ACM Transactions on Programming Languages and Systems (TOPLAS)
SIGMOD '87 Proceedings of the 1987 ACM SIGMOD international conference on Management of data
Parallel discrete event simulation
Communications of the ACM - Special issue on simulation
A formal approach to recovery by compensating transactions
Proceedings of the sixteenth international conference on Very large databases
Time Warp simulation in time constrained systems
PADS '93 Proceedings of the seventh workshop on Parallel and distributed simulation
GTW: a time warp system for shared memory multiprocessors
WSC '94 Proceedings of the 26th conference on Winter simulation
State saving for interactive optimistic simulation
Proceedings of the eleventh workshop on Parallel and distributed simulation
SIMULATION OF PACKET COMMUNICATION ARCHITECTURE COMPUTER SYSTEMS
SIMULATION OF PACKET COMMUNICATION ARCHITECTURE COMPUTER SYSTEMS
Proceedings of the 38th conference on Winter simulation
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We introduce a latency hiding mechanism that enables computationally intensive operations to be utilized in real-time interactive environments. In most cases, real-time interactive environments preclude calculations that run slower than real-time. Our approach called optimistic I/O (OIO) schedules anticipated operations in advance so that their results are ready when needed. An associated roll-back scheme enables recovery whenever an unexpected real-time input forces the cancellation of scheduled operations. Optimistic I/O is implemented in a parallel simulation executive and is evaluated by demonstrating (1) feasibility in a virtual environment application and (2) effectiveness in an analytical framework. The feasibility of OIO is demonstrated by integrating a computationally intensive image generation application called the synthetic scene generation model (SSGM) into an interactive environment (SSGM is used by the Ballistic Missile Defense Organization researchers to produce phenomenologically correct images for testing missile and satellite sensor systems). Effectiveness is evaluated by analytically examining the impact on the quality of an animation sequence as the probability of user interaction increases. We observe that speculative computing is advantageous in applications that include expensive computations, especially when the polling frequency for user interaction is high with respect to the computational period and the probability of interactions is low. Potential applications of optimistic I/O include: Interactive virtual environments for hardware-in-the-loop testing (e.g., missile tracking sensors); high-fidelity visual simulations for human training; and robotics applications where motor control commands require a significant number of computations, but where the presence or absence of objects in the environment may change which computations are necessary. All these applications share the requirement that a computationally intensive task (such as image generation) must be completed at real time rates in response to external inputs.