Idea #5227: Dynamically disable/enable CPU cores

-23

Written by Eldmannen the 20 Mar 08 at 18:32. Category: System.
Related to: Nothing/Others. Status: New

Description

I have a dual-core CPU. Some people have quad-core CPU. In some months Intel releases a new six-core CPU. Later there will be 8-core CPU and even more...

It would be nice Ubuntu could dynamically disable inactive CPU cores. Example, when the screensaver is running, it could use only 1 core instead of 2, 4, 6 or 8 cores.

This would use less power, make less heat, less noise. Be more economical and ecological.

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zooounds wrote on the 20 Mar 08 at 18:41

Is it even possible? Anyway, I think that an idle core doesn't use much energy at all.

You could use frequency scaling. Works nicely.

Eldmannen wrote on the 20 Mar 08 at 20:21

I do use frequency scaling.

model name : Intel(R) Core(TM)2 CPU 6420 @ 2.13GHz
cpu MHz : 1603.000

Eldmannen wrote on the 21 Mar 08 at 02:10

http://www.mjmwired.net/kernel/Documentation/cpu-hotplug.txt

all you have to do is: enable "CPU Hotplug" in your Linux kernel config and set:

echo 0 > /sys/devices/system/cpu/cpuX/online
and it's in the deepest sleep... (check it out!)

or :
echo 1 > /sys/devices/system/cpu/cpuX/online
to get the CPU up again...

mbappe wrote on the 8 Apr 08 at 01:19

It would be really cool if one could explicitly control the exact set of cores that are enabled.

If not totally dynamically, then is it possible to control the set of cores which are brought online at boot time?

steve196 wrote on the 14 Apr 08 at 14:38

That is a good idea. Even those who buy the fat machines don't need power all the time. On the other hand it might work better to use the cpus own power saving methods.

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