RE: [PATCH] cpufreq: Align all CPUs to the same frequency if using shared clock
> -Original Message- > From: Viresh Kumar [mailto:viresh.ku...@linaro.org] > Sent: Wednesday, January 22, 2014 2:43 PM > To: Li, Zhuangzhi > Cc: Rafael J. Wysocki; cpuf...@vger.kernel.org; linux...@vger.kernel.org; > Linux Kernel Mailing List; Liu, Chuansheng > Subject: Re: [PATCH] cpufreq: Align all CPUs to the same frequency if using > shared clock > > On 22 January 2014 11:56, Li, Zhuangzhi wrote: > > I don't think it's a real bug in bootloader, the bootloader can set > > CPUs to different frequencies according to actually requirements(Power > > saving first or Performance first), the CPUs freq policy are initialized in > > kernel, > if the kernel want to share one CPU policy(using CPUFREQ_SHARED_TYPE_ALL > type), it should ensure all CPUs frequencies aligned first, don't depend on > the > bootloader CPUs Pre-states, then the kernel can have better compatibility. > > > > If the kernel uses CPUFREQ_SHARED_TYPE_ALL policy, the patch can ensure > these: > > 1. If all CPUs are in the same P-state, it does nothing when cpufreq > > registering 2. If the CPUs are in different P-states, all the other CPUs are > aligned once to current frequency of CPU0 according to the present policy. > > I thought, as you are asking kernel to keep same freq on all of them, then > same > should be true for bootloaders. > > Otherwise it was okay. Yes, but most of the platforms(ARM) only enable one CPU Core in bootloader or Bios because of multiple threads(SMP) are not supported, and the other Cores stay in default configuration for saving power in bootloader, kernel is responsible for booting up the other Cores from default frequencies for SMP. Cpufreq driver need to init them to required P-state before governor active when using CPUFREQ_SHARED_TYPE_ALL policy. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
RE: [PATCH] cpufreq: Align all CPUs to the same frequency if using shared clock
-Original Message- From: Viresh Kumar [mailto:viresh.ku...@linaro.org] Sent: Wednesday, January 22, 2014 2:43 PM To: Li, Zhuangzhi Cc: Rafael J. Wysocki; cpuf...@vger.kernel.org; linux...@vger.kernel.org; Linux Kernel Mailing List; Liu, Chuansheng Subject: Re: [PATCH] cpufreq: Align all CPUs to the same frequency if using shared clock On 22 January 2014 11:56, Li, Zhuangzhi zhuangzhi...@intel.com wrote: I don't think it's a real bug in bootloader, the bootloader can set CPUs to different frequencies according to actually requirements(Power saving first or Performance first), the CPUs freq policy are initialized in kernel, if the kernel want to share one CPU policy(using CPUFREQ_SHARED_TYPE_ALL type), it should ensure all CPUs frequencies aligned first, don't depend on the bootloader CPUs Pre-states, then the kernel can have better compatibility. If the kernel uses CPUFREQ_SHARED_TYPE_ALL policy, the patch can ensure these: 1. If all CPUs are in the same P-state, it does nothing when cpufreq registering 2. If the CPUs are in different P-states, all the other CPUs are aligned once to current frequency of CPU0 according to the present policy. I thought, as you are asking kernel to keep same freq on all of them, then same should be true for bootloaders. Otherwise it was okay. Yes, but most of the platforms(ARMx86) only enable one CPU Core in bootloader or Bios because of multiple threads(SMP) are not supported, and the other Cores stay in default configuration for saving power in bootloader, kernel is responsible for booting up the other Cores from default frequencies for SMP. Cpufreq driver need to init them to required P-state before governor active when using CPUFREQ_SHARED_TYPE_ALL policy. -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] cpufreq: Align all CPUs to the same frequency if using shared clock
On 22 January 2014 11:56, Li, Zhuangzhi wrote: > I don't think it's a real bug in bootloader, the bootloader can set CPUs to > different frequencies according to actually requirements(Power saving first > or Performance first), > the CPUs freq policy are initialized in kernel, if the kernel want to share > one CPU policy(using CPUFREQ_SHARED_TYPE_ALL type), it should ensure all CPUs > frequencies aligned first, > don't depend on the bootloader CPUs Pre-states, then the kernel can have > better compatibility. > > If the kernel uses CPUFREQ_SHARED_TYPE_ALL policy, the patch can ensure these: > 1. If all CPUs are in the same P-state, it does nothing when cpufreq > registering > 2. If the CPUs are in different P-states, all the other CPUs are aligned once > to current frequency of CPU0 according to the present policy. I thought, as you are asking kernel to keep same freq on all of them, then same should be true for bootloaders. Otherwise it was okay. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
