System Performance Analyses of Out-of-Order Superscalar Processors Using Analytical Method

Hak-Jun KIM  Sun-Mo KIM  Sang-Bang CHOI  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E82-A   No.6   pp.927-938
Publication Date: 1999/06/25
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section of Papers Selected from 1998 International Technical Conference on Circuits/Systems, Computers and Communications (ITC-CSCC '98))
superscalar processor,  instruction-level parallelism,  in-order issue,  out-of-order issue,  instruction window,  reorder buffer,  queuing model,  

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This research presents a novel analytic model to predict the instruction execution rate of superscalar processors using the queuing model with finite-buffer size and synchronous operation mode. The proposed model is also able to analyze the performance relationship between cache and pipeline. The proposed model takes into account various kinds of architectural parameters such as instruction-level parallelism, branch probability, the accuracy of branch prediction, cache miss, and etc. To prove the correctness of the model, we performed extensive simulations and compared the results with the analytic model. Simulation results showed that the proposed model can estimate the average execution rate accurately within 10% error in most cases. The proposed model can explain the causes of performance bottleneck which cannot be uncovered by the simulation method only. The model is also able to show the effect of the cache miss on the performance of out-of-order issue superscalar processors, which can provide an valuable information in designing a balanced system.