Intel has made several changes to its processors since it switched to a heterogeneous core architecture. These include adding the Thread Director, removing AVX512 support, and (soon) abandoning hyper-threading (also known as Simultaneous Multithreading). This isn’t news, but it is the first time the chipmaker’s internal documentation of the 15th Gen Arrow Lake CPUs indicates so. We’ve reported on this topic in the past, with a detailed breakdown of why hyper-threading is going away (and Rentable Units are coming in).
Internal documents leaked by YuuKi_Ans show that a pre-alpha Arrow Lake sample lacks hyper-threading. Each of the “Lion Cove” P-cores is explicitly mentioned as having a single thread, the same as the “Skymont” P/Atom cores. Interestingly, the sample is also unstable when running the P-cores, due to which they are disabled from the firmware.
The interesting question is whether Arrow Lake will architecturally support hyper-threading, and if so, will it be disabled from the BIOS like AVX512 on early 12th Gen chips? The decision to remove SMT without a suitable replacement feels rather unnecessary. Was hyper-threading removed because it didn’t provide any tangible performance advantages or because early plans for Rentable Units didn’t pan out?
