[$] Proactively reclaiming idle memory

Shakeel Butt started his 2019 Linux Storage, Filesystem, andMemory-Management Summit session by noting that memory makes up a big partof the total cost of equipping a data center. As a result, data-centeroperators try to make the best use of memory they can, generallyovercommitting it significantly. In this session, Butt described a schemein use at Google to try to improve memory utilization; while the need forthe described functionality was generally agreed upon, the developers inthe room were not entirely happy with the solution presented.