[$] Proactive reclaim for tiered memory and more

Memory reclaim in Linux is largely a reactive practice; the kernel tries tofind memory it can repurpose in response to the amount of free memoryfalling too low. Developers have often wondered if a proactive reclaimmechanism might lead to better performance, for some workloads at least,and optimal use of tiered-memory systems will likely require more activereclamation of memory as well. At the 2022 Linux Storage,Filesystem, Memory-management and BPF Summit (LSFMM), Davidlohr Buesoled a brief session on the topic.