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Larrabee more efficient than GPUs at rasterisation
Author: Ben HardwidgePublished: 30th March 2009
Intel's forthcoming Larrabee architecture is based on x86 cores, but is apparently still efficient at rasterisation tasks.
Larrabee, Intel’s first foray into the world of discrete graphics since the abysmal i740, has been a hot talking point in the PC gaming business, not just because it’s another competitor in the GPU business, but because it also relies on software rendering via x86 CPUs. However, while Intel has given us very few details about the architecture, little is known about how the chip will actually perform, which is what makes games programmer Mike Abrash’s recent session on Larrabee at GDC particularly interesting.
VentureBeat attended the lecture, in which Abrash revealed some of his experiences of the performance of Larrabee in comparison to traditional GPUs. According to VentureBeat, Abrash claimed that, despite using software rendering, Larrabee can in fact be more efficient than traditional GPUs when it comes to performing rasterisation tasks.
The site also says that Abrash claimed that Larrabee’s performance will be above 1TFLOPS, although this computing milestone has already been passed by current traditional GPUs such as the Radeon HD 4870. Interestingly, Abrash also noted that the “raw graphics performance” of Larrabee isn’t likely to be as fast as other graphics chips, but praised Intel’s chip for its power-efficiency and flexibility.
The latter appears to be particularly appealing to programmers such as Abrash, who worked on the original Doom, Quake and Half-Life games, before moving to RAD Game Tools. According to VentureBeat, Abrash described Larrabee as the “most fascinating graphics architecture” that he’d seen in 15 years, with the chip’s cores making it more flexible than a standard GPU pipeline.
By using multiple x86 processors, many people have noted that Larrabee could also be used for ray tracing as well as rasterisation, although it would need a tremendous amount of computing power to do this effectively in real time.
However, VentureBeat also quotes a memo apparently sent by Nvidia CEO Jen-Hsun Huang to Nvidia employees, which says that Intel could potentially breach the cross-license between the two companies by releasing Larrabaee.
“In our countersuit,” says the memo, “we assert our belief that we are licensed to build chipsets for Intel processors. In a pair of agreements signed in 2004, we negotiated for rights to build chipsets. In exchange, Intel obtained a cross license to our valuable patents. Today, Intel is using technologies that we invented in their integrated graphics chips. And they will soon integrate Nvidia patented technologies into their CPUs and upcoming Larrabee processors.”
Could flexibility become more important than raw graphics performance in the future of graphics chips? Let us know your thoughts about Intel’s Larrabee graphics chip in the forums.
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On topic:
I just can't wait to see how Larrabee performs. Although I think it'll be designed to sell in the mainstream market rather than in the high-end segment. Still... interesting.
//edit: Just a quick question: Who writes the articles at Venturebeat? 10 year olds? :| Or is just aimed at people who have hardly any detailed knowledge of the technology behind graphics cards?
i don't see how Intel, who is a new player can out-perform nVidia/ATI in their own games.
It has already been said they won't be. People need to stop assuming Intel plan on usurping ATI and nVidia in one fell swoop.
Give Intel some credit, what they have seems very interesting, and has a lot of potential.
I don't think Intel will fail on the latter. They might not be as effective as ARM as we've learned but they're pretty good at that.
I'm sure Intel can really push Larrabee by integrating these cards just like they push their horrible IGPs, but how fast can they do that and will they get far enough among the hardcore crowd to convince major developers into going through all the development hassle? Development is already a very costly process and the financial crisis is making many studios close, suggesting they don't have spare cash to spend on such risky projects.
In 2007 it looked like this:
http://media.arstechnica.com/news.media/graphics.png
Source: ArsTechnica
And according to JPR's Q208 report:
Source: i4u.com
If you remove all the crappy intel IGPs that the shipped with the bulk of the office machines out there. I think that a geforce 4 mx is maybe on par with the best IGP intel has.
The situation at the moment is quite scary with the current intel lawsuits, it almost looks like intel is trying to block the competition from using its technologies while still keeping hold of their tech ( SLI on x58, AMD64 extensions on C2,I7)...
I'm holding thumbs that intel loses those suits and is made to pay the consequences for their anti-trust actions.
On the larrabee issue, larrabee might be almost as efficient at rasterization as newer GFX cards, but what will it matter, by the time larrabee launches (assuming a delayed launch) we'll have GFX cards with hardware tessellation units and DX11.
Nevermind the insane power requirements a 32 core larrabee card will need, estimations of this if intel uses a 45nm process, is around 300w just for the cores, once you include memory and other subsystems, you'll be looking at a 400w power draw. And from all account those cores will be kept pretty busy even for basic tasks.
Personally I'm holding thumbs for larrabee to be a epic failure but then Intel will just strong arm OEMs into supplying the cards to their customers, just like with their atrocious IGP chipsets, that 45% of people are using today!
I was speaking of discrete graphics, where Intel has no presence and S3 can be disconsidered.
Therefore, we're talking about a market of 31.4% + 18.1% = 49.5%.
As such, NVIDIA has 31.4% / 49.5% = 63.4343434343434% of that market, with the rest left to ATI. My memory of Valve's hardware surveys ain't that bad, eh? =)
But that's still approximate as we would also need to split NV and ATI IGPs, but that won't change my point.
As Larrabee is based on x86 architecture and instructions, and a part of the agreement with AMD is to share x86 and developments from it (e.g. x86-64, otherwise known as AMD64), doesn't this mean that AMD could make their own Larrabee compatible part if this whole architecture takes off?
And if it does, where does this leave nVidia, who doesn't have an x86 licence?
although they say it's going to be x86 compatible, i highly doubt that, it's probably just part of the x86 instruction set, just enough for ray-trace and current generation.
