Intel CPU Frequency Governors

After updating the office desktop to Slackware 15.0, an annoying issue was configuring the office desktop CPU frequency governor. The issue was first noticed several years ago and then again with the initial testing of 15.0. The problem affected testing KDE as a desktop environment.

Being now committed to using 15.0 on a daily basis meant dealing with this nonsense once and for all.

Combinations of intel_pstate=active, intel_pstate=passive and intel_pstate=disable were tried with powersave, performance, and ondemand.

Using intel_pstate=active with performance seemed to never enter any kind of power saving mode. Conky seemed to always display at more than 3000 MHz. Likewise with powersave or using acpi-cpufreq (intel_pstate=disable) with performance.

Using either intel_pstate=passive or acpi-cpufreq (intel_pstate=disable) with powersave triggered KDE into launching everything slow. KDE does not seem to like any kind of powersave mode. Nothing crashed but waiting 3 to 4 seconds for everything to launch is mind-numbing.

Using ondemand with intel_pstate=passive or intel_pstate=disable, the latter of which triggers into acpi-cpufreq, seemed to result in palatable results. Everything in KDE launched normally and the Conky display seems sane most of the time.

The intel_pstate=disable and ondemand combination seemed the best possible although not ideal. After many years of using acpi-cpufreq and powersave, time is needed to acclimate to Conky’s CPU frequency display jumping all over more than with powersave.

Yet that too proved futile. Sometime thereafter CPU frequency again skyrocketed. Moving to the conservative governor helped but no explanation was found for the changed behavior.

Before the changed behavior, the cpufreq-info stats showed the CPU frequency staying below 1200 MHz about 60% of the time along with no perceptible affect on desktop performance.

There are no conclusions one way or another. A better trial might be running each of the different combinations for several days while connected to a Kill-A-Watt meter along with plotting CPU fan speed and temperatures.

The statement in the Slackware rc.cpufreq seems incorrect or misleading. Using intel_pstate and performance made no difference with respect to power saving.

Newer is not always better.

Yet Another Example why updating computers is so frustrating.

Something always breaks. Always.

Posted: Category: Usability Tagged: Slackware

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