Hi all,

I have a question related to intel_pstate driver and CPU frequency scaling. I have multiple CPUs (i9-9900K, i3-8300T) and the linux kernel/intel_state driver handle them differently. I'm building a low power NAS using Intel i3-8300T CPU and I would like to configure it to a power saving mode. Its frequency range is 800MHz-3200MHz but the it will not go down below 1600MHz (Debian 10, Linux Kernel 5.6). Intel Speed Step and Speed Shift is enabled in the BIOS. I do not understand why intel_pstate driver does not let the CPU to reach the 800HMz and to consume less power. Is it a bug or works as planned?

In a different PC my Intel i9-9900K will scale down to 800MHz.

I read a lot about intel_pstate driver (many forum members said it is still buggy) and my understanding is that this is still the most efficient CPU scaling solution. Other drivers (acpi_freq etc.) are slower.

Any help would be appreciated.
Thanks,

Peter


Values from /sys filesystem - Intel i3-8300T CPU

/sys/devices/system/cpu/intel_pstate
hwp_dynamic_boost - 0
max_perf_pct - 100
min_perf_pct - 25
no_turbo - 1
num_pstates - 25
status - active
turbo_pct - 0

/sys/devices/system/cpu/cpufreq/policy0
affected_cpus - 0
base_frequency - 3200000
cpuinfo_max_freq - 3200000
cpuinfo_min_freq - 800000
cpuinfo_transition_latency - 0
energy_performance_available_preferences - default performance balance_performan ce balance_power power
energy_performance_preference - balance_performance
related_cpus - 0
scaling_available_governors - performance powersave
scaling_cur_freq - 1599996
scaling_driver - intel_pstate
scaling_governor - powersave
scaling_max_freq - 3200000
scaling_min_freq - 800000
scaling_setspeed - <unsupported>