undervolting (e.g. skylake) in linux

I've been using iuvolt for a few months and I wanted to say thanks for this convenient linux tool.

I understand every similar utility provides a way to lower voltage by a fixed offset (say, -100 mV).
I was wondering if you guys would know of a way to specify a relative offset (say, -20%), or a linear offset (say, from -100 mV for lower voltages or cpu frequencies, to -200 mV for higher ones). Because I noticed stronger undervolts are supported when cpus run at higher frequencies, so there's definitely room for improvements here (wrt power consumption and temperatures at higher loads).

 

I had similar thoughts, as my CPU could as well go to to about -210mV while on full load* vs. "only" -180mV (in relative offset mode b/c at low clock speeds the voltage is already quite low).
I've only seen these two modes: relative and absolute voltage.
And the CPU changes these states extremely frequently, so I can't imagine that a tool can handle that on OS level.

The only sensible thing I've read about undervolting/OC is making several modes:
1. Your "general purpose" mode uses the maximum relative offset you can achieve. So you'll have the lowest possible voltage in idle mode.
2. For high performance, you set a absolute voltage for your maximum clock speed (maximum stable UV like you mentioned). This means in idle it will draw a bit more power, but you enable this mode only when you want to use maximum performance. Maybe you can somehow enable this mode automatically, when some CPU intensive APP starts ...

(* Another thing I've noticed: This maximum UV of -200 or -180 doesn't work with GPU workloads / while gaming. Only -160mV is stable.)

 

Indeed I could find a way to create a few profiles, with undervolts and governors. And manually switch between them depending on computer load. I wish I had time and skills to create a utility that would automagically switch to the proper profile.
Governors and thermald already manage cpu load balance and frequencies, so I thought maybe a utility like tlp could be modified to manage undervolt as well. But of course I could be wrong, and anyhow I don't think tlp devs would agree to implement an unsupported feature such as undervolting.