The accuracy of trace-driven simulations of multiprocessors

  • Authors:
  • Stephen R. Goldschmidt;John L. Hennessy

  • Affiliations:
  • Stanford Univ., Stanford, CA;Stanford Univ., Stanford, CA

  • Venue:
  • SIGMETRICS '93 Proceedings of the 1993 ACM SIGMETRICS conference on Measurement and modeling of computer systems
  • Year:
  • 1993

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Abstract

In trace-driven simulation, traces generated for one set of system characteristics are used to simulate a system with different characteristics. However, the execution path of a multiprocessor workload may depend on the order of events occurring on different processing elements. The event order, in turn, depends on system charcteristics such as memory-system latencies and buffer-sizes. Trace-driven simulations of multiprocessor workloads are inaccurate unless the dependencies are eliminated from the traces.We have measured the effects of these inaccuracies by comparing trace-driven simulations to direct simulations of the same workloads. The simulators predicted identical performance only for workloads whose traces were timing-independent. Workloads that used first-come first-served scheduling and/or non-deterministic algorithms produced timing-dependent traces, and simulation of these traces produced inaccurate performance predictions. Two types of performance metrics were particularly affected: those related to synchronization latency and those derived from relatively small numbers of events. To accurately predict such performance metrics, timing-independent traces or direct simulation should be used.