Over the past few months, Microsoft has been steadily releasing details on its upcoming DirectX 12 graphics API set. We know that it will be a significant improvement in performance and efficiency over the current implementation and that it will be built into Windows 10. What we don’t know much about is the actual performance improvements beyond the numbers that Microsoft and its graphics partners have revealed, until now.
Anadtech has obtained a new version of Oxide’s Star Swarm demo that is designed to stress DirectX 12 capabilities to its limit. It puts a massive workload involving a range of effects and element draw calls on the GPU to test how well it performs under the circumstances. AMD and NVIDIA have also provided Anandtech with the necessary WDDM 2.0 drivers that enable DirectX 12 in the latest Windows 10 Technical Preview (Build 9926). Since DX12 works on current graphics cards, Anandtech used a range of existing graphics cards from AMD and NVIDIA.
One of the most important factors in improving performance in games is better CPU scaling. If a DirectX-based game doesn’t efficiently delegate tasks that are better handled by the CPU to the CPU, then things can start to lag. Microsoft looked to eliminate this CPU bottleneck from occurring by allowing games to have more of a say as to what tasks get delegated where. This can be especially beneficial when CPU’s with multiple cores and threads are involved.
The low-level API’s in DirectX 12 also allow for better GPU utilization as games get better access to the hardware. Looking at the numbers below, DirectX 12 can result in up to triple the performance gains over DirectX 11. That’s huge; you would go from playing a game as if it were a PowerPoint presentation to it being as smooth as butter by just upgrading your OS and letting the latest drivers install themselves. Of course, synthetic benchmarks don’t always represent actual “real-life” in-game numbers but it gives you an idea of the potential that game developers can exploit.
Another important factor is power consumption. DirectX 12 ensures that the CPU and GPU work together in perfect harmony, like a fine-tuned engine. And now that the CPU is no longer bottlenecked, the GPU doesn’t find itself idling and waiting for the CPU to finish processing tasks, it’s constantly running now along with the CPU and this drives up power consumption. Although as you can see the numbers below, the increase in consumption isn’t as high as you would expect considering the massive boost in frame rates you saw earlier, so it’s certainly a small price to pay for the gains.
It’s important to keep in mind that DirectX is still under development, and Microsoft noted that there are a few known issues with memory management and other bugs that cause performance regressions. The software giants and its graphics partners are still working closely together to optimize the software and hardware to better work together, so as time passes between now and the time Windows 10 is ready, both the performance and power consumption figures should improve even further. Should game developers make the most out of DirectX 12, it should make gamers jubilant.
Further reading: DirectX, DX12, Microsoft, Windows 10
