Intel Opens Up About Larrabee

[Rob Williams]

Intel's Larrabee architecture has been on the mind of many enthusiasts for the past few months, but sadly, Intel hasn't released any specific performance data today. What they have revealed are the base mechanics of the architecture and other tasty tidbits to whet our appetites.

Intel today takes a portion of the veil off their upcoming Larrabee architecture, so we can better understand its implementation, how it differs from a typical GPU, why it benefits from taking the 'many cores' route, its performance scaling and of course, what else it has in store.

You can read the full article here!

[Kougar]

Just wow. IF the hardware is even close to delivering, then this is going to be the future. No doubt about it, fully programable super-computing cards.

GPUs, got people's attention with their supercomputing ability for specialized tasks. NVIDIA's CUDA especially, after it went from languishing as a marketing slide and demo video for longer than a year before almost overnight it turned into a major deal. Universities everywhere have built single computers with multiple GPUs and now receive better performance than supercomputing clusters they utilized previously. At much lower prices. Folding@home has literally exploded, NVIDIA and EVGA GPU-only teams appeared out of the blue and climbed through the ranks of folding teams that had been folding since F@H's inception 8 years ago, and single-handedly upset the rankings. It made the PS3 look mediocre, despite teams of PS3 folders doing the same just prior to CUDA launching with F@H support.

Long paragraph short, GPU's got people to realize CPUs are no longer the way to go for raw performance. With a fully programmable "GPU" set to debut, there will not be a single hurdle left for people to begin porting applications over. Fully programmable in one of the better known coding languages, this is the start of really big things.

Rob, because you mentioned SIGGRAPH in your article, I found this tidbit hidden in the Larrabee wiki. They give sources for it as well.

On August 12, 2008, Intel will present a paper describing Larrabee at SIGGRAPH. [17] The paper is said to contain a comparison of performance between Larrabee and Core 2 Duo, which reveals that the single-threaded performance of one of Larrabee's cores is roughly half that of a "Core 2" core, while the overall performance per watt of a Larrabee chip is 20× better than a Core 2 Duo chip.[18]

Now, some of my thoughts. A 1Gbit bus is rather insane... no wonder they are having difficulties with the PCB. Just look at what adding a 3rd memory controller to Nehalem did to X58 motherboards, manufacturers have to add two extra PCB layers if they wish to make use of the third controller with six banks of DDR3 memory.

Fuzillia (Not the most reliable, I know) has this article out about how Larrabee is currently a 12-layer 300w card. This seems reasonable considering Larabee isn't going to launch for another year however, emphasis on cutting it down to production size comes last in the engineering process.

But one only needs to look at ATI's first 512bit ring-bus memory GPU, R600, to get an idea of what I am thinking about here. If that was not scary enough, look at NVIDIA's first 512bit memory bus GPU, the GTX 260. Larrabee is going to be a huge "multi-core" die regardless of 45nm or 32nm process size when it launches, and the card complexity is still going to dwarf GTX 260.

The performance may certainly be worth it. I can't wait.

[Kougar]

I can't resist a double-post. I apologize if this is considered hijacking, since technically this section is for discussing TechGage articles...

After reading TechGage's article I went over to Anandtech since I particularly enjoy Anand Lal Shrimpi's hardware & design dissection articles.

From above I was talking about having a 1024bit ring bus is going to mean incredibly huge amounts of die size by itself. So I was already wondering if Larrabee would be making the GT200 core look small. Partly into his article I got to thinking about the actual # of cores Larrabee would likely launch with due to this reason...

Ironically (and partly why I enjoy Anand's articles so much) he explores this idea on page six. Surprisingly, it is more cores than I was expecting, but as he isn't factoring in other things like the 1024bit ring bus that y'all mention, I think 64cores is likely going to be the absolute max, and could very well be less. The again with Intel making cores the size of Itanium (~596mm^2 90nm), which is significantly larger than GT200 it's possible. Larrabee is going to be a beast.