freebsd stable - May 2006 - how to increase on correct way to avoid "collecting pv entries -- suggest increasing PMAP_SHPGPERPROC"

Running freebsd 6.1 stable on amd dual opteron 4G RAM

how to correctly calculate to increase the options SHMMAXPGS value?

did some googl'ing but could not find a clear instruction how to go on.

Currently apache2 is causing the "collecting pv entries -- suggest 
increasing PMAP_SHPGPERPROC" messages.

any hints or point-outs would be very appreciated.

Thanks!

patrick