Re: beaglebone: changing cpu frequency

[Matt Thomas <matt%3am-software.com@localhost>]

On Aug 1, 2013, at 3:37 PM, John Klos <john%ziaspace.com@localhost> wrote:

>> I finally debugged the code I added to allow the changing of the
>> CPU frequency on the beaglebone (regardless of color).
>> 
>> Use sysctl to change it:
>> 
>> # sysctl -w machdep.frequency.current=1000
>> cpu0: frequency changed from 550 MHz to 1000 MHz
>> machdep.frequency.current: 550 -> 1000
> 
> It works, sorta. All frequencies work except 1 GHz:
> 
> cpu0: frequency changed from 550 MHz to 600 MHz
> cpu0: frequency changed from 600 MHz to 650 MHz
> cpu0: frequency changed from 650 MHz to 700 MHz
> cpu0: frequency changed from 700 MHz to 720 MHz
> cpu0: frequency changed from 720 MHz to 800 MHz
> cpu0: frequency changed from 800 MHz to 900 MHz
> 
> When trying 1000 MHz, the BeagleBone Black locks up and isn't responsive 
> either on the network or via serial.

What power source?  I have a 4A (2500ma) 5V supply.

> On the other hand, the speed is actually being changed:
> 
> 550 MHz, time ./primes
> 1000000, 15485863
>      183.96 real       183.54 user         0.02 sys
> 
> 900 MHz, time ./primes
> 1000000, 15485863
>      112.29 real       112.11 user         0.01 sys

I've been running with 1000 with no problems.