjin@gmail.com>
> > > >
> > > > (This v3 revision incorporates with the feedbacks from Ingo, Ralf and Sergei.)
> > > >
> > > > This patch adds a cnt32_to_63() and MIPS c0 count based sched_clock(),
> > > > which provides high resolution. and also, one new kernel option
> > > > (HR_SCHED_CLOCK) is added to enable/disable this sched_clock().
> > > >
> > > > Without it, the Ftrace for MIPS will give useless timestamp information.
> > > >
> > > > Because cnt32_to_63() needs to be called at least once per half period
> > > > to work properly, Differ from the old version, this v2 revision set up a
> > > > kernel timer to ensure the requirement of some MIPSs which have short c0
> > > > count period.
> > > >
> > > > Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
> > > > ---
> > > >  arch/mips/Kconfig           |   18 ++++++++++++++
> > > >  arch/mips/kernel/csrc-r4k.c |   55 +++++++++++++++++++++++++++++++++++++++++++
> > > >  2 files changed, 73 insertions(+), 0 deletions(-)
> > > >
> > > > diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> > > > index b342197..5ea55f5 100644
> > > > --- a/arch/mips/Kconfig
> > > > +++ b/arch/mips/Kconfig
> > > > @@ -1952,6 +1952,24 @@ config NR_CPUS
> > > >  source "kernel/time/Kconfig"
> > > >  
> > > >  #
> > > > +# High Resolution sched_clock() Configuration
> > > > +#
> > > > +
> > > > +config HR_SCHED_CLOCK
> > > > +	bool "High Resolution sched_clock()"
> > > > +	depends on CSRC_R4K
> > > > +	default n
> > > > +	help
> > > > +	  This option enables the MIPS c0 count based high resolution
> > > > +	  sched_clock().
> > > > +
> > > > +	  If you need a ns precision timestamp, you are recommended to enable
> > > > +	  this option. For example, If you are using the Ftrace subsystem to do
> > > > +	  real time tracing, this option is needed.
> > > > +
> > > > +	  If unsure, disable it.
> > > > +
> > > > +#
> > > >  # Timer Interrupt Frequency Configuration
> > > >  #
> > > >  
> > > > diff --git a/arch/mips/kernel/csrc-r4k.c b/arch/mips/kernel/csrc-r4k.c
> > > > index e95a3cd..e287f0d 100644
> > > > --- a/arch/mips/kernel/csrc-r4k.c
> > > > +++ b/arch/mips/kernel/csrc-r4k.c
> > > > @@ -10,6 +10,57 @@
> > > >  
> > > >  #include <asm/time.h>
> > > >  
> > > > +#ifdef CONFIG_HR_SCHED_CLOCK
> > > > +#include <linux/cnt32_to_63.h>
> > > > +#include <linux/timer.h>
> > > > +
> > > > +/*
> > > > + * MIPS sched_clock implementation.
> > > > + *
> > > > + * because cnt32_to_63() needs to be called at least once per half period to
> > > > + * work properly, and some of the MIPS frequency is high, perhaps a kernel
> > > > + * timer is needed to be set up to ensure this requirement is always met.
> > > > + * Please refer to arch/arm/plat-orion/time.c and include/linux/cnt32_to_63.h
> > > > + */
> > > > +static unsigned long __read_mostly tclk2ns_scale;
> > > > +static unsigned long __read_mostly tclk2ns_scale_factor;
> > > > +
> > > > +unsigned long long notrace sched_clock(void)
> > > > +{
> > > > +	unsigned long long v = cnt32_to_63(read_c0_count());
> > > > +	return (v * tclk2ns_scale) >> tclk2ns_scale_factor;
> > > > +}
> > > > +
> > > > +static struct timer_list cnt32_to_63_keepwarm_timer;
> > > > +
> > > > +static void cnt32_to_63_keepwarm(unsigned long data)
> > > > +{
> > > > +	mod_timer(&cnt32_to_63_keepwarm_timer, round_jiffies(jiffies + data));
> > > > +	(void) sched_clock();
> > > > +}
> > > > +
> > > > +static void __init setup_sched_clock(struct clocksource *cs, unsigned long tclk)
> > > > +{
> > > > +	unsigned long long v;
> > > > +	unsigned long data;
> > > > +
> > > > +	v = cs->mult;
> > > > +	/*
> > > > +	 * We want an even value to automatically clear the top bit
> > > > +	 * returned by cnt32_to_63() without an additional run time
> > > > +	 * instruction. So if the LSB is 1 then round it up.
> > > > +	 */
> > > > +	if (v & 1)
> > > > +		v++;
> > > > +	tclk2ns_scale = v;
> > > > +	tclk2ns_scale_factor = cs->shift;
> > > > +
> > > > +	data = 0x80000000 / tclk * HZ;
> > > > +	setup_timer(&cnt32_to_63_keepwarm_timer, cnt32_to_63_keepwarm, data);
> > > > +	mod_timer(&cnt32_to_63_keepwarm_timer, round_jiffies(jiffies + data));
> > > > +}
> > > > +#endif	/* !CONFIG_HR_SCHED_CLOCK */
> > > > +
> > > >  static cycle_t c0_hpt_read(struct clocksource *cs)
> > > >  {
> > > >  	return read_c0_count();
> > > > @@ -32,6 +83,10 @@ int __init init_r4k_clocksource(void)
> > > >  
> > > >  	clocksource_set_clock(&clocksource_mips, mips_hpt_frequency);
> > > >  
> > > > +#ifdef CONFIG_HR_SCHED_CLOCK
> > > > +	setup_sched_clock(&clocksource_mips, mips_hpt_frequency);
> > > > +#endif
> > > > +
> > > >   
> > > 
> > >    According to CodingStyle #ifdef's in the code are frowned upon. I 
> > > suggest that you add an empty setup_sched_clock() definition under #else 
> > > above and have the call here without #ifdef. That's the preferred way of 
> > > doing such things...
> > > 
> > 
> > Done, thanks!
> > 
> > Wil resend it later.
> 
> The proper solution would be what i suggested in my previous mail: to 
> put it into a separate .c file. It's easy as the code has its own 
> Kconfig value already. The only #ifdef is out of sight in a .h file.
> 

Done, thanks!

Regards,
	Wu Zhangjin