Commit e4d0d7f1 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

Merge back cpufreq material for 6.9-rc1.

parents f0a0fc10 c4d61a52

Documentation/admin-guide/kernel-parameters.txt

+5 −0
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@@ -374,6 +374,11 @@ 
			  selects a performance level in this range and appropriate

			  to the current workload.



	amd_prefcore=

			[X86]

			disable

			  Disable amd-pstate preferred core.



	amijoy.map=	[HW,JOY] Amiga joystick support

			Map of devices attached to JOY0DAT and JOY1DAT

			Format: <a>,<b>

Documentation/admin-guide/pm/amd-pstate.rst

+57 −2
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@@ -300,8 +300,8 @@ platforms. The AMD P-States mechanism is the more performance and energy 
efficiency frequency management method on AMD processors.





AMD Pstate Driver Operation Modes

=================================

``amd-pstate`` Driver Operation Modes

======================================



``amd_pstate`` CPPC has 3 operation modes: autonomous (active) mode,

non-autonomous (passive) mode and guided autonomous (guided) mode.
@@ -353,6 +353,48 @@ is activated. In this mode, driver requests minimum and maximum performance 
level and the platform autonomously selects a performance level in this range

and appropriate to the current workload.



``amd-pstate`` Preferred Core

=================================



The core frequency is subjected to the process variation in semiconductors.

Not all cores are able to reach the maximum frequency respecting the

infrastructure limits. Consequently, AMD has redefined the concept of

maximum frequency of a part. This means that a fraction of cores can reach

maximum frequency. To find the best process scheduling policy for a given

scenario, OS needs to know the core ordering informed by the platform through

highest performance capability register of the CPPC interface.



``amd-pstate`` preferred core enables the scheduler to prefer scheduling on

cores that can achieve a higher frequency with lower voltage. The preferred

core rankings can dynamically change based on the workload, platform conditions,

thermals and ageing.



The priority metric will be initialized by the ``amd-pstate`` driver. The ``amd-pstate``

driver will also determine whether or not ``amd-pstate`` preferred core is

supported by the platform.



``amd-pstate`` driver will provide an initial core ordering when the system boots.

The platform uses the CPPC interfaces to communicate the core ranking to the

operating system and scheduler to make sure that OS is choosing the cores

with highest performance firstly for scheduling the process. When ``amd-pstate``

driver receives a message with the highest performance change, it will

update the core ranking and set the cpu's priority.



``amd-pstate`` Preferred Core Switch

=====================================

Kernel Parameters

-----------------



``amd-pstate`` peferred core`` has two states: enable and disable.

Enable/disable states can be chosen by different kernel parameters.

Default enable ``amd-pstate`` preferred core.



``amd_prefcore=disable``



For systems that support ``amd-pstate`` preferred core, the core rankings will

always be advertised by the platform. But OS can choose to ignore that via the

kernel parameter ``amd_prefcore=disable``.



User Space Interface in ``sysfs`` - General

===========================================
@@ -385,6 +427,19 @@ control its functionality at the system level. They are located in the 
        to the operation mode represented by that string - or to be

        unregistered in the "disable" case.



``prefcore``

	Preferred core state of the driver: "enabled" or "disabled".



	"enabled"

		Enable the ``amd-pstate`` preferred core.



	"disabled"

		Disable the ``amd-pstate`` preferred core





        This attribute is read-only to check the state of preferred core set

        by the kernel parameter.



``cpupower`` tool support for ``amd-pstate``

===============================================

arch/x86/Kconfig

+3 −2
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@@ -1054,8 +1054,9 @@ config SCHED_MC 


config SCHED_MC_PRIO

	bool "CPU core priorities scheduler support"

	depends on SCHED_MC && CPU_SUP_INTEL

	select X86_INTEL_PSTATE

	depends on SCHED_MC

	select X86_INTEL_PSTATE if CPU_SUP_INTEL

	select X86_AMD_PSTATE if CPU_SUP_AMD && ACPI

	select CPU_FREQ

	default y

	help

drivers/acpi/cppc_acpi.c

+13 −0
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@@ -1157,6 +1157,19 @@ int cppc_get_nominal_perf(int cpunum, u64 *nominal_perf) 
	return cppc_get_perf(cpunum, NOMINAL_PERF, nominal_perf);

}



/**

 * cppc_get_highest_perf - Get the highest performance register value.

 * @cpunum: CPU from which to get highest performance.

 * @highest_perf: Return address.

 *

 * Return: 0 for success, -EIO otherwise.

 */

int cppc_get_highest_perf(int cpunum, u64 *highest_perf)

{

	return cppc_get_perf(cpunum, HIGHEST_PERF, highest_perf);

}

EXPORT_SYMBOL_GPL(cppc_get_highest_perf);



/**

 * cppc_get_epp_perf - Get the epp register value.

 * @cpunum: CPU from which to get epp preference value.

drivers/acpi/processor_driver.c

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@@ -27,6 +27,7 @@ 
#define ACPI_PROCESSOR_NOTIFY_PERFORMANCE 0x80

#define ACPI_PROCESSOR_NOTIFY_POWER	0x81

#define ACPI_PROCESSOR_NOTIFY_THROTTLING	0x82

#define ACPI_PROCESSOR_NOTIFY_HIGEST_PERF_CHANGED	0x85



MODULE_AUTHOR("Paul Diefenbaugh");

MODULE_DESCRIPTION("ACPI Processor Driver");
@@ -83,6 +84,11 @@ static void acpi_processor_notify(acpi_handle handle, u32 event, void *data) 
		acpi_bus_generate_netlink_event(device->pnp.device_class,

						  dev_name(&device->dev), event, 0);

		break;

	case ACPI_PROCESSOR_NOTIFY_HIGEST_PERF_CHANGED:

		cpufreq_update_limits(pr->id);

		acpi_bus_generate_netlink_event(device->pnp.device_class,

						  dev_name(&device->dev), event, 0);

		break;

	default:

		acpi_handle_debug(handle, "Unsupported event [0x%x]\n", event);

		break;