[v3] Adjustments for preferred core detection

[PATCH v3 10/11] cpufreq: amd-pstate: Add documentation for `amd_pstate_hw_prefcore`

Posted by Mario Limonciello 1 year, 3 months ago

From: Mario Limonciello <mario.limonciello@amd.com>

Explain that the sysfs file represents both preferred core being
enabled by the user and supported by the hardware.

Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
v2->v3:
 * Add tag
---
 Documentation/admin-guide/pm/amd-pstate.rst | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst
index e13915c540648..d5c050ea390dc 100644
--- a/Documentation/admin-guide/pm/amd-pstate.rst
+++ b/Documentation/admin-guide/pm/amd-pstate.rst
@@ -263,6 +263,11 @@ lowest non-linear performance in `AMD CPPC Performance Capability
 <perf_cap_>`_.)
 This attribute is read-only.
 
+``amd_pstate_hw_prefcore``
+
+Whether the platform supports the preferred core feature and it has been
+enabled. This attribute is read-only.
+
 ``energy_performance_available_preferences``
 
 A list of all the supported EPP preferences that could be used for
-- 
2.43.0

Re: [PATCH v3 10/11] cpufreq: amd-pstate: Add documentation for `amd_pstate_hw_prefcore`

Posted by Russell Haley 1 year, 3 months ago

On 9/5/24 11:30 AM, Mario Limonciello wrote:
> From: Mario Limonciello <mario.limonciello@amd.com>
> 
> Explain that the sysfs file represents both preferred core being
> enabled by the user and supported by the hardware.
> 
> Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> ---
> v2->v3:
>  * Add tag
> ---
>  Documentation/admin-guide/pm/amd-pstate.rst | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst
> index e13915c540648..d5c050ea390dc 100644
> --- a/Documentation/admin-guide/pm/amd-pstate.rst
> +++ b/Documentation/admin-guide/pm/amd-pstate.rst
> @@ -263,6 +263,11 @@ lowest non-linear performance in `AMD CPPC Performance Capability
>  <perf_cap_>`_.)
>  This attribute is read-only.
>  
> +``amd_pstate_hw_prefcore``
> +
> +Whether the platform supports the preferred core feature and it has been
> +enabled. This attribute is read-only.
> +
>  ``energy_performance_available_preferences``
>  
>  A list of all the supported EPP preferences that could be used for

I notice I am confused. If the attribute is read only, how can it be
enabled by the user?

Re: [PATCH v3 10/11] cpufreq: amd-pstate: Add documentation for `amd_pstate_hw_prefcore`

Posted by Mario Limonciello 1 year, 3 months ago

On 9/10/2024 05:19, Russell Haley wrote:
> On 9/5/24 11:30 AM, Mario Limonciello wrote:
>> From: Mario Limonciello <mario.limonciello@amd.com>
>>
>> Explain that the sysfs file represents both preferred core being
>> enabled by the user and supported by the hardware.
>>
>> Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
>> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
>> ---
>> v2->v3:
>>   * Add tag
>> ---
>>   Documentation/admin-guide/pm/amd-pstate.rst | 5 +++++
>>   1 file changed, 5 insertions(+)
>>
>> diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst
>> index e13915c540648..d5c050ea390dc 100644
>> --- a/Documentation/admin-guide/pm/amd-pstate.rst
>> +++ b/Documentation/admin-guide/pm/amd-pstate.rst
>> @@ -263,6 +263,11 @@ lowest non-linear performance in `AMD CPPC Performance Capability
>>   <perf_cap_>`_.)
>>   This attribute is read-only.
>>   
>> +``amd_pstate_hw_prefcore``
>> +
>> +Whether the platform supports the preferred core feature and it has been
>> +enabled. This attribute is read-only.
>> +
>>   ``energy_performance_available_preferences``
>>   
>>   A list of all the supported EPP preferences that could be used for
> 
> I notice I am confused. If the attribute is read only, how can it be
> enabled by the user?

It is enabled by default.  It can be disabled by the user via the kernel 
command line:

amd_prefcore=disable

This is documented separately in kernel-parameters.txt.