To a great extent, memory management is based on making predictions: which
pages of memory will a given process need in the near future?
Unfortunately, it turns out that predictions are hard, especially when they
are about future events. In the absence of useful information sent back from
the future, memory-management subsystems are forced to rely on observations
of recent behavior and an assumption that said behavior is likely
to continue. The kernel’s memory-management decisions are
opaque to user space, though, and often result in less-than-optimal
performance. A pair of patch sets from SeongJae
Park tries to make memory-usage patterns visible to user space, and to let
user space change memory-management decisions in response.

Source: LWN.net – [$] Memory-management optimization with DAMON