mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-21 16:29:59 +00:00
![Huang Rui](/assets/img/avatar_default.png)
This patch adds the description to explain the TDP reporting mechanism and accumulated power algorithm. Signed-off-by: Huang Rui <ray.huang@amd.com> Cc: Borislav Petkov <bp@alien8.de> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
102 lines
3.5 KiB
Text
102 lines
3.5 KiB
Text
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
|
|
* PTSC: performance timestamp counter
|
|
* N: the ratio of compute unit power accumulator sample period to the
|
|
PTSC period
|
|
* Jmax: max compute unit accumulated power which is indicated by
|
|
MaxCpuSwPwrAcc MSR C001007b
|
|
* Jx/Jy: compute unit accumulated power which is indicated by
|
|
CpuSwPwrAcc MSR C001007a
|
|
* Tx/Ty: the value of performance timestamp counter which is indicated
|
|
by CU_PTSC MSR C0010280
|
|
* PwrCPUave: CPU average power
|
|
|
|
i. Determine the ratio of Tsample to Tref by executing CPUID Fn8000_0007.
|
|
N = value of CPUID Fn8000_0007_ECX[CpuPwrSampleTimeRatio[15:0]].
|
|
|
|
ii. Read the full range of the cumulative energy value from the new
|
|
MSR MaxCpuSwPwrAcc.
|
|
Jmax = value returned.
|
|
iii. At time x, SW reads CpuSwPwrAcc MSR and samples the PTSC.
|
|
Jx = value read from CpuSwPwrAcc and Tx = value read from
|
|
PTSC.
|
|
|
|
iv. At time y, SW reads CpuSwPwrAcc MSR and samples the PTSC.
|
|
Jy = value read from CpuSwPwrAcc and Ty = value read from
|
|
PTSC.
|
|
|
|
v. Calculate the average power consumption for a compute unit over
|
|
time period (y-x). Unit of result is uWatt.
|
|
if (Jy < Jx) // Rollover has occurred
|
|
Jdelta = (Jy + Jmax) - Jx
|
|
else
|
|
Jdelta = Jy - Jx
|
|
PwrCPUave = N * Jdelta * 1000 / (Ty - Tx)
|
|
|
|
This driver provides PwrCPUave and interval(default is 10 millisecond
|
|
and maximum is 1 second):
|
|
* power1_average (PwrCPUave)
|
|
* power1_average_interval (Interval)
|
|
|
|
The power1_average_interval can be updated at /etc/sensors3.conf file
|
|
as below:
|
|
|
|
chip "fam15h_power-*"
|
|
set power1_average_interval 0.01
|
|
|
|
Then save it with "sensors -s".
|