A SYSTEM FOR VISUALIZING AND DEBUGGING DISTRIBUTED REAL-TIME SYSTEMS WITH MONITORING SUPPORT

1996 ◽  
Vol 06 (03) ◽  
pp. 355-400
Author(s):  
JEFFREY J.P. TSAI ◽  
YAO-DONG BI ◽  
STEVE J.H. YANG
Keyword(s):  
Real Time ◽  
Interaction Graph ◽  
Real Time Systems ◽  
Timing Behavior ◽  
Timing Constraint ◽  
Execution Traces ◽  
Target Program ◽  
Run Time ◽  
Time Systems ◽  
Process Interaction

Based on system execution traces, this paper presents a dynamic approach for visualizing and debugging timing constraint violations occurring in distributed real-time systems. The system execution traces used for visualization and debugging are collected during the execution of a target program in such a way that its run-time behavior is not interfered with. This is made possible by our non-interference distributed real-time monitoring system which is capable of collecting system’s run-time traces by monitoring and fetching the data passing through the internal buses of a target system. After the run-time data has been collected, the visualization and debugging activities then proceeded. The timing behavior of a target program is visualized as two graphs—the Colored Process Interaction Graph (CPIG) and the Dedicated Colored Process Interaction Graph (DCPIG). The CPIG depicts the timing behavior of a target program by graphically representing interprocess relationships during their communication and synchronization. The DCPIG can reduce visualization and debugging complexity by focusing on the portion of a target program which has direct or indirect correspondence with an imposed timing constraint. With the help of the CPIG and the DCPIG, a timing analysis method is used for computing the system-related timing statistics and analyzing the causes of timing constraint violations. A visualization and debugging system, called VDS, has been implemented using OpenWindows on Sun-4’s/UNIX workstations.

A Method for Simultaneously Satisfying Important Constraints and Dependencies for Many Different Types of Processes in Embedded Real-Time Systems

2011 ◽  
Author(s):  
Jia Xu
Keyword(s):  
Real Time ◽  
Computation Time ◽  
Real Time Systems ◽  
Worst Case ◽  
Release Times ◽  
Different Types ◽  
High Assurance ◽  
Run Time ◽  
Soft Deadline ◽  
Time Systems

In most embedded, real-time applications, processes need to satisfy various important constraints and dependencies, such as release times, offsets, precedence relations, and exclusion relations. Embedded, real-time systems with high assurance requirements often must execute many different types of processes with such constraints and dependencies. Some of the processes may be periodic and some of them may be asynchronous. Some of the processes may have hard deadlines and some of them may have soft deadlines. For some of the processes, especially the hard real-time processes, complete knowledge about their characteristics can and must be acquired before run-time. For other processes, prior knowledge of their worst case computation time and their data requirements may not be available. It is important for many embedded real-time systems to be able to simultaneously satisfy as many important constraints and dependencies as possible for as many different types of processes as possible. In this paper, we discuss what types of important constraints and dependencies can be satisfied among what types of processes. We also present a method which guarantees that, for every process, no matter whether it is periodic or asynchronous, and no matter whether it has a hard deadline or a soft deadline, as long as the characteristics of that process are known before run-time, then that process will be guaranteed to be completed before predetermined time limits, while simultaneously satisfying many important constraints and dependencies with other processes.

scholarly journals Problem Detection in Real-Time Systems by Trace Analysis

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Mathieu Côté ◽  
Michel R. Dagenais
Keyword(s):  
Real Time ◽  
Critical Path ◽  
Test Cases ◽  
Real Time Systems ◽  
Scheduling Problems ◽  
New Approach ◽  
Execution Traces ◽  
Problem Detection ◽  
Execution Model ◽  
Time Systems

This paper focuses on the analysis of execution traces for real-time systems. Kernel tracing can provide useful information, without having to instrument the applications studied. However, the generated traces are often very large. The challenge is to retrieve only relevant data in order to find quickly complex or erratic real-time problems. We propose a new approach to help finding those problems. First, we provide a way to define the execution model of real-time tasks with the optional suggestions of a pattern discovery algorithm. Then, we show the resulting real-time jobs in a Comparison View, to highlight those that are problematic. Once some jobs that present irregularities are selected, different analyses are executed on the corresponding trace segments instead of the whole trace. This allows saving huge amount of time and execute more complex analyses. Our main contribution is to combine the critical path analysis with the scheduling information to detect scheduling problems. The efficiency of the proposed method is demonstrated with two test cases, where problems that were difficult to identify were found in a few minutes.

Feasible Automatic Reconfigurations of Real-Time OS Tasks

2012 ◽  
pp. 390-414 ◽  
Author(s):  
Hamza Gharsellaoui ◽  
Atef Gharbi ◽  
Mohamed Khalgui ◽  
Samir Ben Ahmed
Keyword(s):  
Real Time ◽  
User Requirements ◽  
Real Time Systems ◽  
Temporal Parameters ◽  
Temporal Properties ◽  
Run Time ◽  
Time Systems

This research deals with reconfigurable uniprocessor embedded real-time systems to be implemented by different OS tasks that should be independent, synchronous, and periodic, and that should meet functional and temporal properties described in user requirements. The authors define two forms of automatic reconfigurations assumed to be applied at run-time: addition-removal of tasks or just modifications of their temporal parameters; WCET and/or periods. The authors define a new semantic of reconfigurations where a crucial criterion to consider is the automatic improvement of the system’s feasibility at run-time.

Run-Time Guarantees for Real-Time Systems—The USES Approach

1999 ◽  
pp. 410-419 ◽  
Author(s):  
Christian Ferdinand ◽  
Daniel Kästner ◽  
Marc Langenbach ◽  
Florian Martin ◽  
Michael Schmidt ◽  
...  
Keyword(s):  
Real Time ◽  
Real Time Systems ◽  
Run Time ◽  
Time Systems
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