[PATCH 2/2 V8] intel_pstate: add kernel parameter to force loading.

[PATCH 2/2 V8] intel_pstate: add kernel parameter to force loading.

[Ethan Zhao]

To force loading on Oracle Sun X86 servers, provide one kernel command line
parameter

  intel_pstate = force

For those who be aware of the risk of no power capping capabily working and
try to get better performance with this driver.

Signed-off-by: Ethan Zhao <ethan.zhao@oracle.com>
Tested-by: Alexey Kodanev <alexey.kodanev@oracle.com>
---
 v2: change to hardware vendor specific naming parameter.
 v4: refine code and doc.
 v5&v6: fix a typo in doc.
 v7: change enum PCC to PPC.
 v8: change the name of kernel command line parameter to generic one.

 Documentation/kernel-parameters.txt | 5 +++++
 drivers/cpufreq/intel_pstate.c      | 6 +++++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 479f332..7d0983e 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1446,6 +1446,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 		       disable
 		         Do not enable intel_pstate as the default
 		         scaling driver for the supported processors
+		       force
+			 Enable intel_pstate on systems where it may cause problems to
+			 happen due to conflicts with platform firmware attempting to
+			 drive P-states by itself in certain situations (for thermal 
+			 control or power capping in general or other purposes).
 
 	intremap=	[X86-64, Intel-IOMMU]
 			on	enable Interrupt Remapping (default)
diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 1bb62ca..2654e13 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -866,6 +866,7 @@ static struct cpufreq_driver intel_pstate_driver = {
 };
 
 static int __initdata no_load;
+static unsigned int  force_load;
 
 static int intel_pstate_msrs_not_valid(void)
 {
@@ -1003,7 +1004,8 @@ static bool intel_pstate_platform_pwr_mgmt_exists(void)
 			case PSS:
 				return intel_pstate_no_acpi_pss();
 			case PPC:
-				return intel_pstate_has_acpi_ppc();
+				return intel_pstate_has_acpi_ppc() &&
+					(!force_load);
 			}
 	}
 
@@ -1078,6 +1080,8 @@ static int __init intel_pstate_setup(char *str)
 
 	if (!strcmp(str, "disable"))
 		no_load = 1;
+	if (!strcmp(str, "force"))
+		force_load = 1;
 	return 0;
 }
 early_param("intel_pstate", intel_pstate_setup);
-- 
1.8.3.1

Re: [PATCH 2/2 V8] intel_pstate: add kernel parameter to force loading.

[Linda Knippers]

On 12/5/2014 4:40 AM, Ethan Zhao wrote:
> To force loading on Oracle Sun X86 servers, provide one kernel command line
> parameter
> 
>   intel_pstate = force
> 
> For those who be aware of the risk of no power capping capabily working and
> try to get better performance with this driver.
> 
> Signed-off-by: Ethan Zhao <ethan.zhao@oracle.com>
> Tested-by: Alexey Kodanev <alexey.kodanev@oracle.com>
> ---
>  v2: change to hardware vendor specific naming parameter.
>  v4: refine code and doc.
>  v5&v6: fix a typo in doc.
>  v7: change enum PCC to PPC.
>  v8: change the name of kernel command line parameter to generic one.
> 
>  Documentation/kernel-parameters.txt | 5 +++++
>  drivers/cpufreq/intel_pstate.c      | 6 +++++-
>  2 files changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> index 479f332..7d0983e 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -1446,6 +1446,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
>  		       disable
>  		         Do not enable intel_pstate as the default
>  		         scaling driver for the supported processors
> +		       force
> +			 Enable intel_pstate on systems where it may cause problems to
> +			 happen due to conflicts with platform firmware attempting to
> +			 drive P-states by itself in certain situations (for thermal 
> +			 control or power capping in general or other purposes).

