Host-Compiled Multicore System Simulation for Early Real-Time Performance Evaluation

Abstract

With increasing complexity and software content, modern embedded platforms employ a heterogeneous mix of multicore processors along with hardware accelerators in order to provide high performance in limited power budgets. To evaluate real-time performance and other constraints, full system simulations are essential. With traditional approaches being either slow or inaccurate, so-called source-level or host-compiled simulators have recently emerged as a solution for rapid evaluation of the complete system at early design stages. In such approaches, a faster simulation is achieved by abstracting execution behavior and increasing simulation granularity. However, existing source-level simulators often focus on application behavior only while neglecting the effects of hardware/software interactions and their associated speed and accuracy trade-offs. In this article, we present a host-compiled simulator that emulates software execution in a full-system context. Our simulator incorporates abstract models of both real-time operating systems (RTOSs) and multicore processors to replicate timing-accurate hardware/software interactions and to enable full system cosimulation. An integrated approach for automatic timing granularity adjustment (ATGA) uses observations of the system state to automatically control the timing model and optimally navigate speed versus accuracy conditions. Results as applied to industrial-strength platforms confirm that OS- and system-level effects can significantly contribute to overall accuracy and simulation overhead. By providing careful abstractions, our models can achieve full system simulations at equivalent speeds of more than a thousand MIPS with less than 3% timing error. Coupled with the capability to easily adjust simulation parameters and configurations, this demonstrates the benefits of our simulator for early application development and design space exploration.