Windows8 sensors perf issue with Touch object

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Post » Sat Oct 13, 2012 8:31 pm

@Ashley:

It looks like the Touch object is instantiating accelerometer and inclinometer sensors even if the game is really not making use of those sensors.

This potentially will lead the OS to turn the sensors On and resulting in perf issues and unnecessary power drain - for every game which uses Touch object.

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Post » Sun Oct 14, 2012 1:03 am

Is there really power drain? I did not see anything about that in MS documentation, and I assumed it was a non-issue because other devices (iOS and Android) have their accelerometers and inclinometers always on, and that has never seemed to be an issue. Do you have an official reference for this you can forward me to?
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Post » Sun Oct 14, 2012 11:03 am

With my knowledge of the driver stack, the OS does indeed have to do extra work pumping up the data from lower stack to application layer - so it is definitely not free.

Furthermore, http://blogs.msdn.com/b/b8/archive/2012/01/24/supporting-sensors-in-windows-8.aspx has a reference to this topic:

"...Each active sensor on a system draws power, and sending data up the stack consumes both memory and CPU time." If you read further, the sensor fusion helped "minimize" the power/perf impact but there will still be some impact since it is never free.

Hence unless it is required, we should not register for sensor API callbacks.
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Post » Tue Oct 16, 2012 12:01 am

I assume the battery usage from sensors will be negligable compared to the CPU/GPU use from a game which tends to run both at capacity on mobile devices. Considering this has never come up before as an issue on iOS or Android devices, I'm happy to treat Windows 8 the same and leave them always on. Thanks for the suggestion but I think this should be closed as won't fix.
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