Control CPU frequency on Raspberry Pi with FreeBSD 10.2

FreeBSD 10.2-RELEASE became available at 13 August 2015.
One of the added features is the bcm2835_cpufreq driver, which supports CPU frequency and voltage control on the Raspberry Pi.

Let’s check how it works.

First, we will load new image and check new driver in the systems messages.


We see the bcm2835_cpufreq0 device.

Next, we will check the kernel’s value for control CPU.


User-level interface for changing CPU frequency is the cpufreq(4) driver.

Let’s check that this driver is loaded.


It’s time now to try it.


It’s work.

Control CPU frequency automatically

We can change CPU frequency automatically using powerd(8) utility.
The powerd(8) utility monitors the system state and sets various power control options accordingly.


Option “-a hadp” turn on hiadaptive mode. This mode attempts to strike a balance by degrading performance when the system appears idle and increasing it when the system is busy, but tuned for systems where performance and interactivity are more important than power consumption.

To turn on this control permanently we should add options for powerd(8) to the /etc/rc.conf(5)


After reboot we can check it.


That’s all folks!


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