[$] Recent work in memory tiering

Tiered-memory systems are built with multiple types of memory, each of which has different performance characteristics. In addition to the usual DRAM, a tiered system might also provide faster high-bandwidth memory or slower CXL memory. On these systems, the placement of memory allocations has a significant effect on the performance that a workload will obtain. While work on tiered-memory improvements has been ongoing for years, it feels like the pace has slowed a bit recently. Even so, there are a few efforts underway, but they are facing questions about whether the tiering design makes sense.