Evaluation of Performance on Variable Rate Shading

Abstract: Background. Modern games are becoming more demanding on the hardware, and to counter this, new techniques to ease these demands are developed. One such optimization technique is Variable Rate Shading (VRS), included in the DirectX 12 API. It allows developers to vary the quality of parts of the frame to improve performance. How efficient VRS is, seems to vary as different benchmark tests get various results. This is most likely because of the different scene environments used in the tests. Objectives. To further expand the environments used in VRS benchmark tests, this study will focus on measuring and evaluating the performance of VRS in a lightweight environment that differs from the others. Methods. The method consists of developing a lightweight Direct3D 12 application, implement the VRS technique, and measure performance. For a clear evaluation, several tests are conducted measuring frame time, frame rate, and draw call speed at the different settings using the VRS technique at various resolutions over 1000 iterations. Results. By measuring the frame time, frame rate, and draw call speed with VRS it was possible to collect performance data which is showcased in this study. The study showcases the average performance using 1x1, 2x2, and 4x4 shading rates at 480p, 1080p and 2160p resolution. The average data were compared between shading rates and resolutions to examine the correlation and deviation. As anticipated, the results showed generally performance improvements when using VRS. However, some settings showed inconsistency in deviations between shading rates, and others showed impaired performance. Conclusions. The conclusion drawn from this study suggests VRS improves performance even in lightweight applications, within reasonable boundaries. However, the performance gain was of a lower degree when comparing with other benchmark tests. This suggests VRS be more useful in higher demanding environments.