Prediction of the Worst Case Execution Time
In real-time systems the tasks are subject to deadlines.
It is essential that the worst-case execution time (WCET) of each task is
known in order to ensure that the system works correctly. The consequences
of a missed deadline range from simply annoying to disastrous -
just imagine a flight control software that does not react in time. It is
the duty of the developer to guarantee that the tasks will always meet the
Computing the worst-case execution time is a challenge:
Simply measuring the execution time of
a task for a given input is typically not safe. It is mostly
impossible to prove that the conditions leading to maximum execution time are
taken into account.
Modern processor components like caches and
pipelines complicate the task of determining the WCET considerably.
For instance, the often safe yet almost never valid assumption of a cache hit
never occurring results in a serious overestimate of the WCET. Overestimates
of the WCET in turn may result in a failure of the overall schedulability
analysis or an overscaled hardware design.
The WCET prediction technology implemented within the
DAEDALUS project is based on statically analyzing a task's intrinsic
cache and pipeline behavior. This allows us to compute correct
and tight upper bounds for the worst-case execution time of
the tasks in an application.
AbsInt Angewandte Informatik GmbH
provides advanced tools and services in the areas of compiler optimization, static
program analysis, and worst-case execution time prediction.