RE: [PATCH] cpufreq: Align all CPUs to the same frequency if using shared clock
> -Original Message- > From: Viresh Kumar [mailto:viresh.ku...@linaro.org] > Sent: Wednesday, January 22, 2014 1:18 PM > To: Li, Zhuangzhi > Cc: Rafael J. Wysocki; cpuf...@vger.kernel.org; linux...@vger.kernel.org; > Linux Kernel Mailing List; Liu, Chuansheng > Subject: Re: [PATCH] cpufreq: Align all CPUs to the same frequency if using > shared clock > > On 21 January 2014 13:42, Viresh Kumar wrote: > > On 21 January 2014 12:56, Li, Zhuangzhi wrote: > >> Thanks for reviewing. > > > > Its my job :) > > > >> Sorry for make you misunderstanding, on our x86 platform, we want all the > CPUs share one policy by setting CPUFREQ_SHARED_TYPE_ALL, not share one > HW clock line. > > > > I see.. Then probably your patch makes sense. But it is obviously not > > required for every platform that exists today. > > > > Please update it to do it only for drivers that have set > > CPUFREQ_SHARED_TYPE_ALL.. > > One more thing, who has set different frequencies to these cores? > I hope kernel hasn't ? > > In that case, probably you are fixing a bootloader bug in kernel? > What about doing this in bootloader then? I don't think it's a real bug in bootloader, the bootloader can set CPUs to different frequencies according to actually requirements(Power saving first or Performance first), the CPUs freq policy are initialized in kernel, if the kernel want to share one CPU policy(using CPUFREQ_SHARED_TYPE_ALL type), it should ensure all CPUs frequencies aligned first, don't depend on the bootloader CPUs Pre-states, then the kernel can have better compatibility. If the kernel uses CPUFREQ_SHARED_TYPE_ALL policy, the patch can ensure these: 1. If all CPUs are in the same P-state, it does nothing when cpufreq registering 2. If the CPUs are in different P-states, all the other CPUs are aligned once to current frequency of CPU0 according to the present policy. > > -- > virehs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] cpufreq: Align all CPUs to the same frequency if using shared clock
On 21 January 2014 13:42, Viresh Kumar wrote: > On 21 January 2014 12:56, Li, Zhuangzhi wrote: >> Thanks for reviewing. > > Its my job :) > >> Sorry for make you misunderstanding, on our x86 platform, we want all the >> CPUs share one policy by setting CPUFREQ_SHARED_TYPE_ALL, not share one HW >> clock line. > > I see.. Then probably your patch makes sense. But it is > obviously not required for every platform that exists today. > > Please update it to do it only for drivers that have set > CPUFREQ_SHARED_TYPE_ALL.. One more thing, who has set different frequencies to these cores? I hope kernel hasn't ? In that case, probably you are fixing a bootloader bug in kernel? What about doing this in bootloader then? -- virehs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] cpufreq: Align all CPUs to the same frequency if using shared clock
On 21 January 2014 12:56, Li, Zhuangzhi wrote: > Thanks for reviewing. Its my job :) > Sorry for make you misunderstanding, on our x86 platform, we want all the > CPUs share one policy by setting CPUFREQ_SHARED_TYPE_ALL, not share one HW > clock line. I see.. Then probably your patch makes sense. But it is obviously not required for every platform that exists today. Please update it to do it only for drivers that have set CPUFREQ_SHARED_TYPE_ALL.. @Rafael: I hope you agree? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] cpufreq: Align all CPUs to the same frequency if using shared clock
On 21 January 2014 12:56, Li, Zhuangzhi zhuangzhi...@intel.com wrote: Thanks for reviewing. Its my job :) Sorry for make you misunderstanding, on our x86 platform, we want all the CPUs share one policy by setting CPUFREQ_SHARED_TYPE_ALL, not share one HW clock line. I see.. Then probably your patch makes sense. But it is obviously not required for every platform that exists today. Please update it to do it only for drivers that have set CPUFREQ_SHARED_TYPE_ALL.. @Rafael: I hope you agree? -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] cpufreq: Align all CPUs to the same frequency if using shared clock
