jackb_guppy
Posts: 5
Joined: Tue Nov 05, 2019 1:37 am

RPi4B throttling > 40C

Tue Nov 05, 2019 2:17 am

I been testing my new desktop cooling and other things. I have releasing my RPI4B 3D printed box design shortly.

Before last apt-get on Friday Nov 1. I could run my 4B at 100% trans-coding video from 480p to 720p or back at a rate of 1x frame rate. After the update is now only works at 0.3x frame rate. (3 times slower). What I have before and after is temperature measurements of 42C at idle, to 72C at max load (trans-coding). Now I get is 39C idle and 47C at max load.

I was reading the temp once per sec with: vcgencmd measure_temp | tr -dc [:digit:]

I turned on "CPU Temperature Monitor" in the tool bar. It is displaying the same information. But is also shoing throttling cpu when the temperature goes over 40C.

Running: "vcgencmd measure_clock arm" when it shows throttled shows: frequency(48)=600117184
When my browser is closed and full at idle is shows like frequency(48)=1500000000

the clock is dropping to about 1/3 max rate.

The only change besides the update was correcting my video to be: hdmi_group=2 & hdmi_mode=58 - fixing a black screen issue during boot. My first testing was using a desktop tv 1080p, the boot just worked.

Any ideas how to correct?

jdb
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 2161
Joined: Thu Jul 11, 2013 2:37 pm

Re: RPi4B throttling > 40C

Tue Nov 05, 2019 10:48 am

Your CPU isn't being thermally throttled. The clock speed is being reduced due to the ondemand cpufreq governor.
https://www.kernel.org/doc/Documentatio ... ernors.txt
Rockets are loud.
https://astro-pi.org

jackb_guppy
Posts: 5
Joined: Tue Nov 05, 2019 1:37 am

Re: RPi4B throttling > 40C

Tue Nov 05, 2019 5:20 pm

Thank you for your answer. But I do not see in the link anything to help me correct the issue.

Do I need to make a change in config.txt? I see in there a frequency setting of 600.
Is there another config to change?
Was there a change initialization of cpu, that I need to roll-back or reload?

Last why is the "CPU Temperature Monitor showing throttling is present, when you say it is not?

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PeterO
Posts: 5156
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Re: RPi4B throttling > 40C

Tue Nov 05, 2019 5:40 pm

jackb_guppy wrote:
Tue Nov 05, 2019 5:20 pm
Thank you for your answer. But I do not see in the link anything to help me correct the issue.
It's not an issue. It's supposed to do that !
The "on demand" part means that when the CPU load is small the clock speed is reduced to save power and keep the CPU cooler.
When the "demand" increases the clock speed is increased to handle it.

PeterO
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jackb_guppy
Posts: 5
Joined: Tue Nov 05, 2019 1:37 am

Re: RPi4B throttling > 40C

Tue Nov 05, 2019 11:11 pm

I am sorry to be so thick headed,

IT does not shift out that mode. Even at load average of over 20 and all 4 CPU at 100% is still in 1st gear!

vcgencmd measure_clock arm
frequency(48)=600117184

Running both ffmpeg and stress to force the load.

I have tested before the last update at are this load CPU temp got to 80C without cooling. Now it is not even reaching 65C, Something is keeping the temperature down. It is not cooling (unplugged) so what else is there?

Again, "CPU TEMPERATURE MONITOR is showing that throttling is ON.

In all fairness you may be right, but it keeps looking wrong to me.

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Imperf3kt
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Location: Australia

Re: RPi4B throttling > 40C

Wed Nov 06, 2019 6:02 am

Do you have a lightning bolt in the top right corner of the screen?
The Pi will also throttle when receiving insufficient power and the lightning icon (and a blinking red LED) is the first indicator.
55:55:44:44:4C
52:4C:52:42:41

renice123
Posts: 102
Joined: Tue Oct 15, 2019 3:56 pm

Re: RPi4B throttling > 40C

Wed Nov 06, 2019 7:30 am

There was a old problem with Debian (arm) and cpufreq. In general terms, it can be described as the inability to work correctly with the kernel and display the correct information. Programs working with the “hardware” are always specific and prone to errors, this is understandable - computer hardware is different. It is reported that now the kernel works with cpufreq, the problem was somehow solved, but I believe that the program still has “bugs” (or hallucinations).
The accompanying package program also remained without support https://bugs.debian.org/cgi-bin/bugrepo ... bug=933159
Try to see the information cpufreq-info - my output tells me the following.

hardware limits: 300 MHz - 1.50 GHz
available frequency steps: 300 MHz, 1.50 GHz
current CPU frequency is 300 MHz.
cpufreq stats: 300 MHz:23.50%, 1.50 GHz:76.50% (10828)


As you can see, Raspberry works mainly at a frequency of 1.50 GHz (76.50% of the time), but
current CPU indicates a frequency of 300 MHz (frequency at this moment).

PS I changed config.txt to a minimum frequency of 300 MHz to see if there will be a decrease in current consumption and a decrease in temperature.

jackb_guppy
Posts: 5
Joined: Tue Nov 05, 2019 1:37 am

Re: RPi4B throttling > 40C

Thu Nov 07, 2019 7:42 pm

renice123

Thank you the information. added cpufrequtils to get the cpufreq-info.

found that "stress -c 4" does peg 100% utilize, but does not give CPU full workout. The 600Mhz/1.5GHz is spilt to 55%/45%. running ffmpeg the split is more 15%/85%. With cooling in place I am maxing temperature at 48C using ffmpeg. Idle is 38C.

Would like to see "CPU Temperature Monitor" throttling fixed. Under max load with ffmpeg I am getting throttling showing with with normal showing once per min. This keeps making think that throttle is still present.

trejan
Posts: 924
Joined: Tue Jul 02, 2019 2:28 pm

Re: RPi4B throttling > 40C

Thu Nov 07, 2019 8:03 pm

What does "sudo vcgencmd get_throttled" say when it is idle and when you've got ffmpeg or stress running?

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