Some BIOS’s may not have an option for either. This keeps it up until the process is complete for all cores. Below is a list the governors and how each works. Supported Architectures and Processors. For this reason, CPUFreq allows scaling drivers to bypass the governor layer and implement their own performance scaling algorithms. So when the CPU scales it will only go to a max of and not

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The cpufreq module lists stats about your CPU.

CPU frequency scaling

Page 1 of 5. If you did not find it with lsmod when you first looked then it did not load automatically. You can switch to root and run the same commands just without the sudo sh -c ” ” if you like. Scaling drivers talk to the hardware. Kernel version Make sure your kernel version is at least 2.

This has been merged into the acpi-cpufreq module in later kernels. That is, for example, the same register or set of registers is used to control the P-state of multiple CPUs at the same time and writing to it affects all of those CPUs simultaneously. The time it takes to switch the CPUs belonging to this policy from one P-state to another, in nanoseconds.

This would be good for systems that do a lot of work high load for a short periods of time and then don’t do much low load the rest of the time. Current frequency of the CPU as obtained from. Make sure to not.


We will be scaling the CPU with the kernel so we don’t need these. You can decide which one you fits your needs best.

acpi-cpufreq: Add support for modern AMD CPUs

As a reminder, my launch-day Threadripper WX tests were done using the performance governor across all tested CPUs. By “echoing” a new frequency into this. After you know this then you will know what kernel module you will need to load for it.

Remove any userspace CPU scaling programs There are some userspace programs that can be run to scale the processors frequency. This attribute is not present if the scaling driver in use does not support ajd.

HowTo/CpuFrequencyScaling – Debian Wiki

Boosting means overclocking the processor, although under controlled conditions. To do this the CPU must have the capability to switch the frequency very quickly. If this governor is attached to a policy shared by multiple CPUs, the load is estimated for all of them and the greatest result is taken as the load estimate for the entire policy. Legal Disclaimer, Privacy Policy Contact.

It returns the last frequency requested by the governor in kHz or can be written to in order to set a new frequency for the policy. First of all, a scaling driver a,d to be registered for CPUFreq to work. Performance governor – CPU runs at max frequency regardless of load. Clock scaling allows you to change the clock speed of the CPUs on the. Different names are used by different vendors to refer to this functionality. You can go about setting these on reboot a few ways.


This does not cover thermal ACPI limitations. The policy objects created during CPU initialization and other data structures associated with them are torn cpuffeq when the scaling driver is unregistered which happens when the kernel module containing it is unloaded, for example or when the last CPU belonging to the given policy in unregistered.

The AMD powernow-k8 scaling driver supports a sysfs knob very similar to the global boost one. Then run the command to load it.

Documentation/cpu-freq/ – kernel/common – Git at Google

To show the available governors you can use. The only values that can be written to this file are 0 and 1. I’ve seen discussion on getting rid of this in later kernels don’t count on it being there in the future. National Semiconductors Geode GX.