[SR-Users] Children, PKG_MEM and IMS

Hi all, i'm a little bit confused about the #children/PKG_MEM mechanism: in my setup (a simple IMS core with one P-CSCF, one I-CSCF, one dispatcher and 2 S-CSCFs) i wish to manage the highest possible #calls, but i don't know which is the ideal setup. I mean, i'm running all this components in VMs (with mem = 2048MB and smp = 8) inside a desktop machine with RAM = 32 GB and 8 processors; is it worth to define #children = #processors and setting an high value of PKG_MEM (for example 128MB) or use an higher #children (for example 64) with less PKG_MEM (for example 16MB)? Someone could explain me better how the mechanism works? Thank you, Andrea