Android tablet computation slowing down with screen off

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Message 1840139 - Posted: 5 Jan 2017, 15:30:00 UTC
Last modified: 5 Jan 2017, 15:45:42 UTC

I have a tablet (Quanta Gigaset QV830 - SDK:17 ABI: armeabi-v7a) running Android 4.2.2 and crunching on all 4 cores 24/7 and recently I noticed that computation appears to be considerably slower whenever the screen is turned off (in ~half an hour a task progressed by about 0.3 % with screen off and 1,3 % with screen on, it was connected to a power supply in both instances). Is this because the tablet goes into some kind of power saving mode whenever the screen is turned off, throttling the processor (it's not "going to sleep", though)? Or something to do with the BOINC app (7.4.53) or something (the event log doesn't show anything to that effect)? I enabled to always have the screen on through the developer options, but I would of course prefer otherwise for obvious reasons.

I searched BOINC projects as a whole for someone else with this problem, but all I could find is people wanting to get rid of sleep mode (though mine's not doing that) or keeping the screen on indefinitely (which I know how to do).

Any input appreciated.
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Message 1840145 - Posted: 5 Jan 2017, 16:03:57 UTC - in response to Message 1840139.  

Did you check runtimes on the same task? There can be a huge difference in runtimes between different tasks, depending on the AR (angle range) and other factors.
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Message 1840146 - Posted: 5 Jan 2017, 16:05:08 UTC - in response to Message 1840145.  

Yes, it was the same task.
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Message 1840150 - Posted: 5 Jan 2017, 16:25:53 UTC

Maybe you can find something that records processor performance level - I think there was something on xda-developers for that but that's years ago.

It would be reasonable to assume that your tablet was throttling down when screen is off. There probably are tools that would change it.
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Message 1840168 - Posted: 5 Jan 2017, 17:21:13 UTC
Last modified: 5 Jan 2017, 17:26:00 UTC

Thanks, I'll try that.

Just did another check with another task and it's the same performance ratio.
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Message 1840216 - Posted: 5 Jan 2017, 20:34:02 UTC - in response to Message 1840168.  

Most probably it's tablet's firmware.
I encountered 2 different tablet models already that completely stop computations with screen OFF.
Would be good to decouple CPU throttling and screen light OFF, but seems on those models they bound together.
Not all Android devices behave in such way.
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Message 1840232 - Posted: 5 Jan 2017, 22:29:39 UTC - in response to Message 1840216.  

Most probably it's tablet's firmware.
I encountered 2 different tablet models already that completely stop computations with screen OFF.
Would be good to decouple CPU throttling and screen light OFF, but seems on those models they bound together.
Not all Android devices behave in such way.

I found that out with my first android phone. A MyTouch 3G Slide. It would go from a max of 600MHz to only 300MHz with the screen off. So I run it with the brightness turned all the way down. My Samsung Galaxy S4 and Tab S2 seem to run full speed with the screen off or on with BOINC projects.

There might be CyanogenMods for some devices that would disable or allow the user to control the CPU throttling.
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Message 1840308 - Posted: 6 Jan 2017, 9:41:16 UTC

Yeah, I've been considering CyanogenMod for the tablet. I also have a Motorola XT1068 with an up-to-date Android version and it doesn't appear to throttle.
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Message 1842430 - Posted: 15 Jan 2017, 18:15:04 UTC

So it seems that the clock screensaver does not cause any throttling and should be better for the display too. Seems like a good compromise.
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Message boards : Number crunching : Android tablet computation slowing down with screen off


 
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