The easiest way is probably to look in
<dbdir>/munin-update.stats (on RHEL and Debian, dbdir is
/var/lib/munin). That file contains a line for each host that was checked in the last run. Each line is of the format:
There are three fields, separated by
|s. "UD" stands for something like "update detail"; there's also a "UT" line with the total time it took to update everything, so you should probably
grep '^UD' /var/lib/munin/munin-update.stats. The second field is the host and its categories, in the same format that
/etc/munin/munin.conf has. The third field is the number of seconds it took to get the host's data.
This approach is a little better than grepping through
/etc/munin/munin.conf directly for two reasons: Primarily because munin has include directives so it's possible that not all of your hosts are defined directly in the main config file; and secondly just because the file format is simpler, so it's easier to get data out of it.