My experience with event based power management tools and governor tuning
I asked a few days ago about governor settings but then set out to explore it myself. The aim of what I was doing was to make my truesmart last a full day of normal use. I am trying to make my truesmart my primary device, so a full days use is important (especially as Omate have not yet shipped my second cradle!)
Over my first couple of days with the Truesmart it was lasting about 9 hours of moderate use (Moderate use to me is having it on my wrist all day, showing people who ask, talking to my girlfriend on hangouts, checking facebook and updating a few apps). This meant that it was usually running out of juice on the walk home from work. And that really was not good enough. Yesterday, with all my modifications I was able to go out until midnight, and come home to 40% battery. So these are the tools that after trying a few I think are worthwhile.
1. Bluetooth on call https://play.google.com/store/apps/d...asper.btoncall
Does what it says, when someone calls BT turns on, pairs with my headset and lets me pick up. In reverse I dail a number, count to 3 and select the bluetooth speaker, usually before they have picked up. The result is that BT goes from being about 17% of a days charge to not registering on my battery meter.
2. Lean data - https://play.google.com/store/apps/d...eqtic.leandata
Wifi is on when screen is on or on charge, when screen is off it can be set to pulse on and off for set time periods (i set 1 on and 10 off). The result is that Wifi goes from being 20% of a days charge to being about 4%
So once I was done with the two most obvious methods I had two main culprits of power usage.Cell Standby (41%) and Phone Idle (37%). Short of some baseband tuning 2g off (I live in Korea, there is no 2g) there is nothing that can be done with cell standby. So I looked to governor settings to reduce Cell standby and maybe even improved on screen battery performance. I tried a few apps, but this was by far the best
3. CPU tuner - https://play.google.com/store/apps/d...droid.cputuner
Usual warnings here, this app is playing with some fairly low level stuff, it may stuff up your device and it does have a few bugs.
This app actually makes the first two redundant,
, I've left the links for people that don't want to mess with governors, they are now off my watch. But the best thing this one does is that it allows you to set modes for different CPU governor tweaks on the fly. YOu will want to read this next: http://forum.xda-developers.com/show....php?t=1736168
On the truesmart we have 5 Governors available:
Performance - all on
Powersave - all (yes all) to lowest power
On demand - all scale frequency to power demand
Userspace - something odd that lets compatible apps set it ignore it
Hotplug - like on demand but can turn off one CPU completely
And from what I can tell we have 3 frequencies available on a 1Ghz chip (598, 806 and 1001).
You will almost always want to use hot plug unless you are benchmarking or manually switched one of the cores off as the others lack the ability to halt the second core automatically, so power is usually better, even than powersave. You also get to set the percentage of load that the frequency is upped and a powersave vs performance bias which I believe impacts how long the governor should be at that load before stepping up to the next level and how eager it is to step back.
I use uniform profile and set the following modes:
On screen or lock screen - hotplug - a small powersave bias and threshhold up at 50
Screen off on call or charging - powersave - max cpu 598, 2nd core disabled
People might find my charging profile odd, but I figure the device isn't overly usable in the cradle so why not have it charge as fast as possible, I tried performance but it got hot. With all this set, my phone idle battery usage now tracks up at about 2/3 the rate of my cell standby and there really is no loss in end user performance. The governor tweaking probably gets me and extra hour or 2 usage over the day.
After everything was done I have gone from 9 hours of charge with my usage profile to being able to last a full 18 hour day and still having room to spare. 36 hours off charge is not off the cards, so that is a four fold improvement. Have a play and let me know if it helps.