On 21 January 2014 13:42, Viresh Kumar viresh.ku...@linaro.org wrote: On 21 January 2014 12:56, Li, Zhuangzhi zhuangzhi...@intel.com wrote: Thanks for reviewing. Its my job :) Sorry for make you misunderstanding, on our x86 platform, we want all the CPUs share one policy by setting CPUFREQ_SHARED_TYPE_ALL, not share one HW clock line. I see.. Then probably your patch makes sense. But it is obviously not required for every platform that exists today. Please update it to do it only for drivers that have set CPUFREQ_SHARED_TYPE_ALL.. One more thing, who has set different frequencies to these cores? I hope kernel hasn't ? In that case, probably you are fixing a bootloader bug in kernel? What about doing this in bootloader then? -- virehs -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
RE: [PATCH] cpufreq: Align all CPUs to the same frequency if using shared clock
-Original Message- From: Viresh Kumar [mailto:viresh.ku...@linaro.org] Sent: Wednesday, January 22, 2014 1:18 PM To: Li, Zhuangzhi Cc: Rafael J. Wysocki; cpuf...@vger.kernel.org; linux...@vger.kernel.org; Linux Kernel Mailing List; Liu, Chuansheng Subject: Re: [PATCH] cpufreq: Align all CPUs to the same frequency if using shared clock On 21 January 2014 13:42, Viresh Kumar viresh.ku...@linaro.org wrote: On 21 January 2014 12:56, Li, Zhuangzhi zhuangzhi...@intel.com wrote: Thanks for reviewing. Its my job :) Sorry for make you misunderstanding, on our x86 platform, we want all the CPUs share one policy by setting CPUFREQ_SHARED_TYPE_ALL, not share one HW clock line. I see.. Then probably your patch makes sense. But it is obviously not required for every platform that exists today. Please update it to do it only for drivers that have set CPUFREQ_SHARED_TYPE_ALL.. One more thing, who has set different frequencies to these cores? I hope kernel hasn't ? In that case, probably you are fixing a bootloader bug in kernel? What about doing this in bootloader then? I don't think it's a real bug in bootloader, the bootloader can set CPUs to different frequencies according to actually requirements(Power saving first or Performance first), the CPUs freq policy are initialized in kernel, if the kernel want to share one CPU policy(using CPUFREQ_SHARED_TYPE_ALL type), it should ensure all CPUs frequencies aligned first, don't depend on the bootloader CPUs Pre-states, then the kernel can have better compatibility. If the kernel uses CPUFREQ_SHARED_TYPE_ALL policy, the patch can ensure these: 1. If all CPUs are in the same P-state, it does nothing when cpufreq registering 2. If the CPUs are in different P-states, all the other CPUs are aligned once to current frequency of CPU0 according to the present policy. -- virehs -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] cpufreq: Align all CPUs to the same frequency if using shared clock
On 22 January 2014 11:56, Li, Zhuangzhi zhuangzhi...@intel.com wrote: I don't think it's a real bug in bootloader, the bootloader can set CPUs to different frequencies according to actually requirements(Power saving first or Performance first), the CPUs freq policy are initialized in kernel, if the kernel want to share one CPU policy(using CPUFREQ_SHARED_TYPE_ALL type), it should ensure all CPUs frequencies aligned first, don't depend on the bootloader CPUs Pre-states, then the kernel can have better compatibility. If the kernel uses CPUFREQ_SHARED_TYPE_ALL policy, the patch can ensure these: 1. If all CPUs are in the same P-state, it does nothing when cpufreq registering 2. If the CPUs are in different P-states, all the other CPUs are aligned once to current frequency of CPU0 according to the present policy. I thought, as you are asking kernel to keep same freq on all of them, then same should be true for bootloaders. Otherwise it was okay. -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
RE: [PATCH] cpufreq: Align all CPUs to the same frequency if using shared clock
Thanks for reviewing.
Sorry for make you misunderstanding, on our x86 platform, we want all the CPUs
share one policy by setting CPUFREQ_SHARED_TYPE_ALL, not share one HW clock
line.
If the CPUs work at different frequency at init stage, then while the CPUs
registering, no policy to align all the CPUs to the same frequency, this caused
some conflicts with current CPUs P-state.
