A Framework to Quantify the Overestimations of Static WCET Analysis

To reduce complexity while computing an upper bound on the worst-case execution time, static WCET analysis performs over-approximations. This feeds the general feeling that static WCET estimations can be far above the real WCET. This feeling is strengthened when these estimations are compared to measured execution times: generally, it is very unlikely to capture the worstcase from observations, then the difference between the highest watermark and the proven WCET upper bound might be considerable. In this paper, we introduce a framework to quantify the possible overestimation on WCET upper bounds obtained by static analysis. The objective is to derive a lower bound on the WCET to complement the upper bound.

[1]  Clément Ballabriga,et al.  Improving the First-Miss Computation in Set-Associative Instruction Caches , 2008, 2008 Euromicro Conference on Real-Time Systems.

[2]  Christian Ferdinand.  A fast and efficient cache persistence analysis , 2005 .

[3]  Per Stenström,et al.  Timing anomalies in dynamically scheduled microprocessors , 1999, Proceedings 20th IEEE Real-Time Systems Symposium (Cat. No.99CB37054).

[4]  Sharad Malik,et al.  Efficient microarchitecture modeling and path analysis for real-time software , 1995, Proceedings 16th IEEE Real-Time Systems Symposium.

[5]  Pascal Sainrat,et al.  A Context-Parameterized Model for Static Analysis of Execution Times , 2009, Trans. High Perform. Embed. Archit. Compil..

[6]  Isabelle Puaut,et al.  Worst Case Execution Time Analysis for a Processor with Branch Prediction , 2004, Real-Time Systems.

[7]  Pascal Sainrat,et al.  Inter-task WCET computation for a-way instruction caches , 2008, 2008 International Symposium on Industrial Embedded Systems.

[8]  Alan Burns,et al.  A survey of hard real-time scheduling for multiprocessor systems , 2011, CSUR.

[9]  Guillem Bernat,et al.  WCET TOOL CHALLENGE 2008: REPORT , 2008 .

[10]  Jan Gustafsson,et al.  WCET 2008 - Report from the Tool Challenge 2008 -- 8th Intl. Workshop on Worst-Case Execution Time (WCET) Analysis , 2008, WCET.

[11]  F. Cazorla,et al.  20th International Workshop on Worst-Case Execution Time Analysis , 2010 .

[12]  Ting Chen,et al.  Efficient detection and exploitation of infeasible paths for software timing analysis , 2006, 2006 43rd ACM/IEEE Design Automation Conference.

[13]  Reinhard Wilhelm,et al.  Applying Compiler Techniques to Cache Behavior Prediction , 2007 .

[14]  Reinhard Wilhelm,et al.  On Predicting Data Cache Behavior for Real-Time Systems , 1998, LCTES.

[15]  Miodrag Potkonjak,et al.  MediaBench: a tool for evaluating and synthesizing multimedia and communications systems , 1997, Proceedings of 30th Annual International Symposium on Microarchitecture.

[16]  Pascal Sainrat,et al.  OTAWA: An Open Toolbox for Adaptive WCET Analysis , 2010, SEUS.