I suggest something like:
			Enable intel_pstate on systems that prohibit it by
			default in favor of acpi-cpufreq.  Forcing the
			intel_pstate driver instead of acpi-cpufreq may disable
			platform features, such as thermal controls and power
			capping, that rely on ACPI p-state information being
			used by the OS and therefore should be used with care.
			This option does not work with processors that aren't
			supported by the intel_pstate driver or on platforms
			that use pcc-cpufreq instead of acpi-cpufreq.

Maybe this is too specific but I believe it is accurate.  Comments?

-- ljk

>  
>  	intremap=	[X86-64, Intel-IOMMU]
>  			on	enable Interrupt Remapping (default)
> diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
> index 1bb62ca..2654e13 100644
> --- a/drivers/cpufreq/intel_pstate.c
> +++ b/drivers/cpufreq/intel_pstate.c
> @@ -866,6 +866,7 @@ static struct cpufreq_driver intel_pstate_driver = {
>  };
>  
>  static int __initdata no_load;
> +static unsigned int  force_load;
>  
>  static int intel_pstate_msrs_not_valid(void)
>  {
> @@ -1003,7 +1004,8 @@ static bool intel_pstate_platform_pwr_mgmt_exists(void)
>  			case PSS:
>  				return intel_pstate_no_acpi_pss();
>  			case PPC:
> -				return intel_pstate_has_acpi_ppc();
> +				return intel_pstate_has_acpi_ppc() &&
> +					(!force_load);
>  			}
>  	}
>  
> @@ -1078,6 +1080,8 @@ static int __init intel_pstate_setup(char *str)
>  
>  	if (!strcmp(str, "disable"))
>  		no_load = 1;
> +	if (!strcmp(str, "force"))
> +		force_load = 1;
>  	return 0;
>  }
>  early_param("intel_pstate", intel_pstate_setup);
> 

Re: [PATCH 2/2 V8] intel_pstate: add kernel parameter to force loading.

[Rafael J. Wysocki]

On Friday, December 05, 2014 11:09:29 AM Linda Knippers wrote:
> On 12/5/2014 4:40 AM, Ethan Zhao wrote:
> > To force loading on Oracle Sun X86 servers, provide one kernel command line
> > parameter
> > 
> >   intel_pstate = force
> > 
> > For those who be aware of the risk of no power capping capabily working and
> > try to get better performance with this driver.
> > 
> > Signed-off-by: Ethan Zhao <ethan.zhao@oracle.com>
> > Tested-by: Alexey Kodanev <alexey.kodanev@oracle.com>
> > ---
> >  v2: change to hardware vendor specific naming parameter.
> >  v4: refine code and doc.
> >  v5&v6: fix a typo in doc.
> >  v7: change enum PCC to PPC.
> >  v8: change the name of kernel command line parameter to generic one.
> > 
> >  Documentation/kernel-parameters.txt | 5 +++++
> >  drivers/cpufreq/intel_pstate.c      | 6 +++++-
> >  2 files changed, 10 insertions(+), 1 deletion(-)
> > 
> > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> > index 479f332..7d0983e 100644
> > --- a/Documentation/kernel-parameters.txt
> > +++ b/Documentation/kernel-parameters.txt
> > @@ -1446,6 +1446,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
> >  		       disable
> >  		         Do not enable intel_pstate as the default
> >  		         scaling driver for the supported processors
> > +		       force
> > +			 Enable intel_pstate on systems where it may cause problems to
> > +			 happen due to conflicts with platform firmware attempting to
> > +			 drive P-states by itself in certain situations (for thermal 
> > +			 control or power capping in general or other purposes).
> 
> I suggest something like:
> 			Enable intel_pstate on systems that prohibit it by
> 			default in favor of acpi-cpufreq.  Forcing the
> 			intel_pstate driver instead of acpi-cpufreq may disable
> 			platform features, such as thermal controls and power
> 			capping, that rely on ACPI p-state information being
> 			used by the OS and therefore should be used with care.
> 			This option does not work with processors that aren't
> 			supported by the intel_pstate driver or on platforms
> 			that use pcc-cpufreq instead of acpi-cpufreq.
> 
> Maybe this is too specific but I believe it is accurate.  Comments?

