Disabling Laptop-mode-tools doesn't disable CPU Frequency scaling?

dejy · 2015-01-13 15:41:45

I'm rather unclear on this - good someone explain the logic behind this? Since enabling laptop-mode-tools enables the frequency scaling shouldn't disabling it cancel? Why do I need to use a separate utility for this?

Lone_Wolf · 2015-01-13 16:00:00

LMT doesn't enable cpu frequency scaling but a special laptop mode .

archlinux wiki wrote:

CPU frequency scaling is implemented in Linux kernel, the infrastructure is called cpufreq. Since kernel 3.4 the necessary modules are loaded automatically and the recommended ondemand governor is enabled by default.

The quote above is from the archwiki CPU frequency scaling page, check it for more details.

dejy · 2015-01-13 16:48:58

From laptop-mode.conf

# Enable all simple zero-configuration auto modules
# This option enables all simple modules (listed below) without requiring
# the user to enable each module individually
#
# List of modules which can be automatically enabled with this setting are:
#
# ac97-powersave
# cpufreq
# dpms-standby
# eee-superhe
# ethernet
# exec-commands
# hal-polling
# hdparm
# intel-hda-powersave
# intel-sata-powermgmt
# nmi-watchdog
# pcie-aspm
# runtime-pm
# sched-mc-power-savings
# sched-smt-power-savings
# terminal-blanking
# usb-autosuspend
# wireless-ipw-power
# wireless-iwl-power
# wireless-power
#
# Set this to 1 to enable all simple zero-configuration auto modules listed above.
#
# NOTE: You can explicitly enable/disable any of the above modules by changing their
# values in the individual settings file
#
ENABLE_AUTO_MODULES=1

Laptop-mode is loading these modules, my point is I don't understand why disabling laptop-mode doesn't unload or set to default the changes laptop-mode effected when it was enabled - I shouldn't have to go track down the changes in each individual module after disabling laptop mode or be forced to reboot.

Last edited by dejy (2015-01-13 16:50:12)

lucke · 2015-01-13 16:54:18

The kernel loads acpi-cpufreq and whatnot automatically, I believe, so if you don't want them, you should blacklist them.

dejy · 2015-01-13 16:58:02

lucke wrote:

The kernel loads acpi-cpufreq and whatnot automatically, I believe, so if you don't want them, you should blacklist them.

I do want them - but when I need to run computations and I'm not plugged in it should be simple to reverse. Laptopmode includes a `cpufreq.conf` which alters the governor and performance settings based on the config values.

lucke · 2015-01-13 17:10:49

You boot your system, without LMT running, you have frequency scaling with the ondemand governor. You start LMT, it perhaps modifies cpufreq settings (by default it uses ondemand on AC, it seems, thus nothing changes if you are running on AC with default settings). Why should disabling LMT turn off frequency scaling? Maybe disabling it should make it go to the default governor, maybe it even does, I don't know.

You can use LMT to have a different governor on battery and AC. I don't know what exactly you want.

quequotion · 2015-01-13 17:56:24

dejy wrote:

when I need to run computations and I'm not plugged in it should be simple to reverse

This is exactly the problem indicator-powersave solves.

Arch Linux

#1 2015-01-13 15:41:45

Disabling Laptop-mode-tools doesn't disable CPU Frequency scaling?

#2 2015-01-13 16:00:00

Re: Disabling Laptop-mode-tools doesn't disable CPU Frequency scaling?

#3 2015-01-13 16:48:58

Re: Disabling Laptop-mode-tools doesn't disable CPU Frequency scaling?

#4 2015-01-13 16:54:18

Re: Disabling Laptop-mode-tools doesn't disable CPU Frequency scaling?

#5 2015-01-13 16:58:02

Re: Disabling Laptop-mode-tools doesn't disable CPU Frequency scaling?

#6 2015-01-13 17:10:49

Re: Disabling Laptop-mode-tools doesn't disable CPU Frequency scaling?

#7 2015-01-13 17:56:24

Re: Disabling Laptop-mode-tools doesn't disable CPU Frequency scaling?

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