This been discussed to death already here but
"“Software-Based Variable Rate Shading in Call of Duty” presented at SIGGRAPH 2020 (
http://advances.realtimerendering.com/s2020/index.htm) has some interesting thoughts on this topic as well. They present a method leveraging how console hardware handles MSAA to emulate VRS on platforms without hardware VRS support and extra flexibility such as smaller tile sizes
. In addition, they present an optimized way to apply VRS to compute shaders that uses ExecuteDispatchIndirect to ensure only waves with actual work are dispatched in contrast to our brute force method. However, Software-Based VRS also has some trade-offs including implementation complexity and the overhead of a de-blocking pass. One possibility is to use a hybrid of both techniques, switching between VRS techniques based on the characteristics of the rendering pass."
So yeah it seems that software VRS can be as performant as HW VRS but dosent have to be. We dont know. I wouldnt call softawre VRS solution as superior anyway.
This is from 2020 a lot could have chnaged since then, the HW understaning is much better now. But if they managed to develop own VRS software solution that is as good as HW or better then i agree all versions would have it.