Open Stack

I'm planning to build a openstack nova installation with older
hardware. These servers obviously doesn't have the same hardware
configuration like memory and cores.
It ranges from 2 core and 4GB memory to 16 core and 64GB memory. I
know that there are different scheduler, but I'm not sure which one to
choose.
The simple scheduler tries to find the least used host, but the amount
of used cores per host (max_cores) is a constant, which doesn't work
for me.
Maybe the least cost scheduler would be the right one? But I'm not
sure, because I did not find any documenation about how to use it.

Cheers,
Christian