[fedora-arm] BeagleBone Black CPU speed

[Robert Nelson]

On Tue, Jan 21, 2014 at 10:09 PM, Steve Underwood <steveu at coppice.org> wrote:
> Hi Peter,
>
>
> On 01/22/2014 04:14 AM, Peter Robinson wrote:
>>>>
>>>> It looks like the BeagleBone Black is still running at 550MHz with the
>>>> latest Fedora 20. Does anyone know what is holding it back from running
>>>> at
>>>> 1GHz? Is the a uboot thing, or a kernel thing, or something else? I saw
>>>> a
>>>> version of uboot referred to as making the BBB run at 1GHz, but when I
>>>> tried
>>>> experimenting with that I got the same 550MHz clock speed.
>>>
>>> If you're interested could you try the kernel-3.13.0-1.1.fc20 scratch
>>> kernel [1] on your BBBlack. It should add freq scaling support and you
>>> should be able to tell if it detects it appropriately if the
>>> cpufreq-cpu0 module loads. Feedback welcome.
>>
>> So that kernel works with my testing but the module doesn't auto load
>> the cpufreq-cpu0 module. If you do:
>>
>> modprobe cpufreq-cpu0
>>
>> You then get:
>> cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies
>> 300000 600000 800000 1000000
>>
>> Even with 3.12.8 you can manually load that module and it works but
>> you only get up to 720mhz.
>>
>> Peter
>>
>>> [1]
>>> http://pbrobinson.fedorapeople.org/arm-kernel/kernel-3.13.0-1.1.fc20.armv7hl.rpm
>
> Earlier Jos Vos reported the following results for his BeagleBoneBlack
> running pystone.py
>
> Fedora:
> Pystone(1.1) time for 50000 passes = 10.9073
> This machine benchmarks at 4584.1 pystones/second

Which governor are you using?  It seems to be definitely stuck at 300Mhz

3.13.0-bone4 (what i'm shipping to debian bone users..)

# cpufreq-set --freq 300000
# /usr/lib/python2.7/test/pystone.py
Pystone(1.1) time for 50000 passes = 11.37
This machine benchmarks at 4397.54 pystones/second

# cpufreq-set --freq 600000
# /usr/lib/python2.7/test/pystone.py
Pystone(1.1) time for 50000 passes = 5.67
This machine benchmarks at 8818.34 pystones/second

# cpufreq-set --freq 800000
# /usr/lib/python2.7/test/pystone.py
Pystone(1.1) time for 50000 passes = 4.28
This machine benchmarks at 11682.2 pystones/second

# cpufreq-set --freq 1000000
# /usr/lib/python2.7/test/pystone.py
Pystone(1.1) time for 50000 passes = 3.35
This machine benchmarks at 14925.4 pystones/second

When just leaving the ondemand govenor set:

cpufrequtils 008: cpufreq-info (C) Dominik Brodowski 2004-2009
Report errors and bugs to cpufreq at 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 "ondemand" may decide which speed to use
                  within this range.
  current CPU frequency is 1000 MHz (asserted by call to hardware).
  cpufreq stats: 300 MHz:0.00%, 600 MHz:0.00%, 800 MHz:0.00%, 1000 MHz:100.00%

# /usr/lib/python2.7/test/pystone.py
Pystone(1.1) time for 50000 passes = 3.39
This machine benchmarks at 14749.3 pystones/second

Regards,

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