FUNCTIONAL SIZE MEASUREMENT FOR PROCESSOR LOAD ESTIMATION IN AUTOSAR
Hassan Soubra, Alain Abran, Mehdi Sehit
Agenda Introduction
Research Issue
Litterature review
Overviews of COSMIC, AUTOSAR and SYMTA/S
Experimental Set-up
Results
Conclusions
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Introduction
• Software functional size is a key input for building software development estimation models, effort models, benchmark models, and quality models
• It can also be used for purposes such as processor load estimation, network traffic estimation and acceptance condition estimation
• Context: Autosar
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Litterature review
COSMIC based guideline and procedure for
AUTOSAR
Prediction and verification of
timing constraints of
embedded software
Procedure and tool for
Simulink
Basic timing model to allow application of such timing interfaces
Procedure and tool for UML
Code Size Optimizing
memory requirements respects real-
time schedulability
constraints
Load balancing mechanisms for efficient utilization of
CPU
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Overviews of COSMIC, AUTOSAR and SYMTA/S
COSMIC
measures the Func@onal User Requirements (FUR) of soGware. Func@onal size measured by COSMIC is
designed to be independent of any implementa@on
decisions embedded in the opera@onal ar@facts of the
soGware.
AUTOSAR
provides a set of concepts and a methodology for
design and implementa@on of automo@ve E/E systems. AUTOSAR methodology follows a model-‐driven
approach
SYMTA/S
Models and analyzes real-‐@me embedded systems in order to measure system performance (e.g. Worst
Case Execu@on @me -‐WCET, CPU load, end to end
latencies, etc.) while taking into account various
scheduling constraints and differing execu@on scenarios.
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Overviews of COSMIC, AUTOSAR and SYMTA/S
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Experimental Set-up
Architecture Number of ECUs in the architecture
Total Number of AUTOSAR models used in
the architecture
Total Number of Runnables used in the
architecture
A 1 107 107B 2 12 24C 3 5 15D 4 21 84E 5 7 35F 6 11 66G 7 1 7Total number used in all
architectures 164 338
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Approach
We used linear regression analysis to build es@ma@on models of ECU processor load for AUTOSAR models.
Correlate the rela@on between ECU processor load and COSMIC func@onal size ()
from steps 1 &2
Observe the processor load
In the AUTOSAR model developed using SYMTA/S, run from 0% (free) to 100% (fully occupied).
Measure the func@onal size of an input AUTOSAR model
AGer its alloca@on to one of the seven architectures. To speed up the measurement process and reduce the possibility of human error, we used an automated prototype tool developed in our study.
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Automation Tool
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Automation Tool
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Results
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Linear regression to estimate processor load
The mean difference between the actual data and the es@mated data for the 24 models is 10.59 %. The accuracy of the es@mates is approximately 90%.
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Conclusion
• A study of the relationship between FSM and processor load, in AUTOSAR.
• The findings have demonstrated the dependence of ECU processor load on COSMIC functional size.
• Automation prototype tool. • 24 models were used to verify the accuracy of the
estimates produced by our automated approach.
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