There is no such thing as 4 E-cores = 1 P-core when we compare performance.
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Comparing 13900K(8P+16E) to 7950X is fair comparison.
(Absolute) Performance has nothing to do with it! Execution resources are shared between each 4-core cluster. Intel is only changing this in an upcoming Xeon release.
All current designs are 4E = 1P. Intel has officially stated this!
One of the reasons Intel went with their hybrid design was that each big core required a single ring stop. Intel couldn’t easily release a 12-16 core chip because it would add too many stops to the ring. So what did they do? they made each quad core cluster share a ring stop, which allowed them to add more cores. And it worked.
That is one of the big reasons why there was a regression from 10 -> 8 cores for Alder Lake. It was to make room for the “e” cores. Intel could’ve released a 10 core part, but found that despite the cores sharing a ring stop (among other things) they could still perform sufficiently for client workloads.
4 “e” cores are “about” the size of a “P” core.
4 “e” cores will perform well in multicore workloads, but may struggle with some throughput stressing workloads due to limited caches and shared ring stops. If I ever get my hands on a 14900k I will write a benchmark to illustrate the strengths/weaknesses of Intel’s approach.
Intel Xeons use a higher latency meshed-based design btw, so they aren’t subject to limits.
AMD has not disclosed their design, but AnandTech has speculated on it. I won’t.
That is why the 8P+32E rumors aren’t very credible. Unless Intel has improved their design, Those extra 16 cores are adding several more ring stops, which will raise latency between cores and limit overall throughput (tl;dr diminishing returns based on number of cores added)
They could move everything to a mesh, but they would be at a competitive disadvantage. I suspect they will eventually get there, but not without other innovations.
The x86-64 architecture as a whole is on the edge of an evolution as well, and both Intel and AMD have their own visions of what that looks like.