[Discuss] linux cpu governors

[Rich Pieri]

On 1/12/2016 10:20 AM, Dan Ritter wrote:
> ....
> For contemporary Intel processors, the frequency is controlled by the
> processor itself and the P-states exposed to software are related to
> performance levels.  The idea that frequency can be set to a single
> frequency is fiction for Intel Core processors.
> .....

Indeed. Frequency is proportional to power draw and power draw is keyed
to process load. Even if you were to pin the clock speed at max, when
idle it will have an idle power draw and the actual frequency will be
proportional to that draw. That's why I'm seeing 3.6GHz in Open Hardware
Monitor on my 4790S but only ~18W power draw with a light load. When
idle it drops to 800MHz with a power draw of about 2W. Under full load
the measured CPU core frequencies remain at 3.6GHz but the power draw
runs up to just shy of 65W.

I prefer using the conservative governor. It has the same low end as
powersave but it ramps up to full under load more quickly but not as
rapidly as the performance governor which goes from minimum to maximum
almost instantly.

Also, while underpowering won't cause problems directly it can cause the
hardware to become unstable under load and crash which can lead to data
loss and possible physical damage to mechanical components.

Also, 180W is not ridiculous. My notebook gets by with a 230W brick.
There's an option for a 330W brick for more power-hungry configurations
and a option for a second ganged 330W brick for hard-core overclockers.
Yeah. 650+ watts for a notebook. *That's* ridiculous. :)

-- 
Rich P.