Everyone got problemz...

1. Time criteriain Real time software design
andits challenges
Vijay Kakani, M.Eng in Computers and communication systems
Department of Electronics and Computer Engineering, University of Limerick
12103004@studentmail.ul.ie

2. Key issues
 Time criteria in real time software design
 Challenges faced by the software designers in the
perspective of time
 Real time worst case scenario examples due to
minor slips in the software design
 Methodologies to overcome time based challenges

3. Time criteriain real time software design
 One among the major deciding factors in real time
software design is time criteria
 A small timely flaw by the designer could cause
most awful damage to the real time system
Example: If a software designer makes a
minute flaw in setting response sensing time
for a timer associated with fire alarm

4. hallenges facedby the designers regarding timely issues
Issue of Parallelism and
synchronization:
Problems regarding this issue occurs in
the
multi-disciplinary environment and
multiple task handlings
Issue of Predictability:
Hurdles concerning this issue rises
purely due to lack of prediction
towards imperative events.

5. Worst case scenarios of real time software
designs
Type of fault : Synchronization fault
Equipment : Digital lung mock up
Key principle : Rate synchronization between medical
device and mock up
Explanation : The equipment synchronizes sampling rate of
medical device(1000 samples/sec) with
mock up rate(100 samples/sec)
Fault : If the designer does a minor slip in scaling of
sampling set frequency and if that is
connected to the patient’s lungs will cause
Contd…

6. Type of fault : Predictability fault
Equipment : 3D mapping software
Key principle : Detecting the frequency of
opponent warheads and designing the 3D
maps
Explanation : The equipment gives the protocols to the
soldiers about the enemy warheads by
detecting the frequencies and predicting 3D map
location
Fault : If the designer does a slight mistake in geo
Worst case scenarios of real time software designs
(contd)

7. Methodologies to overcome
time based challenges
 Mixed model-Round ribon + pre-emptive
priority:
Every task is allocated with deadlines and
prioritization is done accordingly
 Fixed priority- Rate monotonic approach:
RMA- simple logic of setting highest
priority to lowest execution time and vice
versa.
 Dynamic priority- Earliest deadline
first:
EDF- the ready task with earliest
deadline or burst time has highest
priority.
{Synchronization perspective}
Contd...

8. Methodologies to overcome
time based challenges (contd)
{Predictability perspective}
 Generic time band formulations:
These generic formulations
facilitate the designers to predict
very efficiently regarding crucial
issues.
 Cyclic executives:
In this strategy, decisions are made
prior to run time using major and
minor circles/frames. As this
strategy is simple and pre run-time
approach, it handles high
predictability.

9. Acknowledgement
Thanks to the following contributors for
permission in using few diagrams from their
work.
“The Concise Handbook Of Real-Time Systems”,
Time Sys co-operation, version:1.3
Phillip A. Laplante, “Real time system design and analysis”,
3rd Edition, Apr. 2004, 528 pages