cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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fam15h_power.rst (3641B)

      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".