> Honestly I don't understand why there's not something like a 256 core ARM laptop
The high power ARM cores aren’t that small. If you took the M2 and scaled it up to 256 cores, it would be almost 7 square inches. You can’t just scale a chip like that, though, so the interconnects would consume a huge amount of space as well. It would also consume over 1000W.
The latest ARM chips are great, but some times I think the perception has shifted too far past the reality.
7 square inches would also include an enormous GPU and tons of accessories.
The actual cores are about .6/2.3 mm², and local interconnects and L2 roughly double that.
So with just those parts, 256 P-cores would be about 1.5 square inches, and 256 E-cores would be about half a square inch. And in practical terms you can fabricate a die that's a bit more than a square inch.
Of course it wouldn't use 1000 watts. When you light up that many cores at once you use them at lower power. And I doubt a 256 core design would have all that many P cores either.
As a rough estimate, you could take the 120mm² M1 chip, add 28 more P-cores with 110mm², 220 more E-cores with 300mm², 128 more MB of L3 cache with 60mm², 100mm² of miscellaneous interconnects, and still be on par with a high end GPU.
That sounds doable but is pushing it. A 128 core die, though, has nothing stopping it except market fit.
even a 128 core part made like that will perform pretty atrociously. scaling up the core count without scaling the cache count means you have a lot of cores waiting for memory. also when you have 128 cores, you almost certainly need more memory channels to have enough bandwidth.
Could we make the chips go slower like around 1Ghz? Maybe that is not feasible with the current software architecture to achieve great user experience.
The high power ARM cores aren’t that small. If you took the M2 and scaled it up to 256 cores, it would be almost 7 square inches. You can’t just scale a chip like that, though, so the interconnects would consume a huge amount of space as well. It would also consume over 1000W.
The latest ARM chips are great, but some times I think the perception has shifted too far past the reality.