Improving battery life, TLP and Intel pstate

KitsuneNoBaka · May 23, 2025, 7:18pm

intel_pstate don’t work because patch for xen wasn’t committed for few years now

Intel CPU Frequency Scaling Broken

opened 10:23PM - 12 Dec 18 UTC

C: Xen P: major r4.1-buster-stable hardware support r4.1-bullseye-stable r4.1-dom0-stable needs diagnosis pr submitted r4.1-centos-stream8-cur-test r4.1-bookworm-stable r4.2-host-cur-test affects-4.1 affects-4.2

### Qubes OS version: R4.0 ### Affected component(s): intel_pstate ac…pi-cpufreq xenpm --- ### Steps to reproduce the behavior: Tested on: - Lenovo T480s - Lenovo X1 Carbon Gen. 6 - Huawei Matebook X Pro. All with Intel i7-8550U. Latest BIOS revisions for the respective systems as of Dec. 2018 Kernel: 4.19.2-3.pvops.qubes.x86_64. EFI install. In dom0, `sudo xenpm get-cpufreq-para` ### Expected behavior: The processor is rated at 1.8 GHz (4.0 turbo), so we would expect to see appropriate scaling in that range, available frequencies from 1800000 - 4000000. Further, we would expect to see `scaling_driver = intel_pstate`. ### Actual behavior: The CPU frequencies do not scale correctly. Why? Frequencies are pinned at 2 GHz max, 400 MHz min, across all cores. ``` # xenpm cpu-freq-para ... cpu id : 0 affected_cpus : 0 cpuinfo frequency : max [2001000] min [400000] cur [2001000] scaling_driver : acpi-cpufreq scaling_avail_gov : userspace performance powersave ondemand current_governor : ondemand ondemand specific : sampling_rate : max [10000000] min [10000] cur [20000] up_threshold : 80 scaling_avail_freq : 2001000 2000000 1900000 1800000 1700000 1500000 1400000 1300000 1200000 1100000 1000000 800000 700000 600000 500000 *400000 scaling frequency : max [2001000] min [400000] cur [400000] turbo mode : enabled ... ``` Confirmed with `watch -n1 "cat /proc/cpuinfo | grep \"[c]pu MHz\""` `xenpm set-scaling-maxfreq` and `-minfreq` have no effect. `xenpm get-cpufreq-states` shows 16 total/usable P-states. Changing the governor to `performance` has no effect. Default is `ondemand` `dmidecode` reports a max of 2 GHz on the Lenovos, and an apparently erroneous speed on the Huawei (~ 8 GHz). ``` # dmidecode | grep -i speed Speed: 2400 MT/s Configured Clock Speed: 2400 MT/s Speed: 2400 MT/s Configured Clock Speed: 2400 MT/s Speed: Unknown Speed: Unknown Speed: Unknown Max Speed: 2000 MHz Current Speed: 1800 MHz ``` The `scaling_driver` is legacy `acpi-cpufreq`. Interestingly, `intel_pstate` can be seen initializing during boot, but it does not take over handling anything. Attempting to `blacklist acpi-cpufreq` in `modprobe.d` has no effect. ``` # dmesg | grep pstate [ 5.067624] intel_pstate: Intel P-state driver initializing ``` `/sys/devices/system/cpu/intel_pstate/` contains the expected attributes, but as mentioned in the "related issue" linked below, `no_turbo`, `num_pstates`, and `turbo_pct` error `Resource temporarily unavailable`. `/sys/devices/system/cpu/intel_pstate/status` always returns `off`, and does not respond to `echo "active" >`. This behavior has been tested with various kernel command line parameters, including `intel_pstate=force`, `intel_pstate=disabled`, `intel_pstate=no_hwp`, `intel_pstate=enable` with no change in performance aside from `../cpu/intel_pstate/` attributes disappearing when `no_hwp` or `disabled` were in effect. Also tried `processor.ignore_ppc=1`. Strangely, none of the appropriate attributes for `cpufreq` exist in `/sys/devices/system/cpu/cpu*/`. ``` # ls /sys/devices/system/cpu/cpu0/ acpi_cppc driver hotplug power topology cache firmware_node node0 subsystem uevent ``` `lsmod | grep cpufreq` shows no results, trying to `modprobe acpi-cpufreq` or `cpufreq-xen` returns errors. `xen_acpi_processor` is