If the driver requires governor tunables to be per-policy, they are located in a subdirectory of each policy directory. All SuperH processors supporting rate rounding through the clock. This would be best used in a battery powered environment. Since the boosting functionality depends on the load of the whole package, single-thread performance may vary because of it which may lead to unreproducible results sometimes. The difference is that it gracefully increases and decreases the CPU speed rather than jumping to max speed the moment there is any load on the CPU.

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CPU frequency scaling

Now that they are loaded we can configure the governor. This means that either the hardware can be put into states in which it is able to trigger boosting in the hardware-based caseor the software is allowed to trigger boosting in the software-based case. However, that observation may not hold for performance scaling algorithms based on information provided by the hardware itself, for example through feedback registers, as that information is typically specific to the hardware interface it comes from and may not be easily represented cpufgeq an abstract, platform-independent way.

The cpb knob is never present for any processors without the underlying hardware feature e. The only values that can be written to this file are 0 and 1.

CPU Performance Scaling — The Linux Kernel documentation

Therefore there is a natural tradeoff between the CPU capacity the number of instructions that can be executed over a unit amv time and the power drawn by the CPU. If not then use the CPU info you found and figure out which module you need to load. Otherwise, the frequency will not be changed. Consequently, the same set of scaling governors should be suitable for cpufteq supported platform. Page 1 of 5.


In some other cases, however, it may not be necessary to execute instructions so quickly and maintaining the highest cpufreqq CPU capacity for a relatively long time without utilizing it entirely may be regarded as wasteful. Below is a command that will help you identify what type of processor s you have. If not here are the commands to load the modules. Typically, they are used along with algorithms to estimate the required CPU capacity, so as to decide which P-states to put the CPUs into.

Current frequency of the CPU as obtained from. If that is the case check your BIOS’s manual for more information.

HowTo/CpuFrequencyScaling – Debian Wiki

This is the frequency. Performance governor – CPU runs at max frequency regardless of load. Frequency fluctuations in some bursty workloads may be avoided this way at the cost of cpuffreq energy spent on maintaining the maximum CPU capacity.

Boosting means overclocking the processor, although under controlled conditions. The preferred interface is located in the sysfs filesystem.

acpi-cpufreq: Add support for modern AMD CPUs

Some BIOS’s may not have an option for either. Namely, cufreq avoids changing the frequency significantly over short time intervals which may not be suitable for systems with limited power supply capacity e.

When you installed your system there is a very good chance your CPU cpufrrq detected by default and the module you need for for scaling is already running. The purpose of this tunable is to reduce the scheduler context overhead of the governor which might be excessive without it.


Written by Michael Larabel in Software on 21 August When set to ‘0’ its defaultall processes are counted towards the ‘cpu utilization’ value.

You can change this value to anywhere between 0 and where ‘0’ will effectively lock your CPU at a speed regardless of its load whilst ” will, in theory, make it behave identically to the “ondemand” governor. One of the reasons you might want to do smd would be to save energy. CPU frequency ad does what it sounds like. You can go about setting these on reboot a few a,d. The policy objects created during CPU initialization and other data structures associated with them are torn down 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.

This typically can happen through often not. All of the frequency scaling will be done with kernel modules and not user space governors. The following processors for the x86 architecture are supported by cpufreq: