Working on many native memory customer cases, I miss the following metrics:

periodic:
- Linux, process: vsize, swap (how much was swapped out for this process, not of the whole system)
- Linux, process: different RSS subtypes (shmem, anon)
- Linux+glibc: memory outstanding and retained (very important, even if it's an estimate), number of trims
- Linux, process: number of OS-side threads (important, if much larger than JVM threads, especially for scenarios where we run embedded in a custom launcher)

Event driven:
- Linux+glibc: an event for native heap trim operations, telling me when, how much RSS recovered, and duration