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other_imulators [11/12/2017 13:15] (actual)
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 +====== Other Simulators ======
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 +There are two main types of performance simulators for processors: trace driven and execution driven. Trace driven simulators use traces obtained from the real execution of programs to drive a performance model while execution driven simulators simulate the actual execution of a program recording detailed performance statistics. The current trend in performance simulation is to use execution driven simulation because it allows much more precise results specially for current processors which exploit instruction level parallelism using out of order execution and speculation.
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 +There are several popular execution driven performance simulators and simulation frameworks like SimOS , MASE, Winsconsin Wind Tunnel II, SimpleScalar,​ Simics, Asim or RSIM.
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 +Some of those simulators, like Simics or SimpleScalar,​ already have functional Linux/x86 ports. However, none of them is suitable for our purposes due to the lack of detail of the simulation and the different system architectures that they model.
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 +Simics is a full system functional simulator which attempts to strike a balance between accuracy and performance. The goal of Simics is to allow the simulation of realistic workloads running unmodified operating systems and applications. Simics supports several simulated architectures including x86, UltraSPARC-II,​ PowerPC and others. It includes accurate device models to simulate I/O intensive applications common in commercial workloads. However, the big performance that it needs and its genericity prevents a detailed enough simulation necessary for many of our tasks.
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 +SimpleScalar is a simulation toolset which provides an infrastructure for simulation and architectural modeling. The toolset can model a variety of platforms ranging from simple unpipelined processors to detailed dynamically scheduled microarchitectures with multiple-level memory systems. However, it simulates only uniprocessor systems.
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 +RSIM has been used by many research groups since its publication and continues to be used nowadays. However, up to our knowledge, no one has published a functional x86 port until now. The original RSIM authors reported initial efforts in this direction, but their x86 port was never published, if it was ever completed.
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 +Schaelicke and Parker ML-RSIM is a derivative of URSIM which is based on the original RSIM. It models the entire Input/​Output subsystem and includes a functional operative system kernel called Lamix which is System V compatible. ML-RSIM has been ported to Linux/x86 architectures.
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 +Unfortunately,​ ML-RSIM differs significantly from RSIM and does not model a cc-NUMA architecture,​ which makes it unfit for our research.