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 They seemed to be either out-of-date, and no longer worked, or else pulled in egregiuous dependancies.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@waltdnes.org>