Looks good to me, thanks!


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.

Re: [PATCH 2/2 V8] intel_pstate: add kernel parameter to force loading.

[ethan]

Linda，

> 在 2014年12月6日，00:09，Linda Knippers <linda.knippers@hp.com> 写道：
> 
>> On 12/5/2014 4:40 AM, Ethan Zhao wrote:
>> To force loading on Oracle Sun X86 servers, provide one kernel command line
>> parameter
>> 
>>  intel_pstate = force
>> 
>> For those who be aware of the risk of no power capping capabily working and
>> try to get better performance with this driver.
>> 
>> Signed-off-by: Ethan Zhao <ethan.zhao@oracle.com>
>> Tested-by: Alexey Kodanev <alexey.kodanev@oracle.com>
>> ---
>> v2: change to hardware vendor specific naming parameter.
>> v4: refine code and doc.
>> v5&v6: fix a typo in doc.
>> v7: change enum PCC to PPC.
>> v8: change the name of kernel command line parameter to generic one.
>> 
>> Documentation/kernel-parameters.txt | 5 +++++
>> drivers/cpufreq/intel_pstate.c      | 6 +++++-
>> 2 files changed, 10 insertions(+), 1 deletion(-)
>> 
>> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
>> index 479f332..7d0983e 100644
>> --- a/Documentation/kernel-parameters.txt
>> +++ b/Documentation/kernel-parameters.txt
>> @@ -1446,6 +1446,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
>>               disable
>>                 Do not enable intel_pstate as the default
>>                 scaling driver for the supported processors
>> +               force
>> +             Enable intel_pstate on systems where it may cause problems to
>> +             happen due to conflicts with platform firmware attempting to
>> +             drive P-states by itself in certain situations (for thermal 
>> +             control or power capping in general or other purposes).
> 
> I suggest something like:
>            Enable intel_pstate on systems that prohibit it by
>            default in favor of acpi-cpufreq.  Forcing the
>            intel_pstate driver instead of acpi-cpufreq may disable
>            platform features, such as thermal controls and power
>            capping, that rely on ACPI p-state information being
                                                         P-States 
>             Used by the OS and therefore should be used with care.
               Indicated to OSPM                                                   caution 
>            This option does not work with processors that aren't
>            supported by the intel_pstate driver or on platforms
>            that use pcc-cpufreq instead of acpi-cpufreq.
> 
> Maybe this is too specific but I believe it is accurate.  Comments?
> 

Looks better to me, except some words commented. 

Thanks,
Ethan
> -- ljk
> 
>> 
>>    intremap=    [X86-64, Intel-IOMMU]
>>            on    enable Interrupt Remapping (default)
>> diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
>> index 1bb62ca..2654e13 100644
>> --- a/drivers/cpufreq/intel_pstate.c
>> +++ b/drivers/cpufreq/intel_pstate.c
>> @@ -866,6 +866,7 @@ static struct cpufreq_driver intel_pstate_driver = {
>> };
>> 
>> static int __initdata no_load;
>> +static unsigned int  force_load;
>> 
>> static int intel_pstate_msrs_not_valid(void)
>> {
>> @@ -1003,7 +1004,8 @@ static bool intel_pstate_platform_pwr_mgmt_exists(void)
>>            case PSS:
>>                return intel_pstate_no_acpi_pss();
>>            case PPC:
>> -                return intel_pstate_has_acpi_ppc();
>> +                return intel_pstate_has_acpi_ppc() &&
>> +                    (!force_load);
>>            }
>>    }
>> 
>> @@ -1078,6 +1080,8 @@ static int __init intel_pstate_setup(char *str)
>> 
>>    if (!strcmp(str, "disable"))
>>        no_load = 1;
>> +    if (!strcmp(str, "force"))
>> +        force_load = 1;
>>    return 0;
>> }
>> early_param("intel_pstate", intel_pstate_setup);
> 

Re: [PATCH 2/2 V8] intel_pstate: add kernel parameter to force loading.

