Documentation/hwmon/fam15h_power.rst

Source file repositories/reference/linux-study-clean/Documentation/hwmon/fam15h_power.rst

File Facts

System
Linux kernel
Corpus path
Documentation/hwmon/fam15h_power.rst
Extension
.rst
Size
3641 bytes
Lines
132
Domain
Support Tooling And Documentation
Bucket
Documentation
Inferred role
Support Tooling And Documentation: documentation
Status
atlas-only

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

Kernel driver fam15h_power
==========================

Supported chips:

* AMD Family 15h Processors

* AMD Family 16h Processors

  Prefix: 'fam15h_power'

  Addresses scanned: PCI space

  Datasheets:

  - BIOS and Kernel Developer's Guide (BKDG) For AMD Family 15h Processors
  - BIOS and Kernel Developer's Guide (BKDG) For AMD Family 16h Processors
  - AMD64 Architecture Programmer's Manual Volume 2: System Programming

Author: Andreas Herrmann <herrmann.der.user@googlemail.com>

Description
-----------

1) Processor TDP (Thermal design power)

Given a fixed frequency and voltage, the power consumption of a
processor varies based on the workload being executed. Derated power
is the power consumed when running a specific application. Thermal
design power (TDP) is an example of derated power.

This driver permits reading of registers providing power information
of AMD Family 15h and 16h processors via TDP algorithm.

For AMD Family 15h and 16h processors the following power values can
be calculated using different processor northbridge function
registers:

* BasePwrWatts:
    Specifies in watts the maximum amount of power
    consumed by the processor for NB and logic external to the core.

* ProcessorPwrWatts:
    Specifies in watts the maximum amount of power
    the processor can support.
* CurrPwrWatts:
    Specifies in watts the current amount of power being
    consumed by the processor.

This driver provides ProcessorPwrWatts and CurrPwrWatts:

* power1_crit (ProcessorPwrWatts)
* power1_input (CurrPwrWatts)

On multi-node processors the calculated value is for the entire
package and not for a single node. Thus the driver creates sysfs
attributes only for internal node0 of a multi-node processor.

2) Accumulated Power Mechanism

This driver also introduces an algorithm that should be used to
calculate the average power consumed by a processor during a
measurement interval Tm. The feature of accumulated power mechanism is
indicated by CPUID Fn8000_0007_EDX[12].

* Tsample:
	compute unit power accumulator sample period

* Tref:
	the PTSC counter period

Annotation

Implementation Notes