1

I'm looking into TLP and there is this setting that I don't know what does it do:

# Set Intel P-state performance: 0..100 (%)
# Limit the max/min P-state to control the power dissipation of the CPU.
# Values are stated as a percentage of the available performance.
# Requires an Intel Core i processor with intel_pstate driver.
#CPU_MIN_PERF_ON_AC=0
#CPU_MAX_PERF_ON_AC=100
#CPU_MIN_PERF_ON_BAT=0
#CPU_MAX_PERF_ON_BAT=30

What does it mean with "limit the max-min P-state"? What happen when it is 100 and what when it is 30?

2

A p-state on Intel processors is a set frequency and voltage; each processor has a number of p-states that it supports, from a low-power, low-frequency setting all the way up to its rated maximum performance. You can see how many you have by running

cat /sys/devices/system/cpu/intel_pstate/num_pstates

The min-max performance settings in TLP set lower and upper boundaries for these, the idea being that when on battery, you can reduce your system's performance in exchange for longer battery life. Setting the maximum to 100% just means that your CPU can run as fast as possible when necessary; setting it to 30% means that your CPU is limited to 30% of its performance.

The "Frequency stats" tab in PowerTOP shows how much time your CPU spends at each frequency level. i7z can show the frequency and voltage currently in use.

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