WCET 06 - A Framework for Response Times Calculation Of Multiple Correlated Events

A Framework for Response Times Calculation Of Multiple Correlated Events

Simon Schliecker, Matthias Ivers, Jan Staschulat, Rolf Ernst

WORKSHOP ON WORST-CASE EXECUTION TIME (WCET) ANALYSIS 2006 (WCET 06)
Dresden, Germany, July 4, 2006

Abstract

Many approaches to determine the response time of a task have difficulty to model multiple memory accesses with variable access times during the execution. Task level approaches require an a-priori knowledge of memory access times. This must be a constant and thus overestimated value. The scheduling level analysis relies on the determined execution times to derive response times, and must account for the possible parallelism when one task is waiting for data. Finally, the worst case total time of multiple accesses is a neglected field of system level analysis.

We present a novel approach to determine the access times of multiple memory accesses of a task efficiently and and far less conservative than previous approaches. The memory accesses may be disturbed by other events in the system. We show how to integrate such a multiple event busy time analysis to take into account behavior of tasks that voluntarily suspend themselves and require multiple data from a remote memory.

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