The pageinfo metricset reports on paging statistics as found in /proc/pagetypeinfo


Reported metrics are broken down by page type: DMA, DMA32, Normal, and Highmem. These types are further broken down by order, which represents zones of 2^ORDER*PAGE_SIZE.
These metrics are divided into two reporting types: `buddyinfo`, which is summarized by page type, as in `/proc/buddyinfo`. `nodes` reports info broken down by memory migration type.


This information can be used to determine memory fragmentation. The kernel https://www.kernel.org/doc/gorman/html/understand/understand009.html[buddy algorithim] will always search for the smallest page order to allocate, and if none is available, a larger page order will be split into two "buddies." When memory is freed, the kernel will attempt to merge the "buddies." If the only available pages are at lower orders, this indicates fragmentation, as buddy pages cannot be merged.

