A Multilevel I/O Tracer for Timing and Performance Analysis of Storage Systems in IaaS Cloud

REACTION 2014. 3rd International Workshop on Real-time and Distributed Computing in Emerging Applications. Rome, Italy. December 2nd, 2014.Data centers are more and more relying on hybrid storage systems consisting of flash memory based storage devices and traditional hard disk drives. Optimal data placement in such hybrid storage systems is a very important issue in the domain of cloud computing and virtualization. This is specially the case when users need that storage systems enforce Quality of Service requirements on I/Os performed, for example for multimedia applications. To characterize Virtual Machine (VM) I/O workload properties such as timing predictability or throughput, monitor-ing services are necessary on such new architectures. This article presents a multilevel I/O tracer for virtual machines that relies on and complement different state-of-the-art tools. It produces I/O traces at different levels of the Linux I/O software stack. The I/O tracer gives an exhaustive information that allows administrators to precisely characterize virtual machine I/O behavior in terms of percentage of read/write I/Os, percentage of random/sequential, I/O request inter-arrival time, etc. This tool is the first piece towards a middleware whose purpose is to meet user QoS requirements thanks to optimal data placement and migration policies in a hybrid storage system in the context of an IaaS Cloud.This work has been funded by the French government through the National Research Agency (ANR) Investment referenced ANR-A0-AIRT-07Publicad

Real Time Scheduling and its use with Ada

International audienc

About Real Time Scheduling Analysis of Ada Applications

International audienc

Modeling and verification of memory architectures with AADL and REAL

Real-Time Embedded systems must respect a wide range of non-functional properties, including safety, respect of deadlines, power or memory consumption. We note that correct hardware resource dimensioning requires taking into account the impact of the whole software, both the user code and the underlying runtime environment. AADL allows one to precisely capture all of them. In this article, we evaluate the AADL modeling to define memory architectures, and then verification rules to assess that the memory is correctly dimensioned. We use the REAL domain-specific language to express memory requirements (such as layout or size) and then validate them on a case-study using the VxWorks real-time kernel

Implementing an AADL performance analyzer

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Performance Analysis of an Assembly System: a Case Study

International audiencePetri nets are well suited for modelling production systems and analysis of their performance. In this paper we study a flowshop system driven by a set of local command units and a central controller, modelled with Timed Coloured Petri nets by means of CPN Tools. We show that Petri nets can be applied not only to improve its production rate by comparing various algorithms for the controller policy service, but also to analyse the significance of parameters as conveying and mechanical delays, maximum work-in-process or to understand problems appeared in the real syste

Scheduling Analysis from Architectural Models of Embedded Multi-Processor Systems

International audienceAs embedded systems need more and more computing power, many products require hardware platforms based on multiple processors. In case of real-time constrained systems, the use of scheduling analysis tools is mandatory to validate the design choices, and to better use the processing capacity of the system. To this end, this paper presents the extension of the scheduling analysis tool Cheddar to deal with multi-processor schedul- ing. In a Model Driven Engineering approach, useful infor- mation about the scheduling of the application is extracted from a model expressed with an architectural language called AADL. We also define how the AADL model must be writen to express the standard policies for the multi-processor scheduling

Combined Security and Schedulability Analysis for MILS Real-Time Critical Architectures

Real-time critical systems have to comply with stringent timing constraints, otherwise, disastrous consequences can occur at runtime. A large effort has been made to propose models and tools to verify timing constraints by schedulability analysis at the early stages of system designs. Fewer efforts have been made on verifying the security properties in these systems despite the fact that sinister consequences can also happen if these properties are compromised. In this article, we investigate how to jointly verify security and timing constraints. We show how to model a security architecture (MILS) and how to verify both timing constraints and security properties. Schedulability is investigated by the mean of scheduling analysis methods implemented into the Cheddar scheduling analyzer. Experiments are conducted to show the impact that improving security has on the schedulability analysis

The SMART Project: Multi-Agent Scheduling Simulation of Real-time Architectures

International audienceThe ongoing SMART collaborative project addresses modeling and analysis techniques for software intensive real-time systems. The AADL modeling language has been selected to describe multithread, multi-partition, multi-processor and multi-core architectures. This paper focuses on the use of the Marzhin simulator that is based on a Multi-Agent technology for providing scheduling analysis results of real-time systems. This simulator is integrated in the AADL Inspector product and can also be used to animate realistic 3D animations

Teaching Real-Time Scheduling Analysis with Cheddar

National audienceThis article is a presentation of the Cheddar toolset.Cheddar is a GPL open-source scheduling analysis tool.It has been designed and distributed to allow students to understand the main concepts of the real-time scheduling theory.The tool is built around a simplified ADL (Architecture Description Language)devoted to real-time scheduling theory. Students can directly build their real-time systems models with this ADL andits associated editor, however, it is expected that they use modeling tools to illustrate how scheduling analysis fits in an engineering process.In this article, we introduce the Cheddar ADL and the scheduling analysis features of Cheddar. We alsopresent how Cheddar is implemented and how it can be adapted to specific requirements.Two examples of use of Cheddar are then described.Finally, in the annex of this article, teachers may find a sample of hand-outs that may be used to illustrate real-time scheduling theory with their students