MegEnta is our parallel/distributed simulation execution infrastructure for the simulation of models with very large number of (on the order of a million) entities. Our design of MegEnta consists of two distinct modules:

1. TiCOON --- A high-performance general-purpose object-oriented parallel simulation executive that is based on a novel micro-kernel approach.
2. HOPPERS --- A novel ultra light-weight process abstraction which also supports shared-memory semantics.

Together, the two modules will be able to support the modeling and simulation of large-scale models. A set of real-life large-scale applications, such as PCS network models, will be developed using the MegEnta framework, and these applications will serve as capability demonstrations.

TiCOON: Time Control--Open & On-line

TiCOON is a new object-oriented parallel/distributed simulation executive that is designed with the goals of scalability, auto-configurability, extensibility and portability. TiCOON is different from other simulation executives in its approach to extensibility and its federatability (ease of interoperating in a federation of heterogeneous simulation executives). Extensibility and federatability are facilitated using a novel micro-kernel approach to simulation process management that is analogous to the concept of micro-kernel operating systems (as opposed to monolithic kernels).

TiCOON incorporates a ``Time Control'' mechanism that can simultaneously support different synchronization schemes (such as optimistic and conservative). It is ``Open'' in the sense that it allows model-specific optimizations and extensions, using object-oriented techniques (inheritance and polymorphism), while requiring no changes to the executive proper. Object-orientation is used both in the simulation API as well as in the implementation of the executive. It is ``ON-line'' in the sense that it is federatable, supports incorporation of GUIs and visualizations, and is capable of both interactive and batch-mode execution.

TiCOON incorporates several parallel simulation features which are not only important for achieving the goals of MegEnta, but also have application outside the goals of this project (for example, in efficiently supporting multicast semantics in parallel simulation). These features include

1. efficient implementations of ``Read-only'' and ``Query'' event abstractions
2. addition of ``wide virtual time'' to support application-defined ordering of simultaneous events, facilitating repeatability and fairness
3. facilities for supporting prefetching remote state, and for temporary blocking of a logical simulation process.

HOPPERS: Dynamic, Ultra Light-weight Processes

We have developed a novel concept called ``Hoppers'' (which we also refer to as ``Active Events''). Hoppers are very light-weight simulation processes that enable the simulation of very large systems. The HOPPERS module can be considered as a ``middle-ware'' that supports the Hoppers abstraction, and the module sits between the simulation executive (TiCOON) and the application.

The Hopper concept attempts to support two important desirable features for modeling and simulation:

1. A form of shared-memory semantics for simulation object interaction
2. Capability for the simulation of a large number of (on the order of a million) model entities.

Previous parallel simulation research focussed primarily on two extremes, namely, pure event-oriented interaction, and pure process-oriented action. In contrast, our work on HOPPERS attempts to find a middle ground between the two extremes, capturing the advantages and eliminating the problems of the two.

Also, HOPPERS is different from conventional shared-memory systems because new issues arise due to optimistic processing in optimistic-style simulation approaches, whereas such issues are absent in general shared-memory systems.

Summary

The design of MegEnta, consisting of TiCOON and HOPPERS, is completed. We have also started the implementation of TiCOON; the work-in-progress currently runs on shared-memory multiprocessors (SGI PowerChallenge, Sun UltraSPARCs) and uniprocessors (Sun SPARCs, SGI Indigos and DEC Alphas).

Publications

• Coming soon.