Master Thesis - Past Projects - Abstract
Evaluation of schedulers using the Enea Advanced Scheduling Framework and improvements of the framework software
Every day new electronics are being introduced into everything we use.
Systems become more and more complex. One category of systems that is
growing rapidly, which builds the foundation of this thesis, are systems
used for safety critical applications. These systems are often built up of
many different processes that share common hardware resources. Examples of
industries that use real-time theory when constructing embedded systems
are car- and phone industries. It is also widely used in airplanes and
medical applications. In many of these types of systems it is not only the
result of a given computation that is important, but also when the result
becomes available. Real-time theory is used to share system resources
among different processes, as well as to help guarantee that the results
from the processes are delivered within their temporal demands.
In order for processes to be able to share resources there has to be some
sort of mechanism that decides which process should get to use a specific
hardware part during what time period, for example get to use the CPU.
Such a mechanism is called a scheduler and one goal of this report is to
evaluate two such schedulers to see if it is possible to create a rule of
thumb when one scheduler is better than the other.
Enea Epact has during the last two years developed a tool, the Enea
Advanced Scheduling Framework (Enea ASF), to aid analysis of the temporal
properties of a system. The tool can collect time measurements from the
target platform automatically to verify and improve the results of the
analysis. This thesis presents the enhancements to this framework made
during the work on evaluating the schedulers, which includes a new
graphical interface and the rewriting of the internal structure.
By using tools like the Enea ASF it is possible to get early indication on
how a system behaves and what type of hardware that is required to run the
system. The ability to get early indications on what type of hardware that
is required in a system, can greatly reduce a project costs. Such a tool
can also pinpoint the areas that are most vital to optimize in order to
minimize hardware costs.
The result from the evaluation of the schedulers is that the EDF scheduler
is much better at preventing deadline misses than the FPS scheduler, but
uses more system resources in doing so. The difference in use of system
resources is not very big though, the EDF scheduler utilizes about
0,008%/process more of the available time between each system tick than
the FPS scheduler. This is partially compensated by the fact that the EDF
scheduler causes less process preemptions.
Keywords: Real-time, Scheduling, RMA, Enea ASF, Embedded system
Author(s): Markus Malmgren
Contact: Jörgen Hansson
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