John Carmack Interview: GPU Race, Intel Graphics, Ray Tracing, Voxels and more!

Carmack Speaks

In our interview with John Carmack at Quakecon 2011 we talked about hardware trends and how consoles are able to keep up with PCs.

Last week we were in Dallas, Texas covering Quakecon 2011 as well as hosting our very own PC Perspective Hardware Workshop.  While we had over 1100 attendees at the event and had a blast judging the case mod contest, one of the highlights of the event is always getting to sit down with John Carmack and pick his brain about topics of interest.  We got about 30 minutes of John’s time over the weekend and pestered him with questions about the GPU hardware race, how Intel’s intergrated graphics (and AMD Fusion) fit in the future of PCs, the continuing debate about ray tracing, rasterization, voxels and infinite detail engines, key technologies for PC gamers like multi-display engines and a lot more!

One of our most read articles of all time was our previous interview with Carmack that focused a lot more on the ray tracing and rasterization debate.  If you never read that, much of it is still very relevant today and is worth reading over. 

This year though John has come full circle on several things including ray tracing, GPGPU workloads and even the advantages that console hardware has over PC gaming hardware.

Note: Due to popular demand, we are going to have a transcript ready (likely tomorrow) as the third and 4th page of this article.

First up on our list of topics was the importance of mathematics in the world of game and game engine design. Carmack stated that though his math background was a bit overstated in some cases he was able to build the engines we all know and love with a basic, applicable knowledge of high school topics such as geometry and calculus. The key is knowing how to apply these things to a problem that you haven’t seen before as opposed to being able to answer a question on a test. Of course, as engines have developed into more and more complicated pieces of software the need for higher level mathematics are required for physical simulations though you can still solve much of the world’s problems (at least in a software sense) by time-slicing and iterating.

The topic of the GPU hardware race came up early in our talk and the response Carmack gave us was pretty interesting. Stating “I don’t worry about the GPU hardware at all, I worry about the drivers” seemed to be a reiterated point. This became very apparent to id Software while developing RAGE where even though the PC had truly an order of magnitude more horsepower than the consoles, it struggled to keep up with the “minimum latency”, get feedback here, update data there, etc and do it all to maintain a 60 Hertz frame rate. DirectX 11 and multi-threaded drivers might have helped things but he still claims that they are far from the solution he envisions: direct surfacing of the memory system. The process of updating a textures on the PC is on the order of “tens of thousands of times slower” than on the Xbox 360 and PS3. AMD did implement a “multi-texture” update specifically for id Tech 5 which should help, but from the interview you can tell that Carmack really does want more done on this topic.

One interesting side effect of this talk – Intel’s integrated graphics actually has impressed Carmack quite a bit and the shared memory address space could potentially fix much of this issue. AMD’s Fusion architecture, seen in the Llano APU and upcoming Trinity design, would also fit into the same mold here. He calls it “almost a forgone conclusion” that eventually this type of architecture is going to be the dominant force. You might remember our discussion of this topic with Josh’s analysis of AMD’s Fusion System Architecture – it would appear that AMD has a potential ally on its side if they are paying attention.

Carmack still thinks the Intel integrated graphics is on feature parity with other integrated options and that people are going to be surprised in the not-too-distant future when the “free” graphics you get with your Intel CPU is good enough to play pretty much any game you want. He admits of course that the software and driver implementations from Intel need a lot of work and he has “high hopes” that with the shared memory potential there Intel will push forward with this “closer to the metal” mentality. There is also the outlet for console developers to more directly develop for integrated graphics than for discrete graphics (as it would be more similar to the console architectures) and games might run faster on integrated than low cost discrete solutions.

Larrabee was discussed as well – and though a couple of years ago it was thought this might be the “sweep” architecture across all the coming generation of consoles, it clearly didn’t meet the performance requirements to be successful yet. Instead, it seems obvious that there are again going to be multiple architectures on the pending console designs and there could be “strong contenders” based around the ARM architecture. But any next-generation console NEEDS to be a 64-bit architecture and with ARM just now integrating 64-bit designs for the first time, it leads us to believe we are a couple of steps away from seeing ARM in your next gaming console.

Carmack does hope that Sony avoids the Cell architecture all together due to the difficulty in development.