[Linda Knippers]

On 12/5/2014 9:16 PM, ethan wrote:
> Linda，
> 
>> 在 2014年12月6日，00:09，Linda Knippers <linda.knippers@hp.com> 写道：
>>
>>> On 12/5/2014 4:40 AM, Ethan Zhao wrote:
>>> To force loading on Oracle Sun X86 servers, provide one kernel command line
>>> parameter
>>>
>>>  intel_pstate = force
>>>
>>> For those who be aware of the risk of no power capping capabily working and
>>> try to get better performance with this driver.
>>>
>>> Signed-off-by: Ethan Zhao <ethan.zhao@oracle.com>
>>> Tested-by: Alexey Kodanev <alexey.kodanev@oracle.com>
>>> ---
>>> v2: change to hardware vendor specific naming parameter.
>>> v4: refine code and doc.
>>> v5&v6: fix a typo in doc.
>>> v7: change enum PCC to PPC.
>>> v8: change the name of kernel command line parameter to generic one.
>>>
>>> Documentation/kernel-parameters.txt | 5 +++++
>>> drivers/cpufreq/intel_pstate.c      | 6 +++++-
>>> 2 files changed, 10 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
>>> index 479f332..7d0983e 100644
>>> --- a/Documentation/kernel-parameters.txt
>>> +++ b/Documentation/kernel-parameters.txt
>>> @@ -1446,6 +1446,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
>>>               disable
>>>                 Do not enable intel_pstate as the default
>>>                 scaling driver for the supported processors
>>> +               force
>>> +             Enable intel_pstate on systems where it may cause problems to
>>> +             happen due to conflicts with platform firmware attempting to
>>> +             drive P-states by itself in certain situations (for thermal 
>>> +             control or power capping in general or other purposes).
>>
>> I suggest something like:
>>            Enable intel_pstate on systems that prohibit it by
>>            default in favor of acpi-cpufreq.  Forcing the
>>            intel_pstate driver instead of acpi-cpufreq may disable
>>            platform features, such as thermal controls and power
>>            capping, that rely on ACPI p-state information being
>                                                          P-States 
>>             Used by the OS and therefore should be used with care.
>                Indicated to OSPM                                                   caution 
>>            This option does not work with processors that aren't
>>            supported by the intel_pstate driver or on platforms
>>            that use pcc-cpufreq instead of acpi-cpufreq.
>>
>> Maybe this is too specific but I believe it is accurate.  Comments?
>>
> 
> Looks better to me, except some words commented. 

Your suggestions look fine to me.

-- ljk
> 
> Thanks,
> Ethan
>> -- ljk
>>
>>>
>>>    intremap=    [X86-64, Intel-IOMMU]
>>>            on    enable Interrupt Remapping (default)
>>> diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
>>> index 1bb62ca..2654e13 100644
>>> --- a/drivers/cpufreq/intel_pstate.c
>>> +++ b/drivers/cpufreq/intel_pstate.c
>>> @@ -866,6 +866,7 @@ static struct cpufreq_driver intel_pstate_driver = {
>>> };
>>>
>>> static int __initdata no_load;
>>> +static unsigned int  force_load;
>>>
>>> static int intel_pstate_msrs_not_valid(void)
>>> {
>>> @@ -1003,7 +1004,8 @@ static bool intel_pstate_platform_pwr_mgmt_exists(void)
>>>            case PSS:
>>>                return intel_pstate_no_acpi_pss();
>>>            case PPC:
>>> -                return intel_pstate_has_acpi_ppc();
>>> +                return intel_pstate_has_acpi_ppc() &&
>>> +                    (!force_load);
>>>            }
>>>    }
>>>
>>> @@ -1078,6 +1080,8 @@ static int __init intel_pstate_setup(char *str)
>>>
>>>    if (!strcmp(str, "disable"))
>>>        no_load = 1;
>>> +    if (!strcmp(str, "force"))
>>> +        force_load = 1;
>>>    return 0;
>>> }
>>> early_param("intel_pstate", intel_pstate_setup);
>>
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