Intel's Larrabee Architecture Disclosure: A Calculated First Move
by Anand Lal Shimpi & Derek Wilson on August 4, 2008 12:00 AM EST- Posted in
- GPUs
A Tribute to Michael Abrash: The ISA
Some people idolize athletes. Others gravitate towards entertainers. While Derek is a hockey fan and a musician who loves watching movies, his real passion lead him in a different direction. And he's also going to devolve into first person singular for a minute to tell you a little more about that.
At the time I was a high school student who needed a good project outside the curriculum to teach to our C++ programming class (this was another one of the excellent projects Jo Adams set her students upon). My good friend Tom Macleod and I had just learned enough calculus and advanced geometry to be dangerous: we decided to write a 3D graphics engine in order to learn and teach graphics programming to the class.
To support this endeavor, I spent a bit of cash (well, my parent's cash anyway) on some graphics and game programming books for the occasion, and the one that really stood out (the one that set the course of my life) was Michael Abrash's Graphics Programming Black Book Special Edition. This giant tome contained quite a bit of collected wisdom regarding the art and science of code optimization and graphics programming as well as some great details about the development of Quake.
Not only was his book an incredible source of information and inspiration for me personally, but if there was ever an x86 assembly guru and graphics programming god that could help take the design of an instruction set architecture for Larrabee to a whole other dimension, it is Michael Abrash. And our information indicates that he has done just that.
This isn't to say that others on the Larrabee team don't deserve a spotlight; it's just exciting to see the guy who got me hooked on computer graphics programming (which lead to my interest in hardware) show up on such an impressive graphics hardware design team.
For those who haven't idolized Abrash, his Wikipedia entry helps explain his luminary status in the game industry:
"Michael Abrash is a highly regarded technical writer, and one of the top optimization and 80x86 assembly language programmers, a reputation cemented by his 1990 book Zen of Assembly Language Volume 1: Knowledge. Before getting into technical writing, Abrash was a game programmer, having written his first commercial game in 1982. After working at Microsoft on graphics and assembly code for Windows NT 3.1, he returned to the game industry in the mid-1990s to work on Quake for id Software. Some of the technology behind Quake is documented in Abrash's Graphics Programming Black Book. After Quake was released, Abrash returned to Microsoft to work on natural language research, then moved to the Xbox team, until 2001. In 2002, Abrash went to work for RAD Game Tools, where he co-wrote the advanced Pixomatic software renderer, which emulates the functionality of a DirectX 7-level graphics card and is used as the software renderer in such games as Unreal Tournament 2004."
Intel brought Abrash on as a consultant to help define the Larrabee instruction set. For the longest time, extensions to x86 (e.g. SSE4) were done by Intel engineers at the request of the software community. With every iteration of SSE the game industry was always happier but never truly satisfied with the extensions to x86 that Intel introduced. When Intel set out to define the extensions to x86 that would be used in Larrabee, it sought out visionaries within the game industry to help define that spec rather than creating hardware and defining the ISA internally. One thing we've consistently heard from game developers about Larrabee is that the ISA makes more sense than any other approach they have seen from ATI or NVIDIA. Larrabee's ISA was designed in part by the game industry, for that very industry.
Interestingly enough, while reluctant to go into details about the Larrabee ISA itself, Intel did tell us that fewer than 5% of the instructions are graphics specific. What they found is that creating overly specialized instructions doesn't always do that much good as they can be hard for compilers to use effectively and difficult to hand optimize with as well. Rather, having a good selection of generally applicable and powerful instructions is a better way to go.
One of the advantages of developing the compiler in parallel with the ISA itself is that they can easily test and adapt both as needed to understand how best to balance the ISA. As the vast majority of developers will rely on compilers to generate highly performant code, making sure the ISA is a good fit for compilers is essential. At the same time, because of the renewed interest in software graphics engines Larrabee is stirring up in the Old Guard of real-time 3D computer graphics, having icons like Michael Abrash on the team will help make sure that the ISA is not only compiler friendly but will also be attractive to those who wish to achieve Zen through assembly optimization.
Which brings us to an interesting point.
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erikespo - Monday, August 4, 2008 - link
http://en.wikipedia.org/wiki/Square_%28geometry%29">http://en.wikipedia.org/wiki/Square_%28geometry%29helpful page to take you back to first grade
and excuse my decimal point.. it is 204.49mm total per core or 14.3mm^2
erikespo - Monday, August 4, 2008 - link
Explain.lets use smaller numbers for you 2mm^2 is 2mm by 2 mm or 4 total mm
double that and it is 4mm^2 or 4 mm by 4 mm or 16mm total..
we are talking about area or 2 dimensions not 1 dimension.
Same math applies to the article
MamiyaOtaru - Monday, August 4, 2008 - link
No, you're way off. 2mm² is TWO square millimeters. (a rectangle 1x2 for example). Double that would be 4mm², which could either be 1x4 or 2x2.NUMBERmm² doesn't mean NUMBERxNUMBER mm, it means exactly what it says: NUMBER mm².
Using your smaller numbers: 2mm² is not "4 total mm"; it is TWO mm². Saying it is 4 total mm doesn't even make sense. You _can't_ measure area in millimeters. You measure it in square millimeters, and there are two of them (_2_mm²).
Here's an mspaint visual (if links work: http://img105.imageshack.us/my.php?image=squaremma...">http://img105.imageshack.us/my.php?image=squaremma...
You're so sure you're right on this, it's really depressing :(
darkequitus - Monday, August 4, 2008 - link
I did not appriciate the writer creaming over every digital page they wrote. especially when Larrabee's performance is mainl at the moment based on INtel hype and nothing real.ZootyGray - Monday, August 4, 2008 - link
THANK YOU.Somebody finally said it.
The others prefer Eutopian illusion - aka the curse aka ntel antitrust. ntel has no grafx and the fools in the public buy "inside' and nvid and ati aren't exactly friends of the curse.
welcome to the matrix. wakey wakey
ZootyGray - Monday, August 4, 2008 - link
and a 16 pager on maybe might could be should be = wannabe "employ-boy"- payday ? hooyeh. This is so disappointing for me. Credibility sags to a new low.
strikeback03 - Tuesday, August 5, 2008 - link
Someone whose two posts contain about 10 complete words and no complete thoughts says Anandtech's credibility has sagged to a new low?ZootyGray - Tuesday, August 5, 2008 - link
haha yeh - lots of room for thinking.or - if no thinkeez - ya gots der 16 pg inundation (that's a big word like marmalade) all based on nothing-is-real - you like that kind of brainwash? we don't know anything; but here's the tekspex?
btw - did u get it? the matrix idea? watch the movie. cos here it is. pardon my loaded cryptic literacy.
thx
if you don't get it - well, that's what they want - a world of sleeping mob. never mind, that's just my concern.
The Preacher - Monday, August 4, 2008 - link
I don't really care about how good it will be executing some software renderer but I feel it is going to kick ass in scientific calculations. Matrix operations, FFT/convolution, tremendous bandwidth, double precission... I may write C++/x86 assembly code directly for it and I may put this into a rack of servers and use it through MPI. Give me a compiler with vector intrinsic functions for it and my dreams just came true! :)elerick - Monday, August 4, 2008 - link
I have been a daily reader of another hardware review site for years. I ready nearly every articles that headlines and find many of them quite lacking. Today I got wind of your review for the Larabee. It was very well written and produced an amazing amount of tech knowledge not really commonly reviewed. I'm glad to have found you this site, and I never create an account but today I felt obligated to. Great work.PS: any news on that AMD / Fusion? or is that just them being intimidated by Intel's Larrabee?