cpufreq question

Hi,

I just updatet my kernel and I am now a little bit confused about
cpufreq. For example setting dev.cpu.0.freq=600.
It could use, acpi_perf or est for that. (I think in this case they do
the same). It could also use acpi_throttle or acpi_perf for that. Even
changing speed to 1200 Mhz and then using 50% throttling would be
possible.

I have not read kernel source so far.

sudo sysctl dev.cpu
dev.cpu.0.%desc: ACPI CPU (3 Cx states)
dev.cpu.0.%driver: cpu
dev.cpu.0.%location: handle=\_PR_.CPU_
dev.cpu.0.%pnpinfo: _HID=none _UID=0
dev.cpu.0.%parent: acpi0
dev.cpu.0.freq: 1600
dev.cpu.0.freq_levels: 1600/-1 1600/24500 1400/-1 1400/21000 1225/-1 1200/-1 1200/17000 1050/-1 1000/-1 1000/13500 900/-1 875/-1 800/-1 800/9500 750/-1 700/-1 656/-1 625/-1 600/-1 600/6000 562/-1 525/-1 500/-1 450/-1 400/-1 375/-1 350/-1 300/-1 250/-1 225/-1 200/-1 175/-1 150/-1 125/-1 100/-1 75/-1 50/-1 25/-1

dev.est.0.%desc: Enhanced SpeedStep Frequency Control
dev.est.0.%driver: est
dev.est.0.%parent: cpu0
dev.est.0.freq_settings: 1600/-1 1400/-1 1200/-1 1000/-1 800/-1 600/-1

dev.p4tcc.0.%desc: CPU Frequency Thermal Control
dev.p4tcc.0.%driver: p4tcc
dev.p4tcc.0.%parent: cpu0
dev.p4tcc.0.freq_settings: 10000/-1 8750/-1 7500/-1 6250/-1 5000/-1 3750/-1 2500/-1 1250/-1

dev.acpi_throttle.0.%desc: ACPI CPU Throttling
dev.acpi_throttle.0.%driver: acpi_throttle
dev.acpi_throttle.0.%parent: cpu0
dev.acpi_throttle.0.freq_settings: 10000/-1 8750/-1 7500/-1 6250/-1 5000/-1 3750/-1 2500/-1 1250/-1

dev.acpi_perf.0.%desc: ACPI CPU Frequency Control
dev.acpi_perf.0.%driver: acpi_perf
dev.acpi_perf.0.%parent: cpu0
dev.acpi_perf.0.freq_settings: 1600/24500 1400/21000 1200/17000 1000/13500 800/9500 600/6000

dmesg:

cpu0: <ACPI CPU (3 Cx states)> on acpi0
est0: <Enhanced SpeedStep Frequency Control> on cpu0
p4tcc0: <CPU Frequency Thermal Control> on cpu0
acpi_perf0: <ACPI CPU Frequency Control> on cpu0
acpi_throttle0: <ACPI CPU Throttling> on cpu0
acpi_throttle0: P_CNT from P_BLK 0x1010


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