Remedy on DX12: Matching DX11 GPU Performance Not Trivial on All Architectures; “You’re the Driver Now”
When it launches on April 5, Remedy's Quantum Break will be the second DirectX 12-only game after Gears of War: Ultimate Edition, though we're certainly hoping for a very different result in terms of performance.
A few technical details of their experience with Northlight's implementation of DirectX 12 just emerged from the presentation hosted yesterday by Remedy's Graphics Programmer Ville Timonen, titled Advanced Graphics Techniques Tutorial Day: Developing The Northlight Engine: Lessons Learned.
The slides are now available publicly and there are a few interesting tidbits for sure. For example, in the following slide Timonen mentioned that the developer "is" the driver, under DirectX 12.
That's because DX12 is a lower level API and as such, it requires far more work by the developers than DirectX 11, where the driver played an important role. He also stressed that programmers need to think in separate CPU/GPU timelines and have to be mindful of memory usage and performance.
It seems like DirectX 12 was implemented alongside a DX11 path, and Remedy took care of Xbox One first.
The conclusion is quite a far cry from a ringing endorsement of the new API by Microsoft, too.
The last slide says that in terms of GPU performance, developers can expect to match DirectX 11 if they did things right, but this is not trivial on all architectures. In all likelihood, this is a reference to NVIDIA's current GPU architecture which doesn't meld well with Asynchronous Compute for instance. Moreover, the slide warns that messing GPU memory management can be costly.
In terms of CPU performance, Remedy confirms that it's easy to surpass DX11. We know that DX12 can handle a lot more draw calls, for instance, but truthfully not every game is bound by CPU overhead, as pointed out by the slide.
Overall, this pretty much confirmed what we've seen in the first DirectX 12 games like HITMAN, Rise of the Tomb Raider and Gears of War: Ultimate Edition. Results are mixed to say the least and things like SLI/Crossfire have to be explicitly supported by developers; DX12 is far from the magic API some might have pictured and it will require considerable work from developers in order to completely surpass DX11.
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