rusage_src ~tags is a metrics source that reports data gathered from
kinfo_mem_src ~tags is a metrics source which reports data gathered from sysctl ctl_kern.kern_proc.kern_proc_pid.pid on FreeBSD (which returns a kinfo_proc (see
sys/user.h)), on Linux
/proc/self/statm are used for the collection.
The data provided are virtual size, resident set size, text, data, and stack size, copy-on-write fauls, running time (in microseconds), and uptime.