For example:
CPU0: P0
CPU1: P14
CPU2: P14
CPU3: P14
During all the CPUs registering, kernel considers all the CPUs work at P0 state
because of sharing CPU0 policy, but the other three CPUs really work at P14
state,
all CPUs frequency only wait to be aligned until CPU0 state changed by governor
based on shared policy.
Best Regards
Li zhuangzhi
Android System Integration Shanghai
Tel: +86 (0)21 6116 4323
-Original Message-
From: Viresh Kumar [mailto:viresh.ku...@linaro.org]
Sent: Tuesday, January 21, 2014 2:35 PM
To: Li, Zhuangzhi
Cc: Rafael J. Wysocki; cpuf...@vger.kernel.org; linux...@vger.kernel.org; Linux
Kernel Mailing List; Liu, Chuansheng
Subject: Re: [PATCH] cpufreq: Align all CPUs to the same frequency if using
shared clock
On 21 January 2014 08:35, lizhuangzhi wrote:
> Some SMP systems want to make all the possible CPUs share the clock,
> if the CPUs init frequencies aren't the same, we need to align all the
> CPUs to the same frequency while CPUs registing to avoid mismatched
> CPU's P-states.
>
> Signed-off-by: lizhuangzhi
> ---
> drivers/cpufreq/cpufreq.c |2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 8d19f7c..d00abb5 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -991,6 +991,8 @@ static int __cpufreq_add_dev(struct device *dev, struct
> subsys_interface *sif,
> * CPU because it is in the same boat. */
> policy = cpufreq_cpu_get(cpu);
> if (unlikely(policy)) {
> + /* according present policy to align all the cpus frequencies
> */
> + cpufreq_driver->target(policy, policy->cur,
> + CPUFREQ_RELATION_H);
I don't really understand why is this required? CPUs sharing clocks means that
CPUs runs on the same clock line and so all of them must be running on same
frequency. So, why do we need to call this routine? policy->cur must be the
current freq here for CPU in question.
--
viresh
--
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More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] cpufreq: Align all CPUs to the same frequency if using shared clock
On 21 January 2014 08:35, lizhuangzhi wrote:
> Some SMP systems want to make all the possible CPUs share the clock,
> if the CPUs init frequencies aren't the same, we need to align all the
> CPUs to the same frequency while CPUs registing to avoid mismatched
> CPU's P-states.
>
> Signed-off-by: lizhuangzhi
> ---
> drivers/cpufreq/cpufreq.c |2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 8d19f7c..d00abb5 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -991,6 +991,8 @@ static int __cpufreq_add_dev(struct device *dev, struct
> subsys_interface *sif,
> * CPU because it is in the same boat. */
> policy = cpufreq_cpu_get(cpu);
> if (unlikely(policy)) {
> + /* according present policy to align all the cpus frequencies
> */
> + cpufreq_driver->target(policy, policy->cur,
> CPUFREQ_RELATION_H);
I don't really understand why is this required? CPUs sharing clocks means
that CPUs runs on the same clock line and so all of them must be running
on same frequency. So, why do we need to call this routine? policy->cur
must be the current freq here for CPU in question.
--
viresh
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[PATCH] cpufreq: Align all CPUs to the same frequency if using shared clock
Some SMP systems want to make all the possible CPUs share the clock,
if the CPUs init frequencies aren't the same, we need to align all the
CPUs to the same frequency while CPUs registing to avoid mismatched
CPU's P-states.
Signed-off-by: lizhuangzhi
---
drivers/cpufreq/cpufreq.c |2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 8d19f7c..d00abb5 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -991,6 +991,8 @@ static int __cpufreq_add_dev(struct device *dev, struct
subsys_interface *sif,
* CPU because it is in the same boat. */
policy = cpufreq_cpu_get(cpu);
if (unlikely(policy)) {
+ /* according present policy to align all the cpus frequencies */
+ cpufreq_driver->target(policy, policy->cur, CPUFREQ_RELATION_H);
cpufreq_cpu_put(policy);
return 0;
}
--
1.7.9.5
--
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the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[PATCH] cpufreq: Align all CPUs to the same frequency if using shared clock
Some SMP systems want to make all the possible CPUs share the clock,
if the CPUs init frequencies aren't the same, we need to align all the
CPUs to the same frequency while CPUs registing to avoid mismatched
CPU's P-states.
