how does tuned work behind the scene for power saving

[rexxy-sasori]

I am new to tuned and try to use it to regulate power consumption of my server. I saw words like ondemand | powersave in the profiles. Do these refer to the cpufreq governors? How does tuned work behind the scene in adjusting core/uncore frequencies. Any help is greatly appreciated

[yarda]

Uncore support is currently worked on #576.

If you mean the following line from the powersave TuneD profile:

governor=ondemand|powersave

It means governor is set to ondemand and if not possible/supported/available it will fallback to powersave governor.

Generally, the powersave TuneD profile is very performance throttled. For optimal power consumption/performance the balanced profile is usually better choice. For good performance the throughput-performance is usually the best (it is also the default profile on RHEL/CentOS for servers). For work servers you can e.g. switch to powersave profile during off business hours and back to throughput-performance on business hours or you can keep it on balanced and it will try to balance performance/power automatically according to the current load.