Feature Request: Powersaving options


#1

Hi!
I have been using my Note+ for some time now and I found a few things that I would love to see implemented in the future.

1.) One thing I often do is have a very complicated page on the Note+ for a very long time and It feels like a waste of battery to have the Note on all the time, so I would like to propose a power-save option that instead of switching to the “POWER OFF” screen it would continue on the current screen and just add a small icon that indicates that the device has powered off or in “suspend to disk” [1] state.

2.) Another proposal is to be able to read a document in what I would call “super power-save mode”, super power-save mode would temporarily switch from android and reboot in to a very fast booting Linux, like [2] or [3].
Bootup time is between 1-3s depending on hardware etc.
This fast booting system would then directly display the next page in the document and then power off again.
We would have to find good ways to switch back from super power-save mode, for example pressing the power button for 3 seconds can boot normally while just clicking could trigger the next page in the document in super power-save mode eg. boot up -> update screen -> update current page information -> power down.
After the last page is reached then we automatically switch back to android.
We could also evaluate if an automatic “suspend to disk after next page load” is fast enough but this would probably only be a good idea if Android/Linux kernel is patched to work with FastON [1][4], R-Loader [1][5] and implement user-space checkpoints [1][6]

3.) Another type of power-save mode would be to create/use a really fast booting micro OS with a very low memory footprint or baremetal that only implements very basic text reading and annotation functionality and power-saving optimizations. The idea comes as a extension of Samsung Galexys “Ultra power saving mode” or Sonys “Ultra Stamina mode” that boot up a very basic and stripped down version of Android. If the memory usage is low enough we could probably use the automatic “suspend to disk” approach without impacting the flash too much (but implementing [1][4][5][6] on top of the micro OS would be even better).
As I understand it the Note+ and many other of the onyx readers use RK3288 which is the same as the asus tinkerboard, so I would guess that it should not be too hard to continue on one of the efforts made in one of their communities.

Best Regards
/Imp

References:
[1] https://events.static.linuxfound.org/sites/events/files/als13_huang.pdf
[2] _www.datalight.com/products/fast-boot-linux
[3] _www.embeddedarm.com/software/arm-linux-fastboot-ts7400
[4] Swap-before-hibernate: a time efficient method to suspend an OS to a flash drive”, Dr. Shi-wu Lo from OSLab of National Chung Cheng University in Taiwan
[5] “Resume-Loader” developed by 0xlab
[6] Examples of user space checkpoint mechanisms:

  • CryoPID _http://cryopid.berlios.de/
  • BLCR (Berkeley Lab Checkpoint/Restart) _https://ftg.lbl.gov/projects/CheckpointRestart/
  • DMTCP _http://dmtcp.sourceforge.net/ (Has been verified to work with Android 4.0 in “Checkpointing using DMTCP, Condor, Matlab and FReD”, Gene Cooperman, Northeastern University, Boston _https://events.static.linuxfound.org/sites/events/files/als13_huang.pdf