Setting the CPU speed.

[cwrse...@gmail.com]

I've been looking at the speed of my BBB and not really understanding
what's going on.  The files under /sys/devices/system/cpu/cpu0/cpufreq
show that the performance governor is in use, but the speed is a constant
550,000 whatever the load.  The "scaling_setspeed <unsupported>" entry
probably reflects this; does anyone know how I set up a kernel to handle
the BBB's CPU speed control?

(This is on debian, btw)

Thanks - Will

tuppence ~ # cpuspeed.sh
affected_cpus 0
cpuinfo_cur_freq 550000
cpuinfo_max_freq 1000000
cpuinfo_min_freq 300000
cpuinfo_transition_latency 300000
related_cpus 0
scaling_available_frequencies 300000 600000 800000 1000000
scaling_available_governors conservative ondemand userspace powersave performance
scaling_cur_freq 550000
scaling_driver generic_cpu0
scaling_governor performance
scaling_max_freq 1000000
scaling_min_freq 300000
scaling_setspeed <unsupported>
tuppence ~ #

[Maxim Podbereznyy]

cpufreq-info
cpufreq-set

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[William Hermans]

Honestly unless you have a specific reason I think the default ( ondemand ) governor is probably the best. While idle for me the CPU has always been 300Mhz, and with a heavy load ( over 60% load ) the CPU goes up to 1Ghz.

 

[Carl-Fredrik Sundström]

I would like to test my application at different lower CPU Frequencies to make sure that it would work on a custom board with a lower specced sitara processor. Could I lock the CPU at max 600 or 720 MHz ?

[William Hermans]

Yeah experiemnt with the different govenors. also type cpufreq-set /? for help or man cpufreq-set

[Robert Nelson]

On Fri, Mar 14, 2014 at 4:46 PM, Carl-Fredrik Sundström
<audi...@gmail.com> wrote:
>
> I would like to test my application at different lower CPU Frequencies to
> make sure that it would work on a custom board with a lower specced sitara
> processor. Could I lock the CPU at max 600 or 720 MHz ?

voodoo@am335x-boneblack-512mb-1:~$ sudo cpufreq-set -f 800000

voodoo@am335x-boneblack-512mb-1:~$ cpufreq-info
cpufrequtils 008: cpufreq-info (C) Dominik Brodowski 2004-2009
Report errors and bugs to cpu...@vger.kernel.org, please.
analyzing CPU 0:
driver: generic_cpu0
CPUs which run at the same hardware frequency: 0
CPUs which need to have their frequency coordinated by software: 0
maximum transition latency: 300 us.
hardware limits: 300 MHz - 1000 MHz
available frequency steps: 300 MHz, 600 MHz, 800 MHz, 1000 MHz
available cpufreq governors: conservative, ondemand, userspace,
powersave, performance
current policy: frequency should be within 300 MHz and 1000 MHz.
The governor "userspace" may decide which speed to use
within this range.
current CPU frequency is 800 MHz. <= BINGO
cpufreq stats: 300 MHz:3.87%, 600 MHz:0.01%, 800 MHz:0.01%, 1000
MHz:96.11% (30)


just use cpufreq-set -f (freq)

Regards,

--
Robert Nelson
http://www.rcn-ee.com/

[cwrse...@gmail.com]

Sorry, I should have said that I'd tried cpuinfo. I can change the
governor (with -g), but not the frequency:

tuppence ~ # cpufreq-set -f 1000MHz
tuppence ~ # cpufreq-info

cpufrequtils 008: cpufreq-info (C) Dominik Brodowski 2004-2009
Report errors and bugs to cpu...@vger.kernel.org, please.
analyzing CPU 0:
  driver: generic_cpu0
  CPUs which run at the same hardware frequency: 0
  CPUs which need to have their frequency coordinated by software: 0
  maximum transition latency: 300 us.
  hardware limits: 300 MHz - 1000 MHz
  available frequency steps: 300 MHz, 600 MHz, 800 MHz, 1000 MHz
  available cpufreq governors: conservative, ondemand, userspace, powersave, performance
  current policy: frequency should be within 300 MHz and 1000 MHz.
                  The governor "userspace" may decide which speed to use
                  within this range.

  current CPU frequency is 550 MHz (asserted by call to hardware).
  cpufreq stats: 300 MHz:nan%, 600 MHz:nan%, 800 MHz:nan%, 1000 MHz:nan%
tuppence ~ #

Whatever happens, the frequency stays at 550 MHz.

All ideas welcome - Will

[Charles Steinkuehler]

On 3/16/2014 9:59 AM, cwrse...@gmail.com wrote:
> Whatever happens, the frequency stays at 550 MHz.
>
> All ideas welcome - Will

Are you running from the DC power jack?

The board is limited to 550 MHz if you use USB power to avoid drawing
more current than USB can provide.

--
Charles Steinkuehler
cha...@steinkuehler.net

[Gerald Coley]

Only the BeagleBone is limited to 550MHZ on USB. Our standard BBB image runs at 1GHz on USB.

Gerald

[Ruben Kertesz]

Could altering the frequency be considered a power saving feature?

[cwrse...@gmail.com]

On Monday, March 17, 2014 3:28:57 PM UTC, Charles Steinkuehler wrote:

On 3/16/2014 9:59 AM, cwrse...@gmail.com wrote:
> Whatever happens, the frequency stays at 550 MHz.
>
> All ideas welcome - Will

Are you running from the DC power jack?

The board is limited to 550 MHz if you use USB power to avoid drawing
more current than USB can provide.

No, I'm running off the DC power jack.  Suspicious, though, that the BBB is using 550 MHz which doesn't seem to be one of the standard speed steps.  I've wondered about that.

Will

 

[Robert Nelson]

>
> No, I'm running off the DC power jack. Suspicious, though, that the BBB is
> using 550 MHz which doesn't seem to be one of the standard speed steps.
> I've wondered about that.

Sounds like a misconfigured kernel.. uname -r would help