2 cpus per node complications

• The system only allocates/accounts whole nodes

• There may be reasons to use only 1 cpu/node

• PBS should be asked for either -lnodes=N:ppn=1 or -lnodes=N:ppn=2

• When running serial applications remember to spawn to instances per job (per node)

• The two cpus share, among other things, memory (size+bw), /disk/local (size) and interconnect (bw)