[gmx-users] the CPU of REMD

[Albert]

hello:
   I've got a qeustion the CPU for replica exchange. it said the REMD 
should be performed by command:

mpiexec -x -np 8 mdrun -s sd_.tpr -multi 8 -preplex 1000

the above command have 8 different temperature and it specify 8 cores. 
Does it mean the mdrun will use 1 core (8 in all) for each subjob or 8 
core (64 in all) for each sub job?

thank you very much.
Albert