limit on PV entries

[n dhert]

FreeBSD 8.2-RELEASE
>From time to time, I get in /var/log/messages
 kernel: Approaching the limit on PV entries, consider increasing either
the vm.pmap.shpgperproc or the vm.pmap.pv_entry_max sysctl.

this started a few weeks ago, never had that before, don't have it on other
FreeBSD 8.2-RELEASE systems.

- What does this mean?
- And how to increase either of the two and to what level ?

$ sysctl vm.pmap.shpgperproc
vm.pmap.shpgperproc: 200
$ sysctl vm.pmap.pv_entry_max
vm.pmap.pv_entry_max: 3256966