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11th IEEE Real Time and Embedded Technology and Applications Symposium (RTAS'05)
Improving WCET by Optimizing Worst-Case Paths
San Francisco, CA
March 07-March 10
ISBN: 0-7695-2302-1
Wankang Zhao, Florida State University, Tallahassee, FL
William Kreahling, Florida State University, Tallahassee, FL
David Whalley, Florida State University, Tallahassee, FL
Christopher Healy, Furman University, Greenville, SC
Frank Mueller, North Carolina State University, Raleigh, NC
It is advantageous to perform compiler optimizations to lower the WCET of a task since tasks with lower WCETs are easier to schedule and more likely to meet their deadlines. Compiler writers in recent years have used profile information to detect the frequently executed paths in a program and there has been much effort to develop compiler optimizations to improve these paths in order to reduce average-case execution time. In this paper we describe our approach to reduce WCET by adapting and applying optimizations designed for frequent paths to the worst-case paths in an application. Our compiler uses feedback from our timing analyzer to detect the WCET paths through a function that will be subject to aggressive optimizations, reflect subsequent effects on the WCET of the paths due to these optimizations, and to also ensure that the worst-case path optimizations actually improve the WCET before committing to a code size increase. We evaluate a number of WC path optimizations and present results showing the decrease in WCET versus the increase in code size.
Citation:
Wankang Zhao, William Kreahling, David Whalley, Christopher Healy, Frank Mueller, "Improving WCET by Optimizing Worst-Case Paths," rtas, pp.138-147, 11th IEEE Real Time and Embedded Technology and Applications Symposium (RTAS'05), 2005
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