Unity 2x MSAA has huge affect on performance

AndyB
Contributor

Unity 2x MSAA has huge affect on performance

I've found that turning on 2x MSAA has a huge performance impact, way more than I would expect. 


To investigate I created a new Unity project (see below for versions), created an empty scene and set the cameras in the WaveVR prefab to solid color clear mode.  I then connected the Snapdragon profiler and  found something that seems very strange.  The fragments shaded per second value goes up a lot when MSAA is turned on:

MSAA disabled:  Approx  340 million fragments / second. 
MSAA 2x :       Approx 1700 million fragments / second. 
MSAA 4x :       Approx 2400 million fragments / second

The first value makes sense and covers the distortion pass (2880*1600 * 75 = 345.6M).
But just turning on 2x MSAA increases the number of fragments shaded by 5x.  And with 4x MSAA it's rendering 7x the number of fragments.

 

Can this be right?  I can't see why the number of fragments would increase at all. Nevermind this much.

I'm porting a game from the Oculus Go, where we use 4x MSAA without any problems and I know that switching between 2x and 4x made very little difference for us.  So it's strange to see such a huge impact here.

 

Versions:
Unity : 5.6.3f1
Wave SDK : Reproducted on 2.1.8 and 3.0.2
Focus system : 1.69.623.3

 

Vive Staff

Re: Unity 2x MSAA has huge affect on performance

Hi @AndyB ,

 

Thanks for you sharing, and we'll also do some experiments internally and see how we can share with you soon.

 

razoredge
Pioneer

Re: Unity 2x MSAA has huge affect on performance

We can confirm @AndyB's findings as well! FPS jumped by 50-100% by changing only this quality setting...