powersave acts like performance governor

English Hardware
1

my laptop is warm, even though there is hardly any cpu usage. Other distros reduce the clock speed in those situations, but cat /proc/cpuinfo always prints 1796.054MHz on suse. I left my freshly restarted pc for 1h - top showed no entry >1%cpu, but still no clock speed reduction.

I would expect my cpu to clock down to 800MHz as long as there is no load. Why doesn’t the powersave-governor do dynamic power saving? Even the wiki says, there is no UI for CPU settings, because there is dynamic powersaving per default: https://en.opensuse.org/Powersaving


% cd /sys/devices/system/cpu/cpu0/cpufreq
% cat affected_cpus 
0
% cat cpuinfo_max_freq 
1800000
% cat cpuinfo_min_freq 
800000
% cat cpuinfo_transition_latency 
4294967295
% cat related_cpus  2 pts/1 /sys/devices/system/cpu/cpu0/cpufreq aenderboy@aeSu
0
% cat scaling_available_governors 
performance powersave
% cat scaling_cur_freq 
1795107
% cat scaling_driver 
intel_pstate
% cat scaling_governor 
powersave
% cat scaling_max_freq 
1800000
% cat scaling_min_freq 
800000
% cat scaling_setspeed 
<unsupported>

CPU: i3-3217U CPU @ 1.80GHz

2

Your CPU supports the intel_pstate driver, which switches “power states” but not necessarily clock frequency. That is, with some loads it is possible that one or more cores go to a “sleep” state without switching frequency before that.
So the frequency you read might be misleading when using intel_pstate. If you really see excessive power drain or much reduced battery operating time there might be a problem though.

3

idle Ubuntu with xfce consumes 13-15 watts
idle suse with xfce consumes 16-17 watts
idle suse without x running consumes 13-14 watts

This really seems neglectable, but i reliably notice a change in temperature of the air exhausted by the fan with my hand. Apparently the cooling of my laptop is optimized for ~14-15W…

EDIT: i guess there’s nothing wrong with the powersaving. It’s just the .5 % more cpu usage of my suse xfce compared to ubuntu xfce that makes the difference.

4

turns out it was the fault of a panel addon for cpu/ram monitoring that prevented my cpu to go into min-powerdrain mode :stuck_out_tongue: