[GTALUG] "ondemand" CPU governor not recommended for newer Intel machines

[Walter Dnes]

  I've been putting together scripts that run under bash+ash to control
CPU settings.  I was unhappy with current solutions.  They seemed to be
either out-of-date, and no longer worked, or else pulled in egregiuous
dependancies.  In the course of researching stuff for my scripts, I ran
across a 2-year-old Phoronix article
http://www.phoronix.com/scan.php?page=news_item&px=MTM3NDQ which
referenced a Google+ conversation at
https://plus.google.com/+TheodoreTso/posts/2vEekAsG2QT

  Summary... "ondemand" worked great for notebook CPUs from 10 years ago,
but...

> with modern Intel processors, the ondemand CPU governor is actually
> counterproductive because waking up to decide whether the CPU is idle
> keeps it from entering the deepest sleep states, and so (somewhat
> counterintuitively) the performance governor will actually result
> in the best battery life.

  I don't know if the above also applies to the "conservative" governor.
I put together an interactive script and an automated script.  I was
thinking along the following lines...
* notebook runs at "powersave" by default
* run a wrapper script
* wrapper script kicks up to "performance" setting
* launches the job you want done (kernel compile or whatever)
* drops back down to "powersave" mode after the job is finished

-- 
Walter Dnes <waltdnes at waltdnes.org>