Experiences with CPUFREQ / powersaving

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specs
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Experiences with CPUFREQ / powersaving

Unread post by specs » Sun Dec 01, 2019 8:22 pm

I believe the standard Ubuntu version on the distributed media with the N2 come with the setting:
CPU 0-1 667-1900MHz / governor "intermediate"
CPU 2-5 667-1800MHz / governor "intermediate"

When testing I found a workable solution with
CPU 0-1 250-1900MHz / governor "intermediate"
CPU 2-5 250-1800MHz / governor "intermediate"

When switching to "ondemand" or a lower limit of 100MHz I find the N2 unstable (not response, sometimes requiring a reboot).
While "intermediate" results in a responsive system it might not be the most efficient governor.

Are there other experiences with a powersave setting which does lead to a non-responsive system?
What powersave settings do you recommend?
Is disabling cores really helping in powersaving or is it just limiting the system?

I believe the simple accessories I use to check the power use might not be reliable for a good comparison when running behind a AC-DC convertor. But then again I'm no electrician. After the testing period the system should work from battery power, were the measurement should be easier.

Thanks in advance.

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vjoel
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Re: Experiences with CPUFREQ / powersaving

Unread post by vjoel » Tue Dec 03, 2019 6:21 am

On my N2, "intermediate" is not listed by cpufreq-info:

Code: Select all

  available cpufreq governors: ondemand, powersave, userspace, conservative, interactive, performance, schedutil
I'm using ondemand with 100MHz min and 1.9/1.8 GHz max. I have not noticed a hang/reboot problem, except possibly once during a long-running build using all 6 cores, That has not happened again, but I've only done a few other builds.

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Re: Experiences with CPUFREQ / powersaving

Unread post by odroid » Tue Dec 03, 2019 8:18 am

As far as I remember, the difference of idle power consumption between 100Mhz and 667Mhz was very negligible.
So 667Mhz minimal clock will give you much better responsiveness with slightly higher electric cost.
Also note that, 100Mhz is not sufficient to handle some sudden heavy tasks.
It seems to be mains reason why x86 and other famous ARM boards set the minimal clock at higher than 500Mhz.

BTW, we've used Performance governor only.

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