Linux 5.16's New Cluster Scheduling Is Causing Regression, Further Hurting Alder Lake

Linux 5.16-rc1 is coming out later today and already I'm seeing some fallout in the new kernel's performance... In particular, bad news for Alder Lake that is already seeing the Linux performance trailing Windows 11 seemingly due to the lack of Thread Director integration right now in the kernel and any other missing optimizations around Intel's hybrid architecture. A new feature of Linux 5.16 is unfortunately having unintended regressions for Alder Lake with at least the flagship Core i9 12900K. Here are the results from the latest kernel bisecting that uncovered this latest upstream slowdown.