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Old 24 April 2017, 09:40   #3
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Join Date: Jul 2008
Location: Netherlands
Posts: 278
I did some analysis on this using Intel Graphics Percormance Analyzer ( with a iGPU (HD4000) and additionaly by using Microsoft's GPUView ( with a few graphics cards, both ATI and NVidia.

The general conclusion is that with WinUAE the GPU is occupied for only ~100 - 500 microseconds, i.e. 0.1 - 0.5 milliseconds, per single frame.

So in general I think your previous comment holds

This was tested without any shaders/filters and max 2x2 scaling.

While testing it was interesting to see that the iGPU / graphics cards that I tested ran in their power saving / desktop state when WinUAE is running. Only using "warp mode" made them run at max GPU speed. Generally they run at 1/3 to 1/2 of the GPU speed when in throttled mode.

I guess when using special d3d filters this could lead to a tipping point where the GPU stays in power saving / throttled mode, negatively impacting shader performance.

Using a few utilities that make the GPU clock to the max, the "GPU occupied" time scaled linearly lower versus their higher clocked GPU speed.

Bottom line conclusion is that you were right that it won't make much use putting input on a separate thread.

The only case I can think of where it could possibly make sense would be some very heavy shader/filter, which would probably multiply the above mentioned times several times (especially on lower end hardware)...
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