Enable intel p_state Ubuntu 15.04

Question

How to enable Intel_pstate in Ubuntu 15.04?

Solution

In 15.04 it's enabled by default thanks to @solsTiCe informative notes. you could check that yourself

if grep -i pstate /boot/config-$(uname -r) says yes then it's so.

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To enable intel_pstate in Ubuntu 14.04 , edit the /etc/default/grub configuration file with a text editor as root

gksu gedit /etc/default/grub

And for "GRUB_CMDLINE_LINUX_DEFAULT=" , add "intel_pstate=enable", like this:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash intel_pstate=enable"

Save the file and update Grub:

sudo update-grub

Restart your system and to check if intel_pstate is enabled, run the following command:

cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_driver

The command above should return "intel_pstate".

source and more information

Comments

[Pilot6]

There is no need to set boot parameters. It is enabled by default.

[Maythux]

intel_pstate=enable is enabled by default?

[Pilot6]

At least in Ubuntu 3.19 kernel cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_driver gives intel_pstate without any boot parameters.

[Maythux]

cat: /sys/devices/system/cpu/cpu*/cpufreq/scaling_driver: No such file or directory This is my output

[Maythux]

Linux user 3.19.0-15-generic #15-Ubuntu SMP Thu Apr 16 23:32:01 UTC 2015 i686 i686 i686 GNU/Linux

[Pilot6]

3.19.0-18 is current. 15 was pre-release and with a lot of bugs.

[Maythux]

This is the ISO downloaded last day

[solsTiCe]

"Starting with kernel 3.9, the new pstate power scaling driver is used automatically for modern Intel CPUs instead of the other drivers below." Source: Arch wiki

[Maythux]

So what about old kernels? How to enable it?

[solsTiCe]

In Ubuntu: linux (3.16.0-0.2) utopic; urgency=low Revert "SAUCE: intel_pstate -- toggle default to disable"

[solsTiCe]

theoretically, only trusty (14.04) needs this to be enabled like said above (when you use up to date kernel). And you need to enable it because it has been disabled by a ubuntu patch

[PlugaruT]

Thanks for reply, in 14.04 I have enabled it, but in 15.04 I was not sure if should I enable it or it it enabled by default.

[Pilot6]

I have Ubuntu 14.04 and it is enabled by default. It is 3.16.0-38. It is enabled there too. So no need for doing that.

[Pilot6]

@solstice Setting has been reverted. It means now it is default.

[solsTiCe]

yes. But I did not see the revert patch on trusty kernel changelog. that's why I said that. kernel.ubuntu.com/git/ubuntu/ubuntu-trusty.git/log/…