This patch adds the Free Memory Fragmentation Index (FMFI) metric to the vm_phys subsystem.
The FMFI metric measures the degree of physical memory fragmentation for a given order by using metadata from the buddy allocator freelists.
Its value ranges from arbitrary negative values up to 1. A negative value implies that there is ample memory to serve an allocation request of the given order.
A value between 0 (no fragmentation) and 1 (highly fragmented) indicates the degree of physical memory fragmentation.
This work was sponsored by the Google Summer of Code program.