947942 - Evaluate power consumption of HwComposer and OpenGL composition on gonk

Status: RESOLVED WONTFIX

(Firefox OS Graveyard :: General, defect, P3)

Description

[Sotaro Ikeda [:sotaro]]

b2g uses HwComposer and OpenGL to compose gfxLayers. In general, we talked HwComposer's pwer consumption is lower than OpenGL one. Bug we do not know clarly how we could save poser consumption by HwComposer than OpenGL one.

To get a better UI responsiveness, we are going to use more layers than before like the following.
https://groups.google.com/forum/#!topic/mozilla.dev.gaia/wI-jbAwucFA

Current b2g devices supports only limited number of layers rendering. If the number of layers increase than before, HwComposer rendering is fallbacked to OpenGL rendering. In this case, we could get more UI responsiveness, but we might degrade power consumption. To think about trade off between power consumption and UI responsiveness. We need to know about the power consumption of HwComposer and OpenGL composition.

I am not sure if there is already such data in public. For the time being, the following use cases might be necessary.
- Show home screen
- Video Playback

Comment 1

[Sotaro Ikeda [:sotaro]]

Sorry, the above need info was my mistake. I just want to add them to cc.

Comment 2

[Sotaro Ikeda [:sotaro]]

jhylands, is there already such data to evaluate the power consumption between HwComposer and OpenGL?

Comment 3

[Jon Hylands [:jhylands]]

Sotaro, we would need a version of each, so we could run a test with HwComposer, and then, with nothing else changed, run the same test with OpenGL, and compare the overall power consumption for each run.

Comment 4

[Sotaro Ikeda [:sotaro]]

B2g v1.2 hamachi seems better. v1.2 is stable and hamachi is used as a standard device.

Comment 5

[Nicholas Nethercote [inactive]]

Sotaro, is this bug worth keeping open? gsvelto suggested it might still be important.

Comment 6

[Sotaro Ikeda [:sotaro]]

(In reply to Nicholas Nethercote [:njn] from comment #5)
> Sotaro, is this bug worth keeping open? gsvelto suggested it might still be
> important.

It seems better to close the bug. About hw composer usage, chip vendors and we care only to the following use cases as whether devices do full hw composition.
- Full screen camera preview
- Full screen video playback

And We already know that LCD back light is major source of power consumption.

Comment 7

[Nicholas Nethercote [inactive]]

Thank you for the information.

Closing as per comment 6.