CPU frequency doesn't move on RPi3 B+

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CPU frequency doesn't move on RPi3 B+

Postby graysky » Mon Mar 19, 2018 11:46 pm

Anyone else experiencing this? Advertises the ondemand governor but reported CPU freq never moves off 1400 MHz. Armv7h.

Script called temps:
$this->bbcode_second_pass_code('', '
#!/bin/bash
freq=$(cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq)
gov=$(cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor)
temp=$(cat /sys/devices/virtual/thermal/thermal_zone0/temp)

echo "CPU temp : $(( temp / 1000 ))°C"
echo "CPU freq : $(bc <<< "scale=0; $freq/1000") MHz ($gov)"')

$this->bbcode_second_pass_code('', '% watch temps
Every 2.0s: temps pi3: Mon Mar 19 19:46:21 2018

CPU temp : 34°C
CPU freq : 1400 MHz (ondemand)
On-line CPU(s) list: 0-3
')
graysky
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Location: /run/user/1000

Re: CPU frequency doesn't move on RPi3 B+

Postby nickerejv » Tue Mar 20, 2018 6:04 pm

Works fine here.

$this->bbcode_second_pass_code('', ' ./temps.sh
CPU temp : 47°C
CPU freq : 600 MHz (ondemand)
# ./temps.sh
CPU temp : 47°C
CPU freq : 1400 MHz (ondemand)
# ./temps.sh
CPU temp : 47°C
CPU freq : 600 MHz (ondemand)')
nickerejv
 
Posts: 5
Joined: Sun Mar 18, 2018 11:57 am

Re: CPU frequency doesn't move on RPi3 B+

Postby graysky » Tue Mar 20, 2018 7:31 pm

If I used the powersave gov, mine does throttle down to 600. Are you on armv7h? Any special management software running?
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Joined: Sun Jun 26, 2011 6:56 am
Location: /run/user/1000

Re: CPU frequency doesn't move on RPi3 B+

Postby jaab » Wed Mar 21, 2018 8:37 am

Hi, it also works fine here on an armv7h plain installation.

[img][alarm@alarmpi Documentos]$ ./temps.sh
CPU temp : 32°C
CPU freq : 600 MHz (ondemand)
[alarm@alarmpi Documentos]$ ./temps.sh
CPU temp : 33°C
CPU freq : 1400 MHz (ondemand)
[alarm@alarmpi Documentos]$ ./temps.sh
CPU temp : 32°C
CPU freq : 1400 MHz (ondemand)
[alarm@alarmpi Documentos]$ ./temps.sh
CPU temp : 32°C
CPU freq : 1400 MHz (ondemand)
[alarm@alarmpi Documentos]$ ./temps.sh
CPU temp : 32°C
CPU freq : 600 MHz (ondemand)
[/img]
jaab
 
Posts: 26
Joined: Sat Oct 22, 2016 8:32 am

Re: CPU frequency doesn't move on RPi3 B+

Postby graysky » Sat Mar 24, 2018 7:02 pm

Just for a comparison, I put raspbian stretch minimal on a spare SD card. Although it uses an older kernel, the governor behaves as expected so something must be up with Arch ARM.

$this->bbcode_second_pass_code('', '$ ~/bin/temps
CPU temp : 33°C
CPU freq : 600 MHz (ondemand)
On-line CPU(s) list: 0-3
')

EDIT: I build 4.9.80 (commit be97febf4aa42b1d019ad24e7948739da8557f66) and found that the problem for me seem to be related to the 4.14.x kernel. On 4.9.80, the ondemand governor gives the expected behavior:
$this->bbcode_second_pass_code('', '
% temps
CPU temp : 47°C
CPU freq : 600 MHz (ondemand)
On-line CPU(s) list: 0-3
')

Even on repeat measurement. Too many variables changed between 4.14.29 and 4.9.80 but that much is clear.

EDIT: https://github.com/raspberrypi/linux/issues/2466
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