This paper demonstrates CARTS, a compositional analysis tool for real-time systems. We presented an overview of the underlying theoretical foundation and the architecture design of the tool. CARTS is open source and available for free download at http://rtg.cis.upenn.edu/carts/

Chen, Sanjian

Easwaran, Arvind

Lee, Insup

Lee, Jaewoo

Phan, Linh T.X.

Ramaswamy, Vinay

Sokolsky, Oleg

English

Kosmopolis

University of Pennsylvania
ScholarlyCommons
Departmental Papers (CIS) Department of Computer & Information Science
11-2010
CARTS: A Tool for Compositional Analysis of
Real-Time Systems
Linh T.X. Phan
University of Pennsylvania, linhphan@cis.upenn.edu
Jaewoo Lee
University of Pennsylvania, jaewoo@cis.upenn.edu
Arvind Easwaran
University of Pennsylvania, arvinde@cis.upenn.edu
Vinay Ramaswamy
University of Pennsylvania, vinayr@cis.upenn.edu
Sanjian Chen
University of Pennsylvania, sanjian@cis.upenn.edu
See next page for additional authors
Follow this and additional works at: http://repository.upenn.edu/cis_papers
3rd Workshop on Compositional Theory and Technology for Real-Time Embedded Systems (CRTS), San Diego, CA, Nov 2010.
This paper is posted at ScholarlyCommons. http://repository.upenn.edu/cis_papers/459
For more information, please contact libraryrepository@pobox.upenn.edu.
Recommended Citation
Linh T.X. Phan, Jaewoo Lee, Arvind Easwaran, Vinay Ramaswamy, Sanjian Chen, Insup Lee, and Oleg Sokolsky, "CARTS: A Tool for
Compositional Analysis of Real-Time Systems", ACM SIGBED Review 8(1), 62-63. November 2010. http://dx.doi.org/10.1145/
1967021.1967029
CARTS: A Tool for Compositional Analysis of Real-Time Systems
Abstract
This paper demonstrates CARTS, a compositional analysis tool for real-time systems. We presented an
overview of the underlying theoretical foundation and the architecture design of the tool. CARTS is open
source and available for free download at http://rtg.cis.upenn.edu/carts/.
Comments
3rd Workshop on Compositional Theory and Technology for Real-Time Embedded Systems (CRTS), San
Diego, CA, Nov 2010.
Author(s)
Linh T.X. Phan, Jaewoo Lee, Arvind Easwaran, Vinay Ramaswamy, Sanjian Chen, Insup Lee, and Oleg
Sokolsky
This conference paper is available at ScholarlyCommons: http://repository.upenn.edu/cis_papers/459
CARTS: A Tool for Compositional Analysis of
Real-Time Systems
Linh T.X. Phan Jaewoo Lee Arvind Easwaran Vinay Ramaswamy Sanjian Chen Insup Lee Oleg Sokolsky
Department of Computer and Information Sciences, University of Pennsylvania
Email: {linhphan, jaewoo, arvinde, vinayr, sanjian, lee, sokolsky}@cis.upenn.edu
I. INTRODUCTION
As real-time embedded systems are increasingly complex,
integration becomes a great challenge in their design and
development. Managing complexity of the system design is
therefore essential for high-assurance and cost-effective de-
velopment. Component-based design has consequently been
developed and gained its importance over the years as a
powerful technique for complexity management. In this design
paradigm, a large complex system is first decomposed into
smaller and simpler components – which are developed inde-
pendently – before recomposing them into a complete system
using interfaces that abstract away their internal complexities.
To facilitate component-based design, given a component,
one needs to be able to compute the component interface
- an appropriate abstraction of the component’s resource
requirement. This resource interface can be computed either
directly from the component’s workload or by composing the
interfaces of the subcomponents. Accurate and efficient inter-
face generation/composition techniques and tools are therefore
crucial for the component-based design of the system.
To meet the growing needs, we have developed CARTS
(Compositional Analysis of Real-Time Systems) as a platform-
independent tool that automatically generates resource in-
