参考手册:
For multithreading to be effective in model evaluation, the number of active
devices or elements should meet certain requirements.
The condition for model evaluation to be multithreaded is ONE of the following:
■ MOSFET > = 64
■ BJT >= 128
■ Diode >= 128
■ VCCS >= 128
■ VCVS >= 128
■ CCCS >= 128
■ CCVS >= 128
■ or parameter expressions >= 64 (parameter expression evaluation is
parallelized)
If the circuit lacks the required number of active devices, HSPICE automatically
uses a single thread.