BSD::Sysctl offers a native Perl interface for fetching sysctl values that
describe the kernel state of BSD-like operating systems. This is around 80
times faster than scraping the output of the sysctl(8) program.

This module handles the conversion of symbolic sysctl variable names to the
internal numeric format, and this information, along with the details of how
to format the results, are cached. Hence, the first call to sysctl requires
three system calls, however, subsequent calls require only one call.