terfaces needed for the compositional analysis of real-time
systems. Our tool is built on top of several existing theoretical
compositional analysis frameworks for real-time systems [2],
[4], [6], [7]. Besides supporting standard schedulers, such as
Rate Monotonic (RM) and Earliest Deadline First (EDF), it
generates both periodic and explicit deadline periodic resource
interfaces. The tool also comes with a friendly GUI and a
rich set of tool features that allow designers to specify and
analyze a wide variety of systems at ease. At the same time,
it is also accompanied by a lightweight command-line option
that enables our tool to be integrated with other existing
toolchains.
II. THEORETICAL FOUNDATION UNDERLYING CARTS
In a hierarchical scheduling framework, the system is par-
titioned into a tree of components that are scheduled in a
hierarchical manner. Each internal node of the tree represents a
composite component, whose children are its sub-components.
Each leaf represents an elementary component, which is a
finite set of tasks in the system.
Figure 1 shows a composite component C made of two
elementary components C1 and C2, which are scheduled under
EDF. Component C1 consists of two tasks T1 and T2, which
C1 C2
T1, T2, T3, T4 : Tasks
 C
RMEDF
T2T1 T3 T4
EDF
R1 R2
R
. . .
Fig. 1. Hierarchical scheduling of a system component.
are scheduled under EDF. Component C2 consists of two tasks
T3 and T4, which are scheduled under RM.
The compositional analysis of the example component C is a
two-step process: (1) compute the resource interface R1 (resp.
R2) of the component C1 (resp. C2) based on the resource de-
mands of the tasks in the component; (2) compute the resource
interface R by composing R1 and R2. The resource interface
R is then composed with the interface of other components to
form the interface of the upper-level component.
Task model (p,e) (p,e,o, j,d) (p,e,x)
Resource model
Periodic (Π,Θ) EDF, RM X RM
EDP (Π,Θ,∆) EDF, RM EDF, RM X
TABLE I
MODELS AND SCHEDULING POLICIES SUPPORTED BY CARTS.
The CARTS core engine runs several algorithms for
computing the interface of any component or a hierarchy of
components that are scheduled under RM or EDF. Table I
summarizes the task models and the scheduling policies for
the components, and their corresponding resource interface
models supported by CARTS. We briefly describe these
models below.
Task models. CARTS supports three different variants of
periodic task models, including: (i) strictly periodic task
with deadline equal to period [7], defined by T = (p,e);
(ii) periodic task with jitter and offset [3], defined by
T = (p,e,o, j,d); and (iii) strictly periodic tasks with resource
sharing [1], defined by T = (p,e,x). Here, p,e,o, j,d,x denote
the period, worst-case execution time, offset, jitter, relative
deadline, and the worst-case execution time of the task in a
critical session, respectively.
Resource interface models. A component interface produced
by CARTS engine can be given as either a periodic or an
explicit deadline periodic resource model. A periodic resource
model [7] is defined by Γ = (Π,Θ) where Π is the period and
Θ is the resource allocation time (0 < Θ ≤ Π). Semantically,
each periodic resource model Γ = (Π,Θ) provides Θ units of
resource in every Π time units. An explicit deadline periodic
(EDP) [2] resource model is characterized by Ω = (Π,Θ,∆)
where Π and Θ are defined as in the periodic resource model,
and ∆ is the explicit deadline (0 < Θ≤ ∆≤Π). Semantically,
EDP is similar to the periodic resource model, except that it
must provide Θ resource units within ∆ time units.
III. THE DESIGN OF CARTS
Figure 2 depicts the different components of the tool and
their interactions. At the back-end, the Scheduling Tree class
contains the reference to the root component of the system.
The Scheduling Algorithms package implements the CARTS
core engine. The XML Interpreter class contains methods for
