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MAST
Modeling
and
Analysis
Suite for Real-Time Applications
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Table of Contents
MAST 1.3.7.8 is now available. This
version introduces basic support for the following new modelling
elements:
- add the RT_EP network driver
- add the "message_partitioning"
attribute
- add the RTA_Overhead_Model attribute
However, we still need to change the
schedulability analysis tools to take into account these new model
elements. This will be released in version 1.3.8.
A "beta" version of a graphical editor for MAST models is also
provided with this version (gmasteditor). This version is still under
development. We expect version 1.3.8 of
MAST to provide a stable version of this tool.
Version 1.3.7 introduced the new xml input format, with conversion
programs from the original text format to xml and bak. Three XML
schemas are created to describe MAST elements:
- Mast_Model.xsd : described the
format of a MAST model
- Mast_Result.xsd: describes the
format of the results of a MAST analysis tool
- Mast_Trace.xsd: describes the
format of a trace results file coming out from the Mast_Sim simulator.
Version 1.3.6 introduced the hierarchical schedulers in the real-time
model. It does so by separating from the old "processing_resource"
model the concept of the primary scheduler, and by defining another
object, the secondary scheduler, which van run on any desired scheduler
through a scheduling server. See the mast model documentation for
additional information.
This version also introduced earliest deadline first (EDF) schedulers
and the stack resource protocol (SRP) synchronization policy for shared
objects.
Several new analysis tools are introduced:
- EDF_Monoprocessor_Analysis: For
single processor systems with and EDF scheduler (also supporting fixed
priority interrupts)
- EDF_Within_Priorities_Analysis: For
systems with a fixed priority primary scheduler and one or more EDF
secondary schedulers
- Deadline Assignment: For EDF tasks,
it assigns the scheduling deadlines equal to the deadlines specified as
timing requirements, and assigns the task preemption levels according
to the correrct order (by deadline minus release jitter in reverse
order)
Introduction
MAST is an open source set of tools that
enables
modeling real-time applications and performing timing analysis of those
applications. The MAST model can be used in a UML design environment to
design real-time applications, representing all the real-time
behavior
and requirements together with the design information, and allowing an
automatic schedulability analysis. Please visit MAST-UML
for additional information on this topic.
MAST is still under development. The
MAST
analysis tools are listed below, with a "*"
marking those that are not yet available:
- Worst-case response time
schedulability analysis (RTA):
- Offset Based RTA for fixed
priorities
- Holistic RTA for fixed priorities
- Offset-Based Optimized RTA for
fixed
priorities
- Classic Rate Monotonic RTA for
fixed
priorities
- Varying Priorities RTA
- EDF Monoprocessor RTA
- EDF-Within-Priorities RTA, for
hierarchical scheduling
- *Multiple
Event
- Calculation of blocking times
- Single processor
- Remote blockings for
multi-processor
- Assignment of optimum priority
ceilings and preemption levels
- Calculation of Slack Times
- Transaction Slacks
- System Slacks
- Processing Resource Slacks
- Operation Slacks
- Optimized Priority Assignment
Techniques
- Single-processor
- HOPA
- Simulated Annealing
An Event-driven simulation tool is
available for version 1.2.2 of MAST from the SIM-MAST page.
The new features that can be found in MAST
are the following:
- A very rich model of the real time
system
is used. It is an event-driven model in which complex dependence
patterns
among the different tasks can be established. For example, tasks may be
activated with the arrival of several events, or may generate several
events
at their output. This makes it ideal for analyzing real-time systems
that
have been designed using UML or similar design tools, which have
event-driven
models of the system. The current version only supports linear
distributed
systems, but support for multiple-event systems will be available very
soon.
- The latest offset-based analysis
techniques
are used to enhance the results of the analysis. These techniques are
much
less pessimistic than previous schedulability analysis techniques for
distributed
systems.
- The toolset is open source and
fully
extensible.
That means that other teams may provide enhancements. This contains a
full support for fixed priority systems, and limited support for EDF
scheduling (only supported for single processor. Distributed EDF as
well as mixed scheduled systems and other dynamically scheduled systems
will be added in the future.
- The tools support the analysis of
both
hard and soft timing requirements, respectively through the response
time analysis tools, and the event-driven simulation tool.
Documents
The following documents describing the
MAST
environment are available:
- Getting
Started:
- MAST
Object
Hierarchy:
A listing of all
the objects currently supported in the MAST real-time system model (mast-hierarchy.html)
- MAST
Description:
The MAST format for describing models
of real-time applications, with a few examples (mast_description.pdf)
- MAST
Analysis Techniques:
- MAST
Example
Results:
A description of the results of the
examples
available in the MAST distribution (mast-examples.html)
- MAST Tool
Restrictions
This document
describes
the restrictions that must be observed for using the MAST tools (mast-restrictions.pdf)
- README
- MAST
status
A text
document
describing the current development status of MAST
- MAST-UML
Describes the MAST
UML methodology and toolset
- MAST XML
schemas
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