How do you know whether CPU turbo is enabled or disabled? How can I check this?

cat /sys/devices/system/cpu/intel_pstate/no_turbo
echo 1 > /sys/devices/system/cpu/intel_pstate/no_turbo # disable
echo 0 > /sys/devices/system/cpu/intel_pstate/no_turbo # enable

There's a bug in some version of the kernel which causes that file not to report the correct state. This happened because the kernel assumed that the state of the turbo is not changed by the BIOS at runtime. In this case, just look at the max CPU frequency you can get. If you look for more info on your CPU, you'll find the max turbo frequency and max non-turbo frequency.


Additional note on the bug. I'm also able to have the turbo enabled while using the battery because of the bug. I just need to suspend the laptop while plugged, unplug it and then resume it.

Thank you for the commands. That's very interesting for me to know! I hope that the bug is fixed soon.

Is this for sure a BIOS bug? Why are you confident it is the BIOS that is making the change since I guess the kernel or even in user space can ask for the change.

The BIOS and the kernel (and thus userspace) disable the turbo in a different way. The BIOS makes it completely unavailable.

If you try to change the state of the turbo as I wrote in my previous post while unplugged (using a recent kernel release), you get an EPERM error and "Turbo disabled by BIOS or unavailable on processor" in your kernel log.

http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=4521e1a0ce173daa23dfef8312d09051e057ff8e

EDIT: to answer the question, no, I'm not using the Dell factory image.