Is this a bug with cpu scaling and the tuned service tuned-ppd

Ask Fedora
1

I’m using F43 with the new 6.18 kernel on an amd Ryzen 16x Ryzen 7 5800X 8-Core Processor. I’ve been using Fedora KDE for just under a month and love it.

Playing around, i see that in the panel there is an applet for power, I can set power profiles to balanced, powersave or performance. I believe this uses the new tuned daemon which is active:

   1490 ?        00:00:01 tuned
   1593 ?        00:00:00 tuned-ppd

The sudo systemctl status tuned command confirms it’s active. I’ve left the slide on balanced since the install. This is confirmed with:

$ tuned-adm active
Current active profile: balanced

Yet…looking in this directory:

harry1@landlord:/sys/devices/system/cpu/cpu5/cpufreq

-r–r–r–. 1 root root 4096 Jan 8 18:00 affected_cpus
-r–r–r–. 1 root root 4096 Jan 8 18:00 amd_pstate_highest_perf
-r–r–r–. 1 root root 4096 Jan 8 18:00 amd_pstate_hw_prefcore
-r–r–r–. 1 root root 4096 Jan 8 18:00 amd_pstate_lowest_nonlinear_freq
-r–r–r–. 1 root root 4096 Jan 8 18:00 amd_pstate_max_freq
-r–r–r–. 1 root root 4096 Jan 8 18:00 amd_pstate_prefcore_ranking
-rw-r–r–. 1 root root 4096 Jan 8 17:40 boost
-r–r–r–. 1 root root 4096 Jan 8 18:00 cpuinfo_avg_freq
-r–r–r–. 1 root root 4096 Jan 8 12:55 cpuinfo_max_freq
-r–r–r–. 1 root root 4096 Jan 8 12:55 cpuinfo_min_freq
-r–r–r–. 1 root root 4096 Jan 8 18:00 cpuinfo_transition_latency
-r–r–r–. 1 root root 4096 Jan 8 12:55 energy_performance_available_preferences
-rw-r–r–. 1 root root 4096 Jan 8 17:46 energy_performance_preference
-r–r–r–. 1 root root 4096 Jan 8 18:00 related_cpus
-r–r–r–. 1 root root 4096 Jan 8 12:55 scaling_available_governors
-r–r–r–. 1 root root 4096 Jan 8 12:55 scaling_cur_freq
-r–r–r–. 1 root root 4096 Jan 8 18:00 scaling_driver
-rw-r–r–. 1 root root 4096 Jan 8 17:46 scaling_governor
-rw-r–r–. 1 root root 4096 Jan 8 18:00 scaling_max_freq
-rw-r–r–. 1 root root 4096 Jan 8 18:00 scaling_min_freq
-rw-r–r–. 1 root root 4096 Jan 8 18:00 scaling_setspeed

and executing the command: cat scaling_governor

I see “powersave”

Hand in hand with that, the contents of these files confirms the "powersave" state.

harry1@landlord:/sys/devices/system/cpu/cpu5/cpufreq$ cat scaling_min_freq 
1754308
harry1@landlord:/sys/devices/system/cpu/cpu5/cpufreq$ cat scaling_max_freq 
4853585
harry1@landlord:/sys/devices/system/cpu/cpu5/cpufreq$ cat scaling_cur_freq 
1754308

So which is correct, and why are they different?

2

I am not sure how you relate that to tuned-ppd,
But the scaling_min_freq is the minimum freq the cpu is capable of running (1.75 GHz).
Similarly the scaling_max_freq is the maximum freq the cpu can operate (4.8 GHz).
The scaling_cur_freq is the current operating freq for the cpu (presently minimum)

3

I am a non-techincal person. I am not “computersavvy” so forgive me. The scaling_cur_freq is telling me I’m running at the slowest speed, and the tuned-ppd is telling me I’m somewhere in between high and low (balanced). If you think that’s normal, it’s fine with me. I’m just pointing out what I see in case it can be useful.

4

The balanced setting is a moderate scaling of speeds. Each setting allows the cpu to idle at the lowest setting until it needs higher speeds for the current task. Thus those seen normal and nothing to be concerned about. Powersave settings scale the cpu speeds at a slower rate and performance settings tend to ramp up the speeds quicker. Balanced is in between in how quickly the speeds are scaled up.

If you noted that you were running something that made the computer seem bogged down and the current speed was still at minimum there may be cause for concern but with the snapshot you provided I would not be concerned.

Also note that the scaling governor may not display settings the same as tuned since you are looking at the lowest level with the settings seen in that directory, and tuned is designed to adjust the settings as needed as it ‘tunes’ the performance based on demand. Tuned makes adjustments moment by moment.

5

Got it. Thank you