On FreeBSD top(1) utility, although having much less command line switches and options is in fact much more powerful than one that comes with your favorite Linux distribution.
Maybe one day I decide to publish an in depth write up about it but until that day comes here’s one hint. To show only processes that are running within specific jail launch top:
top
press:
J
enter your jail name:
examlejail
Voila, you have only processes within that specific jail listed. To show up processes from all jails, instead of typing in name of the jail simply type in + sign.
Now that I better think about it, to learn more about top:
man 1 top
FreeBSD man pages are also far better than Linux ones ;-)