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Comment by wging | Hacker News Reader

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wging·

"8-core processor with 66 threads per core." 66*8 = 528. Why 66 is not explained.

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Look at slide 6, "Die Architecture" (https://www.servethehome.com/wp-content/uploads/2023/08/Inte...).

The diagram shows 8 gray boxes (in 2 columns of 4). Each gray box is a core.

Above that is a detailed view of what each core looks like. There's a middle section labeled "Crossbar", and above that are 3 boxes labeled STP, MTP, and MTP. Below that are another 3 identical boxes. So each core has 4x MTPs and 2x STP.

What are those? The text of the same slide says MTP is "Multi-Threaded Pipelines" with "16 threads per pipeline" and STP is "Single-Threaded Pipelines" with (self-evidently) 1 thread per pipeline.

And 4 * 16 + 2 * 1 = 66, so 66 threads per core.

Good one. These presentations are like 30 min each so it is hard to stay on top of all of them.

Yes it is. They have four 16 thread pipelines, and two single thread pipelines per core. 4*16=64 and 64+2=66

So, why do they consider that 1 core? Isn't that more like a "compute complex" of multiple cores, as seen on zen 2, but with different core architectures attached instead of 4 cores of the same design?

I'd be inclined to call them multiple cores myself, but if they all share the same pipe to main memory that would be a plausible reason to call them all the same core.

Maybe 2 higher-powered primary threads + 64 aux threads or something. I don't know how that makes sense as part of a single core but I don't have a better guess.

That's what it is, as shown on slide 6 (Die Architecture). Personally I would call this 16 big cores and 32 throughput cores but for some reason Intel is calling it 8 cores.

Maybe they just couldn't fit 67?

66 = 64 slow GPU-like threads + 2 very fast CPU-like threads

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