<Closed> TLP - ON/Off-line Settings for CPU Cores

makh · 2015-09-07 09:48:55

I intend to add the following in /etc/default/tlp using the parameter run-on-bat for all the cores/threads except the first one:

for i in /sys/devices/system/cpu/cpu*/online; do echo 0 > $i; done

and using the parameter run-on-ac:

for i in /sys/devices/system/cpu/cpu*/online; do echo 1 > $i; done

But tlp isnt accepting these command arguments:

run_on_bat for i in /sys/devices/system/cpu/cpu*/online; do echo 0 > $i; done
RUN_ON_BAT for i in /sys/devices/system/cpu/cpu*/online; do echo 0 > $i; done
run-on-bat for i in /sys/devices/system/cpu/cpu*/online; do echo 0 > $i; done

Kindly advise.
Thanks in advance.

Last edited by makh (2017-01-28 04:13:32)

linrunner · 2015-09-07 21:50:39

Hi,

what you're trying does not work for two reasons:

1. There is no parameter RUN_ON_BAT in the TLP config file. There is just the command line tool run-on-bat which is not executed automatically upon change of power source. TLP intentionally has no feature to execute user defined commands automatically.

2. run-on-bat works only with command executables but "for ..." is a shell construct that must be interpreted by a shell. You have to use something like run-on-bat sh -c "for ..." or put your commands in a script. But this won't achieve what you want because of 1.

Apart from the above obstacles i seriously doubt that statically turning off cores like this will save battery power at all. This is the reason TLP doesn't have such a feature.

Did you conduct measurements yourself?

EDIT: 3. /sys/devices/system/cpu/cpu*/online is not present in current kernels (3.19 w/ acpi-cpufreq and 4.2 w/ intel_pstate)

Last edited by linrunner (2015-09-11 16:06:43)

makh · 2015-09-09 09:30:38

Thanks for your reply.

I didnt made any measurements, just saw in blogs that people turn off extra cores, so wanted to do it, thinking it may benefit.

Regarding the arch system file:

$ for r in [0123]; do echo /sys/devices/system/cpu/cpu*/online ;done
/sys/devices/system/cpu/cpu1/online /sys/devices/system/cpu/cpu2/online /sys/devices/system/cpu/cpu3/online

$ uname -r
4.1.6-1-ARCH

linrunner · 2015-09-11 16:09:46

makh wrote:

just saw in blogs that people turn off extra cores, so wanted to do it, thinking it may benefit.

Better to measure yourself ... :-)

makh wrote:

/sys/devices/system/cpu/cpu1/online /sys/devices/system/cpu/cpu2/online /sys/devices/system/cpu/cpu3/online

You're right, i made the mistake to look in cpu0 :-(.

Arch Linux

#1 2015-09-07 09:48:55

<Closed> TLP - ON/Off-line Settings for CPU Cores

#2 2015-09-07 21:50:39

Re: <Closed> TLP - ON/Off-line Settings for CPU Cores

#3 2015-09-09 09:30:38

Re: <Closed> TLP - ON/Off-line Settings for CPU Cores

#4 2015-09-11 16:09:46

Re: <Closed> TLP - ON/Off-line Settings for CPU Cores

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