pyamsoft
commented
9 years ago Hello, thank you for your report. Before we dive into this to figure out the problem, I want to clarify two things.
First is the reading that you get from pstate-frequency compared to the reading from cpupower. pstate-frequency reads (and writes) the CPU_MIN and CPUMAX values from the files nin /sys/devices/system/cpu/cpu#/cpufreq/scaling{max,min}_freq
The numbers being outputted then, for example 825000 for the MAX should be the same as you see in the files /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq. Can you confirm this? Can you also confirm that because cpupower states that the CPU frequency is 2GHz, the machine does in fact "feel" as if it were running at that speed.
Second is the fact that, despite best efforts, pstate-frequency can not actually take complete and total control over the CPU frequencies. The frequencies are decided in the hardware itself, the pstates can only serve as "suggestions" to the driver to run at specified rates. Should the hardware choose to ignore the request to run at 25% instead of 100%, it shall. As a result, there is no way on modern hardware to guarantee that the intel_pstate driver will be able to control the cpu freqeuncies as fully as it were on the old cpufreq driver.
Also as a side note, are you running Intel's thermald?
sfauzia
pstate-frequency in powersaving mode (via "pstate-frequency -S -p auto" in my script triggered by a udev rule) perfectly sets my CPU to 800 MHz. However, upon resuming from suspend the CPU ramps up to 2.0 GHz, which rapidly depletes battery life, and running the aforementioned pstate-frequency command does not revert the computer to the original, pre-suspend state. All my other powersaving measures post suspend do function normally, so it does not appear to be a problem with the udev rule. (The pstate-frequency command should work from the cli were that the case.)
Prior to suspend, on battery power: % cpupower frequency-info analyzing CPU 0: driver: intel_pstate CPUs which run at the same hardware frequency: 0 CPUs which need to have their frequency coordinated by software: 0 maximum transition latency: 0.97 ms. hardware limits: 800 MHz - 3.30 GHz available cpufreq governors: performance, powersave current policy: frequency should be within 800 MHz and 825 MHz. The governor "powersave" may decide which speed to use within this range. current CPU frequency is 800 MHz. boost state support: Supported: yes Active: yes
% pstate-frequency -G r pstate-frequency 1.2.2[g++] pstate::CPU_DRIVER -> intel_pstate pstate::CPU_GOVERNOR -> powersave pstate::NO_TURBO -> 1 : OFF pstate::CPU_MIN -> 24% : 800000KHz pstate::CPU_MAX -> 25% : 825000KHz
After suspend, on battery power: % cpupower frequency-info analyzing CPU 0: driver: intel_pstate CPUs which run at the same hardware frequency: 0 CPUs which need to have their frequency coordinated by software: 0 maximum transition latency: 0.97 ms. hardware limits: 800 MHz - 3.30 GHz available cpufreq governors: performance, powersave current policy: frequency should be within 800 MHz and 825 MHz. The governor "powersave" may decide which speed to use within this range. current CPU frequency is 2.00 GHz (asserted by call to hardware). boost state support: Supported: yes Active: yes
% pstate-frequency -G r pstate-frequency 1.2.2[g++] pstate::CPU_DRIVER -> intel_pstate pstate::CPU_GOVERNOR -> powersave pstate::NO_TURBO -> 1 : OFF pstate::CPU_MIN -> 24% : 800000KHz pstate::CPU_MAX -> 25% : 825000KH
If there is anything else useful I may provide, please let me know. I am using a Fujjitsu T904 running on the Haswell Core i7 Processor, in ArchLinux 64-bit. Latest kernel 4.0.4-2.