Efficient modeling of preemption in a virtual prototype

Abstract

A virtual prototype combines a hardware model with hardware/software cosimulation to support the development and debugging of embedded software before a hardware prototype is available. Existing techniques for hardware/software cosimulation execute the software either on an instruction set simulator for accuracy, or on the simulator host processor for increased performance. On the host processor, timing is either completely ignored or approximated using timing annotations in the code. Although preemption (interrupts) can strongly influence the timing, it is rarely modeled to avoid a performance degrading that would make the virtual prototype unusable, especially for real time signal processing software simulations which is already time consuming as such.We propose a technique to accurately model preemption and its effect on software timing in a simulation based on host code execution. Our technique has been implemented in the TIPSY C++ library for executable system modeling; pseudo C-code for this implementation with several optimizations is included in this paper. With this implementation, a preemptive scheduler model can easily be created or taken from a library and inserted in a system model without changing the original code to observe the effect of preemption on the system behavior.0-7695-0668-2/00 $10.00 ã 2000 IEEE

Virtual synchronization technique with OS modeling for fast and time-accurate cosimulation

“…They report that the accuracy was within 20% and this is due to the limit of host code execution with delay annotation approach. Cockx [4] also proposed a similar way of modeling of preemption. In his codesign environment, TIPSY, to reduce the context switch between software threads due to preemption, out-of-order execution of software threads is allowed.…”

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Virtual synchronization technique with OS modeling for fast and time-accurate cosimulation

“…They report that the accuracy was within 20% and this is due to the limit code [I11 K. Hagen and H. Meyer, "Timed and Untimed hardware execution with delay annotation approach. Cockx [4] also software co-simulation: application and efficient…”