parsing the XML input file and building Scheduling Tree
instances. Finally, the DBF/SBF Graph Generator class is
responsible for drawing the DBF and SBF of the components
and their interface models. The rest of the components con-
stitute the GUI front-end, which is detailed below.
Scheduling Algorithms DBF/SBF Graph Generator
Scheduling Tree
XML EDITOR
COMPONENT TREE  EDITOR
ANALYSIS OUTPUT
C
A
R
TS
 X
M
L 
In
te
rp
re
te
r
DESIGNER
parse 
XML
generate XML
edit XML save
edit tree
Fig. 2. CARTS system architecture.
Figure 3 shows an overview of the tool GUI. As shown in
the figure, CARTS provides two mechanisms for specifying
a system model: via the Component Tree Editor (the top left
window) or via the XML Editor (the top right window). The
component tree editor is equipped with various features that
enable designers to easily add, modify and remove compo-
nents/tasks in a system, using either the top menu or the
context menu. The XML editor allows an input XML file
description of the system following a simple CARTS XML
template. Further, one can also conveniently convert between
these two descriptions with a click of the convert button.
Depending on the input component task model, one can
apply the different algorithms for generating the component’s
interface (as outlined in Table I) via either the component’s
XML EDITOR
COMPONENT TREE 
EDITOR
ANALYSIS OUTPUT
SBF/DBF
Fig. 3. CARTS graphical user interface.
context menu or the top menu. The computed interface will
then be displayed in the Analysis Output window as an
interface tree, where each node gives the resource interface
of the corresponding component in the input component tree.
The output results can also be saved as an XML file in a similar
format as the input XML description, thereby allowing further
processing and/or interfacing with other tools. Additionally,
the tool also supports visualization of the demand bound
functions of the components and the supply bound functions
of the computed resource interfaces.
IV. CONCLUDING REMARKS
This paper demonstrates CARTS, a compositional analysis
tool for real-time systems. We presented an overview of the
underlying theoretical foundation and the architecture design
of the tool. CARTS is open source and available for free
download at http://rtg.cis.upenn.edu/carts/.
We plan to extend the current CARTS tool to support: (i)
more general task models (e.g., arrival functions [8], tasks with
dependency) and SBF-based resource models (e.g., service
functions [8]); (ii) other common scheduling policies (e.g.,
TDMA, Round Robin); and (iii) multi-mode systems [5].
Finally, we will investigate and incorporate into our toolset
compositional analysis techniques for real-time components
scheduled on multiprocessor platforms such as [6].
REFERENCES
[1] Moris Behnam, Insik Shin, Thomas Nolte, and Mikael Nolin. Sirap:
a synchronization protocol for hierarchical resource sharingin real-time
open systems. In EMSOFT, 2007.
[2] A. Easwaran, M. Anand, and I. Lee. Compositional analysis framework
using edp resource models. In RTSS, 2007.
[3] A. Easwaran, I. Lee, O. Sokolsky, and S. Vestal. A compositional
scheduling framework for digital avionics systems. RTCSA, 2009.
[4] A. Easwaran, I. Shin, O. Sokolsky, and I. Lee. Incremental schedulability
analysis of hierarchical real-time components. In EMSOFT, 2006.
[5] L.T.X. Phan, I. Lee, and O. Sokolsky. Compositional analysis of multi-
mode systems. In ECRTS, 2010.
[6] I. Shin, A. Easwaran, and I. Lee. Hierarchical scheduling framework for
virtual clustering of multiprocessors. In ECRTS, 2008.
[7] I. Shin and I. Lee. Compositional real-time scheduling framework with
periodic model. ACM Trans. Embed. Comput. Syst., 7(3):1–39, 2008.
[8] Ernesto Wandeler and Lothar Thiele. Interface-based design of real-time
systems with hierarchical scheduling. In RTAS, San Jose, USA, 2006.


