A Linux 6.15 Performance Regression Hits Modern AMD CPUs

Separate from last week in uncovering a big performance regression on Linux 6.15 affecting workloads like Nginx and that regression getting fixed, I unfortunately discovered another heavy-hitting regression on Linux 6.15. This latest performance regression has been bisected and a possible fix is being thought through by the relevant party, but for the moment has yet to be fixed upstream and affects modern AMD processors.