FPGA-Accelerated Simulation Technologies (FAST): Fast, Full-System, Cycle-Accurate Simulators

This paper describes FAST, a novel simulation methodology that can produce simulators that (i) are orders of magnitude faster than comparable simulators, (ii) are cycle- accurate, (Hi) model the entire system running unmodified applications and operating systems, (iv) provide visibility with minimal simulation performance impact and (v) are capable of running current instruction sets such as x86. It achieves its capabilities by partitioning simulators into a speculative functional model component that simulates the instruction set architecture and a timing model component that predicts performance. The speculative functional model enables the simulator to be parallelized, implementing the timing model in FPGA hardware for speed and the functional model using a modified full-system simulators. We currently achieve an average simulation speed of 1.2MIPS running x86 applications on x86 Linux and Windows XP and expect to achieve 10MIPS over time. Such simulators are useful to virtually all computer system simulator users ranging from architects, through RTL designers and verifiers to software developers. Sharing a common simulation/design infrastructure couldfoster better communication between these groups, potentially resulting in better system designs.

1. Introduction

The ability to accurately, quickly and easily predict properties of computer systems is useful for computer architects, designers, software developers and users. Simulators provide a window into the inner workings of the computer that helps promote understanding and enable the accurate evaluation of ideas and theories. Because simulators are not subject to the same constraints as a real implementation, they are easier to create, modify and observe.