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Flexible and Formal Modeling of Microprocessors with Application to Retargetable Simulation. Presented By : Min Chen. Authors: Wei Qin Sharad Malik. Objective. M odeling environments based on precise semantics that can be used for rapid generation of detailed processor simulators
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Flexible and Formal Modeling of Microprocessors with Application toRetargetable Simulation • Presented By : Min Chen Authors: Wei Qin Sharad Malik
Objective • Modeling environments based on precise semantics that can be used for rapid generation of detailed processor simulators • Microprocessor simulation • Instruction set simulators (ISS) • Emulate the functionality of programs • Micro-architecture simulators • Provide performance metrics, functionality of programs
Four important characteristics • Efficient • Expressive • Declarative • Productive Operation State Machine (OSM) Formalism A flexible and formal microprocessor model that is properly balanced in terms of the above characteristics.
Related Work • Operation-centric : nML, ISDL, EXPRESSION • Hardware-centric : MIMOLA, HASE, Asim, Liberty • Special Attempts: LISA, UPFAST, BUILDABONG
Operation State Machine Model • OSM • Token and Token Managers • Language • Director
Language – Four primitive transaction • Allocate • OSM Request token from a manager • Inquire • Inquire about the resource • Release • Request to return a token • Discard • Discard a token
Director • Ensures that the behavior of the model is deterministic. • Scheduling rules: • State transition occurs at most once for each OSM at each control step. • State transition occurs as soon as an outgoing edge has satisfied condition. • State transition along a higher priority edge is preferred.
Modeling Microprocessors • During the interval between two control steps, the hardware modules communicate with one another and exchange information with their TMIs. • TMIs for the 5 pipeline stages. • Register file contains a TMI mr
Common Control Behaviors • Structure Hazard • Data Hazard • Variable latency • Control Hazard
Case Study • StrongArm • Average speed 650k cycles/sec vs. SimpleScalar tool-set at 550k cycles/sec • PowerPC • 250k cycles/sec on a P-III 1.1GHz desktop, 4 times that of SystemC model
Conclusion • Efficient • Compared with model purely in hardware domain • Expressive • Suitable for a wide range of architectures • Declarative • Can be automated through the use of descrition languages • Productive • Clean separation of peration/hardware layer