Conservative Not Saving Power?
Originally Posted by chickelnoodensoup
Is the summary in the first post correct with regard to conservative? Is it really "Generally one of the worst governors for saving battery"? Interesting.
I know it seems a little odd. It's because a lot of developers seem to have tweaked conservative to make it feel snappier, but it has resulted in more CPU time at the top frequency.
If you take a look at my new spreadsheet: http://goo.gl/ThVzX
...you can see conservative always uses more power when the screen is on (at least for the four kernels I tested).
There is just one exception where conservative saves more power than other governors, and that is when the screen is off, music is on, deep idle is on, and this only applies specifically to Air Kernel. PLEASE NOTE: Steve Garon does not include deep idle, but is working on it, neither does Eugene, but I've asked him to consider it. For these two kernels, if you are listening to music with the screen off, currently, the best power saving governor is Ondemand.
For people who don't use their phone while off, and don't use many intensive apps, Ondemand is the best power saving choice.
For people who use a lot of CPU intensive apps, SmartassV2 will be the better choice. It will scale more agressively, help prevent lags, and save energy being wasted through these delays.
If you listen to music with the screen off, and your kernel supplies deep idle, the best power saving governor is SmartassV2 (except for the case of Air Kernel, see above). This is because it keeps the CPU close to the most efficient frequency: 400MHz.
I hope that covers anything. If I've made any glaring errors in my reasoning, please let me know.
Choosing a Governor
Variety is the spice of life, so try them all! While Mathkid95 swears by Ondemand, developers Eugene373, morfic, and steve.garon all vetted this work and agreed that the highest performing CPU governor is likely to offer battery savings through the race-to-idle
principal. Eugene added that finding the right I/O scheduler to combine with your governor will make a big difference too. Extra thanks to Steve for providing the kernel on which I based this test, and all his valuable input! The I/O scheduler for the test was cfq, and note: governors have settable parameters which may vary between developers.
Choosing a Scheduler
I/O schedulers perform differently depending on the governor you are using. I've investigated this using the six most popular CPU governors (vote here
) vs the six available I/O schedulers in Eugene's kernel, and the four available in r_data's kernel. All governors are based on either ondemand, interactive, or conservative. Recommended reading is available here: schedulers
also for governors
Schedulers tested against these popular governors:
SmartassV2 - interactive variant, and winner of the governor test.
LulzactiveV2 - interactive variant
Lazy - Ezekeel's governor, ondemand variant
Performance - included as a reference for high scores