Post Syndicated from original https://lwn.net/Articles/906511/

Huge pages are a mechanism implemented by the CPU that allows the management
of memory in larger chunks. Use of huge pages can increase performance
significantly, which is why the kernel has a “transparent huge page”
mechanism to try to create them when possible. But a huge page will only
be helpful if most of the memory contained within it is actually in use;
otherwise it is just an expensive waste of memory. This patch
set from Alexander Zhu implements a mechanism to detect underutilized
huge pages and recover that wasted memory for other uses.