The question is: Will they want to make x86 graphics cards? It's a very risky change and there's a lot of market inertia that should hold back the architecture from industry-wide adoption. If it were a two-man race (out of the three men NV, AMD and Intel) or if x86 was guaranteed to be better, than they would be scrambling to get it done as well. Yet, if only Intel tries the push, AMD and NV could remain comfortably earning cash on current rasterisation cards and leave the costs of change to Intel. Once it does change the industry (if it does), they can jump in. With a bit of delay, for sure, but a tiny fraction of the costs and almost no risk. Sounds like a more reasonable plan considering you have a multibillion-dollar company at stake.
Assuming x86 turns out to be better, yes, AMD could hop in, as well as VIA, I'd guess. NVIDIA would be left out as they kind of already are, justifying their seeking of x86 with VIA and internal developments.
I disagree - that's nearly 10w a core. You can run a full Core 2 with cache at that level etc at that power level. Remember these are dumb simple cores with in-order execution and a lot of the power hungry bits missing, just like Atom. I'm guessing they'll be looking at around 2w a core giving a total near to 80-90w all up. Still a lot, but it depends on what the load is like and what amount of useful work you're getting out of the other end.
Ooops, I meant a single Core 2 core.
here's some links:
http://news.cnet.com/8301-13512_3-10024280-23.html
http://en.wikipedia.org/wiki/Larrabee_(GPU)
I'm sorry if i misunderstood but did you just saw that a single C2 core runs at around 10w? so that would mean a quad core will only use 40w? Something doesn't sound right there...
Aslo the larrabee cores are as azreal pointed out p54 cores (which are pretty old). There has also been major speculation that the card will have up to 48 or more cores for the high end cards. Those cards are gonna be monstrosities.
Seeing as at 1ghz, it takes 24 of those core to run FEAR (and old game) at 60FPS. If larrabee launches with 24 cores at lets say 3ghz, which is another estimation of the operating speed, we might be looking at around 100FPS. (don't tell me its gonna be at 180fps, since by now people should realize nothing scales linearly) which isn't exactly revolutionary since my 8800gtx could already pull that off.
I'm also curious to see MultiAA performance, Anistropy performance, HDR performance on these cards, till now intel has been awfully quiet...
For power consumption the Larrabee cores will be more akin to the Atom, rather than a Core 2, from what I can gather.
I agree with your argument. Only if it takes off, and there is every chance that it won't. You only have to look at PhysX to see that it is a big IF.
Intel has only gone down the multi-core x86 route because it doesn't know how to do anything else. Interviews I've read with game developers would indicate to me that they aren't too thrilled by Larrabee, and Intel would surely need to partner with a developer to create that must-have halo product (not a pun, but like Halo did for the Xbox, and PhysX doesn't have) to drive adoption.
And it has to be a great product too, pretty and crap won't sell your mega-$$$ graphics card.
lets assume each core @ 3ghz has a TDP of around 10w (seeing as a 1.6ghz atom has a TDP of around 4w-8w depending on the family)...
we have 32 of these cores on a larrabee card: 32 * 10 = 320W, now add voltage regulator circuitry and RAM power and other components - lets guess and say around 50w (just a guess seeing as a gtx260 core is rated at 180w TDP and uses around 230w full load)
we're now sitting on 370w for a 32 core card...
lets be optimistic and say it'll use 7w per core (unlikely since they want speeds of 3ghz) - we're left with a card that uses 274w, which is the same as a gtx285...
It's all speculation and guess work on my end tho, so chances are I'll be proved wrong... (I hope not, I want to see intel fail! intel740 style!! )
The Larrabee, what a stupid name, was 'benchmarked' at 1 GHz and IIRC, Intel according to the rumours, are aiming for 2GHz. This makes sense given that the broadly similar Pentium M architecture never run much above 2Ghz.
Intel could score big with Larry, with its combo GPU/CPU Clarkdale, especially if they are able to design a chip that offers enough grunt for mainstream gamers and some fancy EIST to turn the GPU off in desktop mode to reduce power consumption.
The Wii demonstrated that if there are ulterior benefits, people are willing to overlook the lack of outright power, well maybe not Bit-Techers:D
A 3 GHz Larrabee with 32 cores can issue 16 instructions per clock, plus can do fused multiply add, doubling GFLOPS.
3 * 32 * 16 * 2 = 3072 GFLOPS
370W for 3072 GFLOPS. Yes please.
If it could do Fused Multiply Add and another instruction such as Add/Mul (like nvidia's cards) they'd be able to claim another 50% on top of that. This is extremely unlikely however.
A 16 core Larrabee @ 2 GHz will break the TFLOP barrier though, and even the pessimists will agree that a 16 core version at 2 GHz is very likely.
Larrabee what a stupid name? As opposed to going through ever number combination in existence like nvidia? It's a codename btw, its not meant for consumption by the ignorant.
Get over the x86 cores too. They are going to be something like Atom. They aren't meant to be fast, they provide an easy to program platform. The speed comes from the 16 issue SIMD AVX cores (LRB equivalent of SSE). SIMD is no different to all the graphics cards on the market today. All nvidia's cards are SIMD, and ATI's too.
I'm not sure why people get their knickers in a twist so badly and say how Nvidia/ATI are pro's. There's not a lot to be pro about. GPU's are relatively basic processors compared to CPU's. The art is feeding all the cores with the required data.
FLOP means floating point operations, and 16 instructions per clock doesn't mean 16 FLOPs per clock. because floating points are hard to do, it may need to break into micro-code and executed in many steps.
the nVidia shader pipelines, however, are optimised for calculating floating point units with all the necessary bits and bobs to do it in one clock cycle, that's the advantage of RICS architecture, and that's why x86 is not the answer to everything.