WCET analysis for a Java processor

ABSTRACT

In this paper we propose a solution for a worst-case execution time (WCET) analyzable Java system: a combination of a time predictable Java processor and a tool that performs WCET analysis of Java bytecode. We present a Java processor, called JOP, designed for time-predictable execution of real-time tasks. JOP is an implementation of the Java virtual machine (JVM) in hardware. The execution time of bytecodes, the instructions of the JVM, is known cycle accurate for JOP. Therefore, JOP simplifies the low-level WCET analysis. A method cache, that fills whole Java methods into the cache, is analyzable with respect to the WCET. The WCET analysis tool is based on integer linear programming. The tool performs the low-level analysis at the bytecode level and integrates the method cache analysis for a two block cache.

REFERENCES

• 1: C. Artho and A. Biere. Subroutine inlining and bytecode abstraction to simplify static and dynamic analysis. Electronic Notes in Theoretical Computer Science, 141(1):109--128, December 2005.
• 2: I. Bate , G. Bernat , G. Murphy , P. Puschner, Low-level analysis of a portable Java byte code WCET analysis framework, Proceedings of the Seventh International Conference on Real-Time Systems and Applications (RTCSA'00), p.39, December 12-14, 2000
• 3: G. Bernat, A. Burns, and A. Wellings. Portable worst-case execution time analysis using java byte code. In Proc. 12th EUROMICRO Conference on Real-time Systems, Jun 2000.
• 4: James Gosling , Greg Bollella, The Real-Time Specification for Java, Addison-Wesley Longman Publishing Co., Inc., Boston, MA, 2000
• 5: M. Dahm. Byte code engineering with the BCEL API. Technical report, Freie Universitat Berlin, April 2001.
• 6: DCT. Lightfoot 32-bit Java processor core. data sheet, September 2001.
• 7: Sujit Dey , Debashis Panigrahi , Li Chen , Clark N. Taylor , Krishna Sekar , Pablo Sanchez, Using a Soft Core in a SoC Design: Experiences with picoJava, IEEE Design & Test, v.17 n.3, p.60-71, July 2000 [doi>10.1109/54.867896]
• 8: Jiri Gaisler, A Portable and Fault-Tolerant Microprocessor Based on the SPARC V8 Architecture, Proceedings of the 2002 International Conference on Dependable Systems and Networks, p.409-415, June 23-26, 2002
• 9: T. R. Halfhill. Imsys hedges bets on Java. Microprocessor Report, August 2000.
• 10: Real-Time Objects on the Bare Metal: An Efficient Hardware Realization of the JavaTM Virtual Machine, Proceedings of the Fourth International Symposium on Object-Oriented Real-Time Distributed Computing, p.53, May 02-04, 2001
• 11: Imsys. Im1101c (the cjip) technical reference manual/v0.25, 2004.
• 12: J. Kreuzinger, U. Brinkschulte, M. Pfeffer, S. Uhrig, and T. Ungerer. Real-time event-handling and scheduling on a multithreaded Java microcontroller. Microprocessors and Microsystems, 27(1):19--31, 2003.
• 13: Yau-Tsun Steven Li , Sharad Malik, Performance analysis of embedded software using implicit path enumeration, Proceedings of the ACM SIGPLAN 1995 workshop on Languages, compilers, & tools for real-time systems, p.88-98, November 1995, La Jolla, California, United States
• 14: Y.-T. S. Li , S. Malik , A. Wolfe, Efficient microarchitecture modeling and path analysis for real-time software, Proceedings of the 16th IEEE Real-Time Systems Symposium (RTSS '95), p.298, December 05-07, 1995
• 15: Tim Lindholm , Frank Yellin, Java Virtual Machine Specification, Addison-Wesley Longman Publishing Co., Inc., Boston, MA, 1999
• 16: Thomas Lundqvist , Per Stenström, Timing Anomalies in Dynamically Scheduled Microprocessors, Proceedings of the 20th IEEE Real-Time Systems Symposium, p.12, December 01-03, 1999
• 17: J. Michael O'Connor , Marc Tremblay, picoJava-I: The Java Virtual Machine in Hardware, IEEE Micro, v.17 n.2, p.45-53, March 1997 [doi>10.1109/40.592314]
• 18: Peter Puschner , Guillem Bernat, WCET Analysis of Reusable Portable Code, Proceedings of the 13th Euromicro Conference on Real-Time Systems, p.45, June 13-15, 2001
• 19: Peter Puschner , Alan Burns, Guest Editorial: A Review of Worst-Case Execution-TimeAnalysis, Real-Time Systems, v.18 n.2-3, p.115-128, May 2000 [doi>10.1023/A:1008119029962]
• 20: Peter Puschner , Alan Burns, Writing Temporally Predictable Code, Proceedings of the The Seventh IEEE International Workshop on Object-Oriented Real-Time Dependable Systems (WORDS 2002), p.85, January 07-09, 2002
• 21: P. Puschner , Ch. Koza, Calculating the maximum, execution time of real-time programs, Real-Time Systems, v.1 n.2, p.159-176, Sep. 1989 [doi>10.1007/BF00571421]
• 22: Peter P. Puschner , Anton V. Schedl, Computing Maximum Task Execution Times — A Graph-BasedApproach, Real-Time Systems, v.13 n.1, p.67-91, July 1997 [doi>10.1023/A:1007905003094]
• 23: M. Schoeberl. A time predictable instruction cache for a Java processor. In On the Move to Meaningful Internet Systems 2004: Workshop on Java Technologies for Real-Time and Embedded Systems (JTRES 2004), volume 3292 of LNCS, pages 371--382, Agia Napa, Cyprus, October 2004. Springer.
• 24: M. Schoeberl. Evaluation of a Java processor. In Tagungsband Austrochip 2005, pages 127--134, Vienna, Austria, October 2005.
• 25: M. Schoeberl. JOP: A Java Optimized Processor for Embedded Real-Time Systems. PhD thesis, Vienna University of Technology, 2005.
• 26: Martin Schoeberl, Real-Time Garbage Collection for Java, Proceedings of the Ninth IEEE International Symposium on Object and Component-Oriented Real-Time Distributed Computing (ISORC'06), p.424-432, April 24-26, 2006 [doi>10.1109/ISORC.2006.66]
• 27: Martin Schoeberl, A time predictable Java processor, Proceedings of the conference on Design, automation and test in Europe: Proceedings, March 06-10, 2006, Munich, Germany
• 28: A. C. Shaw, Reasoning About Time in Higher-Level Language Software, IEEE Transactions on Software Engineering, v.15 n.7, p.875-889, July 1989 [doi>10.1109/32.29487]

INDEX TERMS

Primary Classification:
  D. Software
  D.3 PROGRAMMING LANGUAGES
      D.3.4 Processors

Keywords:
java processor, real-time system, worst-case execution time