Hardware performance

FiringSquad: One of the things that ATI has kind of said, or least they were suggesting at Shader Day is the fact that they can do more floating-point operations than you guys can. How would you respond to those types of statements?

Kirk: Well I guess the first response would be of course they would say that. But I don’t really see why you or they would think that they understand our pipeline, because in fact they don’t. The major issues that cause differing performance between our pipeline and theirs is we’re sensitive to different things in the architecture than they are so different aspects of programs that may be fast for us will be slow for them and vice versa. The Shader Day presentation that says they have two or three times the floating point processing that we have is just nonsense. Why would we do that?

FiringSquad: Could you give us specific examples of where maybe you feel you guys, you mentioned you guys can do some things better than they can, can you give us some specific examples of that?

Kirk: Well one example is if you’re doing geometric calculations with reflections or transparencies and you need to do trigonometric functions. Our sine and cosine takes two cycles theirs takes eight cycles, or seven cycles I guess. Another example is if you’re doing dependant texture reads where you use the result of one texture lookup to lookup another one. There’s a much longer title time on the pipeline than there is in ours. So it just depends on the specific shader and I feel that for the calculations I mentioned are pretty important for effects and advanced material shaders and the types of materials that people use to make realistic movie effects. So they will get used as developers get more used to programmable GPUs and we’ll have less of a performance issue with those kinds of effects.

FiringSquad: Do you feel that fact that you guys, your hardware came out later -- does that also contribute to the initial performance that’s coming out in terms of the DX9 titles that have been benchmarked with?

Kirk: Yeah, I would say that one of the issues is that since our hardware came out a little bit later some of the developers started to develop with ATI hardware, and that’s the first time that’s happened for a number of years. So if the game is written to run on the other hardware until they go into beta and start doing testing they may have never tried it on our hardware and it used to be the case that the reverse was true and in this case now it’s the other way around. I think that people are finding that although there are some differences there really isn’t a black and white, you know this is faster that is slower between the two pieces of hardware, for an equal amount of time invested in the tuning, I think you’ll see higher performance on our hardware.

FiringSquad: So you do think that the initial numbers that have kind of come out really aren’t indicative of final performance.

Kirk: [Yes] I believe. Of course, as I say if other people are commenting on our architecture without any knowledge, I don’t why [their comments on our architecture], why do you think it would be right? You know in our case I haven’t worked with all of the developers, but the ones that I have worked with have seen marked improvements when they start to actually work with our hardware and optimize for our hardware.