CARTS: A Tool for Compositional Analysis of Real-Time Systems

ScholarlyCommons@Penn

University of PennsylvaniaScholarlyCommonsDepartmental Papers (CIS) Department of Computer & Information Science11-2010CARTS: A Tool for Compositional Analysis ofReal-Time SystemsLinh T.X. PhanUniversity of Pennsylvania, linhphan@cis.upenn.eduJaewoo LeeUniversity of Pennsylvania, jaewoo@cis.upenn.eduArvind EaswaranUniversity of Pennsylvania, arvinde@cis.upenn.eduVinay RamaswamyUniversity of Pennsylvania, vinayr@cis.upenn.eduSanjian ChenUniversity of Pennsylvania, sanjian@cis.upenn.eduSee next page for additional authorsFollow this and additional works at: http://repository.upenn.edu/cis_papers3rd Workshop on Compositional Theory and Technology for Real-Time Embedded Systems (CRTS), San Diego, CA, Nov 2010.This paper is posted at ScholarlyCommons. http://repository.upenn.edu/cis_papers/459For more information, please contact libraryrepository@pobox.upenn.edu.Recommended CitationLinh T.X. Phan, Jaewoo Lee, Arvind Easwaran, Vinay Ramaswamy, Sanjian Chen, Insup Lee, and Oleg Sokolsky, "CARTS: A Tool forCompositional Analysis of Real-Time Systems", ACM SIGBED Review 8(1), 62-63. November 2010. http://dx.doi.org/10.1145/1967021.1967029CARTS: A Tool for Compositional Analysis of Real-Time SystemsAbstractThis paper demonstrates CARTS, a compositional analysis tool for real-time systems. We presented anoverview of the underlying theoretical foundation and the architecture design of the tool. CARTS is opensource and available for free download at http://rtg.cis.upenn.edu/carts/.Comments3rd Workshop on Compositional Theory and Technology for Real-Time Embedded Systems (CRTS), SanDiego, CA, Nov 2010.Author(s)Linh T.X. Phan, Jaewoo Lee, Arvind Easwaran, Vinay Ramaswamy, Sanjian Chen, Insup Lee, and OlegSokolskyThis conference paper is available at ScholarlyCommons: http://repository.upenn.edu/cis_papers/459CARTS: A Tool for Compositional Analysis ofReal-Time SystemsLinh T.X. Phan Jaewoo Lee Arvind Easwaran Vinay Ramaswamy Sanjian Chen Insup Lee Oleg SokolskyDepartment of Computer and Information Sciences, University of PennsylvaniaEmail: {linhphan, jaewoo, arvinde, vinayr, sanjian, lee, sokolsky}@cis.upenn.eduI. INTRODUCTIONAs real-time embedded systems are increasingly complex,integration becomes a great challenge in their design anddevelopment. Managing complexity of the system design istherefore essential for high-assurance and cost-effective de-velopment. Component-based design has consequently beendeveloped and gained its importance over the years as apowerful technique for complexity management. In this designparadigm, a large complex system is first decomposed intosmaller and simpler components – which are developed inde-pendently – before recomposing them into a complete systemusing interfaces that abstract away their internal complexities.To facilitate component-based design, given a component,one needs to be able to compute the component interface- an appropriate abstraction of the component’s resourcerequirement. This resource interface can be computed eitherdirectly from the component’s workload or by composing theinterfaces of the subcomponents. Accurate and efficient inter-face generation/composition techniques and tools are thereforecrucial for the component-based design of the system.To meet the growing needs, we have developed CARTS(Compositional Analysis of Real-Time Systems) as a platform-independent tool that automatically generates resource in-terfaces needed for the compositional analysis of real-timesystems. Our tool is built on top of several existing theoreticalcompositional analysis frameworks for real-time systems [2],[4], [6], [7]. Besides supporting standard schedulers, such asRate Monotonic (RM) and Earliest Deadline First (EDF), itgenerates both periodic and explicit deadline periodic resourceinterfaces. The tool also comes with a friendly GUI and arich set of tool features that allow designers to specify andanalyze a wide variety of systems at ease. At the same time,it is also accompanied by a lightweight command-line optionthat enables our tool to be integrated with other existingtoolchains.II. THEORETICAL FOUNDATION UNDERLYING CARTSIn a hierarchical scheduling framework, the system is par-titioned into a tree of components that are scheduled in ahierarchical manner. Each internal node of the tree represents acomposite component, whose children are its sub-components.Each leaf represents an elementary component, which is afinite set of tasks in the system.Figure 1 shows a composite component C made of twoelementary components C1 and C2, which are scheduled underEDF. Component C1 consists of two tasks T1 and T2, whichC1 C2T1, T2, T3, T4 : Tasks CRMEDFT2T1 T3 T4EDFR1 R2R. . .Fig. 1. Hierarchical scheduling of a system component.are scheduled under EDF. Component C2 consists of two tasksT3 and T4, which are scheduled under RM.The compositional analysis of the example componentC is atwo-step process: (1) compute the resource interface R1 (resp.R2) of the component C1 (resp. C2) based on the resource de-mands of the tasks in the component; (2) compute the resourceinterface R by composing R1 and R2. The resource interfaceR is then composed with the interface of other components toform the interface of the upper-level component.Task model (p,e) (p,e,o, j,d) (p,e,x)Resource modelPeriodic (Π,Θ) EDF, RM X RMEDP (Π,Θ,∆) EDF, RM EDF, RM XTABLE IMODELS AND SCHEDULING POLICIES SUPPORTED BY CARTS.The CARTS core engine runs several algorithms forcomputing the interface of any component or a hierarchy ofcomponents that are scheduled under RM or EDF. Table Isummarizes the task models and