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Based on kernel version 4.7.2. Page generated on 2016-08-22 22:46 EST.

1	Kernel driver fam15h_power
2	==========================
3	
4	Supported chips:
5	* AMD Family 15h Processors
6	* AMD Family 16h Processors
7	
8	  Prefix: 'fam15h_power'
9	  Addresses scanned: PCI space
10	  Datasheets:
11	  BIOS and Kernel Developer's Guide (BKDG) For AMD Family 15h Processors
12	  BIOS and Kernel Developer's Guide (BKDG) For AMD Family 16h Processors
13	  AMD64 Architecture Programmer's Manual Volume 2: System Programming
14	
15	Author: Andreas Herrmann <herrmann.der.user@googlemail.com>
16	
17	Description
18	-----------
19	
20	1) Processor TDP (Thermal design power)
21	
22	Given a fixed frequency and voltage, the power consumption of a
23	processor varies based on the workload being executed. Derated power
24	is the power consumed when running a specific application. Thermal
25	design power (TDP) is an example of derated power.
26	
27	This driver permits reading of registers providing power information
28	of AMD Family 15h and 16h processors via TDP algorithm.
29	
30	For AMD Family 15h and 16h processors the following power values can
31	be calculated using different processor northbridge function
32	registers:
33	
34	* BasePwrWatts: Specifies in watts the maximum amount of power
35	  consumed by the processor for NB and logic external to the core.
36	* ProcessorPwrWatts: Specifies in watts the maximum amount of power
37	  the processor can support.
38	* CurrPwrWatts: Specifies in watts the current amount of power being
39	  consumed by the processor.
40	
41	This driver provides ProcessorPwrWatts and CurrPwrWatts:
42	* power1_crit (ProcessorPwrWatts)
43	* power1_input (CurrPwrWatts)
44	
45	On multi-node processors the calculated value is for the entire
46	package and not for a single node. Thus the driver creates sysfs
47	attributes only for internal node0 of a multi-node processor.
48	
49	2) Accumulated Power Mechanism
50	
51	This driver also introduces an algorithm that should be used to
52	calculate the average power consumed by a processor during a
53	measurement interval Tm. The feature of accumulated power mechanism is
54	indicated by CPUID Fn8000_0007_EDX[12].
55	
56	* Tsample: compute unit power accumulator sample period
57	* Tref: the PTSC counter period
58	* PTSC: performance timestamp counter
59	* N: the ratio of compute unit power accumulator sample period to the
60	  PTSC period
61	* Jmax: max compute unit accumulated power which is indicated by
62	  MaxCpuSwPwrAcc MSR C001007b
63	* Jx/Jy: compute unit accumulated power which is indicated by
64	  CpuSwPwrAcc MSR C001007a
65	* Tx/Ty: the value of performance timestamp counter which is indicated
66	  by CU_PTSC MSR C0010280
67	* PwrCPUave: CPU average power
68	
69	i. Determine the ratio of Tsample to Tref by executing CPUID Fn8000_0007.
70		N = value of CPUID Fn8000_0007_ECX[CpuPwrSampleTimeRatio[15:0]].
71	
72	ii. Read the full range of the cumulative energy value from the new
73	MSR MaxCpuSwPwrAcc.
74		Jmax = value returned.
75	iii. At time x, SW reads CpuSwPwrAcc MSR and samples the PTSC.
76		Jx = value read from CpuSwPwrAcc and Tx = value read from
77	PTSC.
78	
79	iv. At time y, SW reads CpuSwPwrAcc MSR and samples the PTSC.
80		Jy = value read from CpuSwPwrAcc and Ty = value read from
81	PTSC.
82	
83	v. Calculate the average power consumption for a compute unit over
84	time period (y-x). Unit of result is uWatt.
85		if (Jy < Jx) // Rollover has occurred
86			Jdelta = (Jy + Jmax) - Jx
87		else
88			Jdelta = Jy - Jx
89		PwrCPUave = N * Jdelta * 1000 / (Ty - Tx)
90	
91	This driver provides PwrCPUave and interval(default is 10 millisecond
92	and maximum is 1 second):
93	* power1_average (PwrCPUave)
94	* power1_average_interval (Interval)
95	
96	The power1_average_interval can be updated at /etc/sensors3.conf file
97	as below:
98	
99	chip "fam15h_power-*"
100		set power1_average_interval 0.01
101	
102	Then save it with "sensors -s".
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