loaded. ``` # modprobe acpi-cpufreq modprobe: ERROR: could not insert 'acpi_cpufreq': No such device # modprobe cpufreq-xen modprobe: FATAL: Module cpufreq-xen not found in directory /lib/modules/4.19.2-3.pvops.qubes.x86_64 ``` `cpupower frequency-info` is completely unresponsive, with zero information available about the processor. ``` analyzing CPU 0: no or unknown cpufreq driver is active on this CPU CPUs which run at the same hardware frequency: Not Available CPUs which need to have their frequency coordinated by software: Not Available maximum transition latency: Cannot determine or is not supported. Not Available available cpufreq governors: Not Available Unable to determine current policy current CPU frequency: Unable to call hardware current CPU frequency: Unable to call to kernel boost state support: Supported: yes Active: yes ``` Though it shouldn't have any effect, testing was attempted with `smt=on` and `off`, and `Hyperthreading` enabled/disabled in the BIOS appropriately. Testing was also performed while toggling various BIOS settings. - enable/disable `Intel SpeedStep` - power settings at `Maximum Performance` vs. `Balanced` It does not appear to be a thermal throttling issue, with idle ~ 37*C and under load ~60*C observed consistently. `tlp` was tested with no effect on the frequency scaling, regardless of being enabled or disabled. `tlp-stat` yields minimal additional info, with what seems to be an outdated recommendation for the Lenovos to install `tp-smapi kernel modules`, that are in fact deprecated in favor of `thinkpad_acpi`, which appears to be active on the Thinkpads. ``` dmesg | grep thinkpad [ 19.589434] thinkpad_acpi: ThinkPad ACPI Extras v0.26 [ 19.589439] thinkpad_acpi: http://ibm-acpi.sf.net/ [ 19.589440] thinkpad_acpi: ThinkPad BIOS N22ET50W (1.27 ), EC unknown [ 19.589441] thinkpad_acpi: Lenovo ThinkPad T480s, model 20L7CTO1WW [ 19.591883] thinkpad_acpi: radio switch found; radios are enabled [ 19.591898] thinkpad_acpi: This ThinkPad has standard ACPI backlight brightness control, supported by the ACPI video driver [ 19.591899] thinkpad_acpi: Disabling thinkpad-acpi brightness events by default... [ 19.612278] thinkpad_acpi: rfkill switch tpacpi_wwan_sw: radio is unblocked [ 19.643468] thinkpad_acpi: Standard ACPI backlight interface available, not loading native one [ 19.674512] thinkpad_acpi: battery 1 registered (start 0, stop 100) [ 19.674576] input: ThinkPad Extra Buttons as /devices/platform/thinkpad_acpi/ ``` `thermald` is not loaded. ### General notes: https://www.kernel.org/doc/html/v4.12/admin-guide/pm/intel_pstate.html - This link suggests removing `irqbalance` but I'm skeptical. https://askubuntu.com/questions/1067866/ubuntu-18-04-steam-games-frame-rate-drop/1073353#1073353?newreg=c7c120f373da4effb7317104571cd573 - https://cateee.net/lkddb/web-lkddb/XEN_ACPI_PROCESSOR.html Regarding xen_acpi_processor: "It also registers itself as the SMM so that other drivers (such as ACPI cpufreq scaling driver) will not load." How could `lsmod` report `xen_acpi_processor` as loaded but `xenpm` shows the scaling driver `acpi-cpufreq` ? This might make sense as to the missing `/sys/devices/.../cpufreq` entries. - The following exchange is dubious at best, the final post gets down to the point of disabling intel microcode. They also suggest the use of `msr-tools`, but that really shouldn't be necessary. https://bbs.archlinux.org/viewtopic.php?id=231077 - This is good work, but in my opinion, running a script every few seconds in dom0 isn't a legitimate fix. https://github.com/erpalma/lenovo-throttling-fix --- ### Related issues: https://github.com/QubesOS/qubes-issues/issues/4491 https://github.com/QubesOS/qubes-issues/issues/450