the scheduling policies forthe components, and their corresponding resource interfacemodels supported by CARTS. We briefly describe thesemodels below.Task models. CARTS supports three different variants ofperiodic task models, including: (i) strictly periodic taskwith deadline equal to period [7], defined by T = (p,e);(ii) periodic task with jitter and offset [3], defined byT = (p,e,o, j,d); and (iii) strictly periodic tasks with resourcesharing [1], defined by T = (p,e,x). Here, p,e,o, j,d,x denotethe period, worst-case execution time, offset, jitter, relativedeadline, and the worst-case execution time of the task in acritical session, respectively.Resource interface models. A component interface producedby CARTS engine can be given as either a periodic or anexplicit deadline periodic resource model. A periodic resourcemodel [7] is defined by Γ= (Π,Θ) where Π is the period andΘ is the resource allocation time (0 < Θ ≤ Π). Semantically,each periodic resource model Γ= (Π,Θ) provides Θ units ofresource in every Π time units. An explicit deadline periodic(EDP) [2] resource model is characterized by Ω = (Π,Θ,∆)where Π and Θ are defined as in the periodic resource model,and ∆ is the explicit deadline (0 <Θ≤ ∆≤Π). Semantically,EDP is similar to the periodic resource model, except that itmust provide Θ resource units within ∆ time units.III. THE DESIGN OF CARTSFigure 2 depicts the different components of the tool andtheir interactions. At the back-end, the Scheduling Tree classcontains the reference to the root component of the system.The Scheduling Algorithms package implements the CARTScore engine. The XML Interpreter class contains methods forparsing the XML input file and building Scheduling Treeinstances. Finally, the DBF/SBF Graph Generator class isresponsible for drawing the DBF and SBF of the componentsand their interface models. The rest of the components con-stitute the GUI front-end, which is detailed below.Scheduling Algorithms DBF/SBF Graph GeneratorScheduling TreeXML EDITORCOMPONENT TREE  EDITORANALYSIS OUTPUTCARTS XML InterpreterDESIGNERparse XMLgenerate XMLedit XML saveedit treeFig. 2. CARTS system architecture.Figure 3 shows an overview of the tool GUI. As shown inthe figure, CARTS provides two mechanisms for specifyinga system model: via the Component Tree Editor (the top leftwindow) or via the XML Editor (the top right window). Thecomponent tree editor is equipped with various features thatenable designers to easily add, modify and remove compo-nents/tasks in a system, using either the top menu or thecontext menu. The XML editor allows an input XML filedescription of the system following a simple CARTS XMLtemplate. Further, one can also conveniently convert betweenthese two descriptions with a click of the convert button.Depending on the input component task model, one canapply the different algorithms for generating the component’sinterface (as outlined in Table I) via either the component’sXML EDITORCOMPONENT TREE EDITORANALYSIS OUTPUTSBF/DBFFig. 3. CARTS graphical user interface.context menu or the top menu. The computed interface willthen be displayed in the Analysis Output window as aninterface tree, where each node gives the resource interfaceof the corresponding component in the input component tree.The output results can also be saved as an XML file in a similarformat as the input XML description, thereby allowing furtherprocessing and/or interfacing with other tools. Additionally,the tool also supports visualization of the demand boundfunctions of the components and the supply bound functionsof the computed resource interfaces.IV. CONCLUDING REMARKSThis paper demonstrates CARTS, a compositional analysistool for real-time systems. We presented an overview of theunderlying theoretical foundation and the architecture designof the tool. CARTS is open source and available for freedownload at http://rtg.cis.upenn.edu/carts/.We plan to extend the current CARTS tool to support: (i)more general task models (e.g., arrival functions [8], tasks withdependency) and SBF-based resource models (e.g., servicefunctions [8]); (ii) other common scheduling policies (e.g.,TDMA, Round Robin); and (iii) multi-mode systems [5].Finally, we will investigate and incorporate into our toolsetcompositional analysis techniques for real-time componentsscheduled on multiprocessor platforms such as [6].REFERENCES[1] Moris Behnam, Insik Shin, Thomas Nolte, and Mikael Nolin. Sirap:a synchronization protocol for hierarchical resource sharingin real-timeopen systems. In EMSOFT, 2007.[2] A. Easwaran, M. Anand, and I. Lee. Compositional analysis frameworkusing edp resource models. In RTSS, 2007.[3] A. Easwaran, I. Lee, O. Sokolsky, and S. Vestal. A compositionalscheduling framework for digital avionics systems. RTCSA, 2009.[4] A. Easwaran, I. Shin, O. Sokolsky, and I. Lee. Incremental schedulabilityanalysis of hierarchical real-time components. In EMSOFT, 2006.[5] L.T.X. Phan, I. Lee, and O. Sokolsky. Compositional analysis of multi-mode systems. In ECRTS, 2010.[6] I. Shin, A. Easwaran, and I. Lee. Hierarchical scheduling framework forvirtual clustering of multiprocessors. In ECRTS, 2008.[7] I. Shin and I. Lee. Compositional real-time scheduling framework withperiodic model. ACM Trans. Embed. Comput. Syst., 7(3):1–39, 2008.[8] Ernesto Wandeler and Lothar Thiele. Interface-based design of real-timesystems with hierarchical scheduling. In RTAS, San Jose, USA, 2006.

https://repository.upenn.edu/cgi/viewcontent.cgi?article=1496&amp;context=cis_papers

CARTS: A Tool for Compositional Analysis of Real-Time Systems

Abstract

Similar works

Full text

Available Versions

Kosmopolis

ScholarlyCommons@Penn