1Kernel driver fam15h_power
  2==========================
  3
  4Supported chips:
  5
  6* AMD Family 15h Processors
  7
  8* AMD Family 16h Processors
  9
 10  Prefix: 'fam15h_power'
 11
 12  Addresses scanned: PCI space
 13
 14  Datasheets:
 15
 16  - BIOS and Kernel Developer's Guide (BKDG) For AMD Family 15h Processors
 17  - BIOS and Kernel Developer's Guide (BKDG) For AMD Family 16h Processors
 18  - AMD64 Architecture Programmer's Manual Volume 2: System Programming
 19
 20Author: Andreas Herrmann <herrmann.der.user@googlemail.com>
 21
 22Description
 23-----------
 24
 251) Processor TDP (Thermal design power)
 26
 27Given a fixed frequency and voltage, the power consumption of a
 28processor varies based on the workload being executed. Derated power
 29is the power consumed when running a specific application. Thermal
 30design power (TDP) is an example of derated power.
 31
 32This driver permits reading of registers providing power information
 33of AMD Family 15h and 16h processors via TDP algorithm.
 34
 35For AMD Family 15h and 16h processors the following power values can
 36be calculated using different processor northbridge function
 37registers:
 38
 39* BasePwrWatts:
 40    Specifies in watts the maximum amount of power
 41    consumed by the processor for NB and logic external to the core.
 42
 43* ProcessorPwrWatts:
 44    Specifies in watts the maximum amount of power
 45    the processor can support.
 46* CurrPwrWatts:
 47    Specifies in watts the current amount of power being
 48    consumed by the processor.
 49
 50This driver provides ProcessorPwrWatts and CurrPwrWatts:
 51
 52* power1_crit (ProcessorPwrWatts)
 53* power1_input (CurrPwrWatts)
 54
 55On multi-node processors the calculated value is for the entire
 56package and not for a single node. Thus the driver creates sysfs
 57attributes only for internal node0 of a multi-node processor.
 58
 592) Accumulated Power Mechanism
 60
 61This driver also introduces an algorithm that should be used to
 62calculate the average power consumed by a processor during a
 63measurement interval Tm. The feature of accumulated power mechanism is
 64indicated by CPUID Fn8000_0007_EDX[12].
 65
 66* Tsample:
 67	compute unit power accumulator sample period
 68
 69* Tref:
 70	the PTSC counter period
 71
 72* PTSC:
 73	performance timestamp counter
 74
 75* N:
 76	the ratio of compute unit power accumulator sample period to the
 77	PTSC period
 78
 79* Jmax:
 80	max compute unit accumulated power which is indicated by
 81	MaxCpuSwPwrAcc MSR C001007b
 82
 83* Jx/Jy:
 84	compute unit accumulated power which is indicated by
 85	CpuSwPwrAcc MSR C001007a
 86* Tx/Ty:
 87	the value of performance timestamp counter which is indicated
 88	by CU_PTSC MSR C0010280
 89
 90* PwrCPUave:
 91	CPU average power
 92
 93i. Determine the ratio of Tsample to Tref by executing CPUID Fn8000_0007.
 94
 95	N = value of CPUID Fn8000_0007_ECX[CpuPwrSampleTimeRatio[15:0]].
 96
 97ii. Read the full range of the cumulative energy value from the new
 98    MSR MaxCpuSwPwrAcc.
 99
100	Jmax = value returned.
101
102iii. At time x, SW reads CpuSwPwrAcc MSR and samples the PTSC.
103
104	Jx = value read from CpuSwPwrAcc and Tx = value read from PTSC.
105
106iv. At time y, SW reads CpuSwPwrAcc MSR and samples the PTSC.
107
108	Jy = value read from CpuSwPwrAcc and Ty = value read from PTSC.
109
110v. Calculate the average power consumption for a compute unit over
111   time period (y-x). Unit of result is uWatt::
112
113	if (Jy < Jx) // Rollover has occurred
114		Jdelta = (Jy + Jmax) - Jx
115	else
116		Jdelta = Jy - Jx
117	PwrCPUave = N * Jdelta * 1000 / (Ty - Tx)
118
119This driver provides PwrCPUave and interval(default is 10 millisecond
120and maximum is 1 second):
121
122* power1_average (PwrCPUave)
123* power1_average_interval (Interval)
124
125The power1_average_interval can be updated at /etc/sensors3.conf file
126as below:
127
128chip `fam15h_power-*`
129	set power1_average_interval 0.01
130
131Then save it with "sensors -s".