Simulator Modes

  A simulator can be executed in five modes:

1. CEP: In this mode, during the simulation, each thread always has a simulation status that is non-deterministic, irrespective of what is determined by its request list. Additionally, the simulation uses only the conditional event protocol (CEP) for EIT advancement.
2. NMP: In this mode also, each thread always has a simulation status that is non-deterministic, but the simulation uses only the null message protocol (NMP) for EIT advancement.
3. CEP+NMP: In this mode also, each thread always has a simulation status that is non-deterministic, but the simulation uses both the conditional event protocol and the null message protocol for EIT advancement.
4. CEP+NMP+Det: This is the regular simulation mode. In this mode, each thread has a simulation status that is deterministic whenever so determined by the thread's request list. Additionally, the simulation uses both the CEP and the NMP for EIT advancement.
5. Det or Fast: This is the fast simulation mode. In this case, each thread always has a simulation status that is deterministic, even when its request list requires it to be non-deterministic. The consequence is that the CEP and NMP never need to be executed, and hence the simulation is fast, but its prediction of target program execution time may be incorrect since messages are not accepted in simulation timestamp order, but in the order in which they physically arrive. Consequently, for example, the same simulator may make different predictions when run sequentially and when run in parallel on two host processors. The use of this mode will become evident subsequently.