[$] The multi-generational LRU
One of the key tasks assigned to the memory-management subsystem is to
optimize the system's use of the available memory; that means pushing out
pages containing unused data so that they can be put to better use
elsewhere. Predicting which pages will be accessed in the near future is a
tricky task, and the kernel has evolved a number of mechanisms designed to
improve its chances of guessing right. But the kernel not only often gets
it wrong, it also can expend a lot of CPU time to make the incorrect
choice. The multi-generational
LRU patch set posted by Yu Zhao is an attempt to improve that
situation.