Benchmarking in Vulkan or Dx12 is still a bit of a pain in the NAS, but PresentMon makes it possible to conduct accurate FPS and frametime tests without reliance upon FRAPS. July 11 marks DOOM's introduction of the Vulkan API in addition to its existing OpenGL 4.3/4.5 programming interfaces. Between the nVidia and AMD press events the last few months, we've seen id Software surface a few times to talk big about their Vulkan integration – but it's taken a while to finalize.

As we're in the midst of GTX 1060 benchmarking and other ongoing hardware reviews, this article is being kept short. Our test passes look only at the RX 480, GTX 1080, and GTX 970, so we're strictly looking at scalability on the new Polaris and Pascal architectures. The GTX 970 was thrown-in to see if there are noteworthy improvements for Vulkan when moving from Maxwell to Pascal.

This test is not meant to show if one video card is “better” than another (as our original Doom benchmark did), but is instead meant to show OpenGL → Vulkan scaling within a single card and architecture. Note that, as with any game, Doom is indicative only of performance and scaling within Doom. The results in other Vulkan games, like the Talos Principle, will not necessarily mirror these. The new APIs are complex enough that developers must carefully implement them (Vulkan or Dx12) to best exploit the low-level access. We spoke about this with Chris Roberts a while back, who offered up this relevant quote:

The Vulkan API has completely taken over AMD's low-level Mantle application program interface, somewhat of a peer to Microsoft's DirectX 12.

It's a competitive space. Mantle tried to push the industry toward more console-like programming – and we mean that in positive ways – by getting developers “close to the metal.” Low-level APIs that bypass the insurmountable overhead of DirectX 11 are the key to unlocking the full potential of modern hardware; DirectX 12 and Vulkan both get us closer to this, primarily by shifting draw calls off the CPU and reducing bottlenecking. GPUs have grown so powerful in their parallel processing that they can assume significant workload that was once placed upon processors – this benefits gamers in particular, since the majority of our workloads are more easily pushed through the GPU.

As a part of our new website design – pending completion before CES – we've set forth on a mission to define several aspects of GPU technology with greater specificity than we've done previously. One of these aspects is texture fill-rate (or filter rate) and the role of the TMU, or Texture Mapping Units.

When listing GPU specifications, we often enumerate the clockrate and TMU count, among other specs. These two items are directly related to one another, each used to extrapolate the “texture filter rate” of the GPU. The terms “Texture Fill-Rate” and “Texture Filter Rate” can be used interchangeably. For demonstration purposes, here is a specifications table for the GTX 980 (just because it's recent):