Author Topic: AVX vs AVX2  (Read 1536 times)

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Offline ShivanSpS

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I compiled a .exe from source today, VS 2017 compiled it by default on AVX2, and at first i did notice less fps drops while playing, i did a test and i was right, altrought this may not be the best test escenario it will have to do.

I ran this test 3 more times, always with the same result, less fps drops and more memory usage on AVX2.

I did notice the light is not exactly the same altrought it has the same launcher config, maybe there is something else on 3.8.1 that could be causing this?
« Last Edit: March 26, 2018, 08:59:17 am by ShivanSpS »


Offline DahBlount

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The difference in lighting is likely due to the move from Blinn-Phong to GGX shading.

We've actually been aware of the fact that AVX2 has fewer fps drops than AVX, there are multiple reasons for this, and some of them also coincide with increased memory, but that's a fairly normal tradeoff for better performance (ie. better performance can mean more memory usage).
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Offline ShivanSpS

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Oh this is nice, for a moment i trought it was a "placebo" effect, but you can notice the change in game.


Offline AdmiralRalwood

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DahBlount was actually the first person to notice the performance difference when I gave him an AVX2 build for testing something else; the resulting graph (of the FPS differences) was included in the GitHub PR adding AVX2 support.
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That testing looks nice,  but the GPU-Usage on AVX2 drops a few time to 0% ?!  It also uses less gpu-memory, but more RAM. Is AVX2 using more Cache-like mechanics ?
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