Signed-off-by: lizhuangzhi zhuangzhi...@intel.com
---
drivers/cpufreq/cpufreq.c |2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 8d19f7c..d00abb5 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -991,6 +991,8 @@ static int __cpufreq_add_dev(struct device *dev, struct
subsys_interface *sif,
* CPU because it is in the same boat. */
policy = cpufreq_cpu_get(cpu);
if (unlikely(policy)) {
+ /* according present policy to align all the cpus frequencies */
+ cpufreq_driver-target(policy, policy-cur, CPUFREQ_RELATION_H);
cpufreq_cpu_put(policy);
return 0;
}
--
1.7.9.5
--
To unsubscribe from this list: send the line unsubscribe linux-kernel in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] cpufreq: Align all CPUs to the same frequency if using shared clock
On 21 January 2014 08:35, lizhuangzhi zhuangzhi...@intel.com wrote:
Some SMP systems want to make all the possible CPUs share the clock,
if the CPUs init frequencies aren't the same, we need to align all the
CPUs to the same frequency while CPUs registing to avoid mismatched
CPU's P-states.
Signed-off-by: lizhuangzhi zhuangzhi...@intel.com
---
drivers/cpufreq/cpufreq.c |2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 8d19f7c..d00abb5 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -991,6 +991,8 @@ static int __cpufreq_add_dev(struct device *dev, struct
subsys_interface *sif,
* CPU because it is in the same boat. */
policy = cpufreq_cpu_get(cpu);
if (unlikely(policy)) {
+ /* according present policy to align all the cpus frequencies
*/
+ cpufreq_driver-target(policy, policy-cur,
CPUFREQ_RELATION_H);
I don't really understand why is this required? CPUs sharing clocks means
that CPUs runs on the same clock line and so all of them must be running
on same frequency. So, why do we need to call this routine? policy-cur
must be the current freq here for CPU in question.
--
viresh
--
To unsubscribe from this list: send the line unsubscribe linux-kernel in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
RE: [PATCH] cpufreq: Align all CPUs to the same frequency if using shared clock
Thanks for reviewing.
Sorry for make you misunderstanding, on our x86 platform, we want all the CPUs
share one policy by setting CPUFREQ_SHARED_TYPE_ALL, not share one HW clock
line.
If the CPUs work at different frequency at init stage, then while the CPUs
registering, no policy to align all the CPUs to the same frequency, this caused
some conflicts with current CPUs P-state.
For example:
CPU0: P0
CPU1: P14
CPU2: P14
CPU3: P14
During all the CPUs registering, kernel considers all the CPUs work at P0 state
because of sharing CPU0 policy, but the other three CPUs really work at P14
state,
all CPUs frequency only wait to be aligned until CPU0 state changed by governor
based on shared policy.
Best Regards
Li zhuangzhi
Android System Integration Shanghai
Tel: +86 (0)21 6116 4323
-Original Message-
From: Viresh Kumar [mailto:viresh.ku...@linaro.org]
Sent: Tuesday, January 21, 2014 2:35 PM
To: Li, Zhuangzhi
Cc: Rafael J. Wysocki; cpuf...@vger.kernel.org; linux...@vger.kernel.org; Linux
Kernel Mailing List; Liu, Chuansheng
Subject: Re: [PATCH] cpufreq: Align all CPUs to the same frequency if using
shared clock
On 21 January 2014 08:35, lizhuangzhi zhuangzhi...@intel.com wrote:
Some SMP systems want to make all the possible CPUs share the clock,
if the CPUs init frequencies aren't the same, we need to align all the
CPUs to the same frequency while CPUs registing to avoid mismatched
CPU's P-states.
Signed-off-by: lizhuangzhi zhuangzhi...@intel.com
---
drivers/cpufreq/cpufreq.c |2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 8d19f7c..d00abb5 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -991,6 +991,8 @@ static int __cpufreq_add_dev(struct device *dev, struct
subsys_interface *sif,
* CPU because it is in the same boat. */
policy = cpufreq_cpu_get(cpu);
if (unlikely(policy)) {
+ /* according present policy to align all the cpus frequencies
*/
+ cpufreq_driver-target(policy, policy-cur,
+ CPUFREQ_RELATION_H);
I don't really understand why is this required? CPUs sharing clocks means that
CPUs runs on the same clock line and so all of them must be running on same
frequency. So, why do we need to call this routine? policy-cur must be the
current freq here for CPU in question.
--
viresh
--
To unsubscribe from this list: send the line unsubscribe linux-kernel in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
