Real-Time Execution Monitoring

Today's programming methodology emphasizes the study of static aspects of programs. In practice, however, monitoring a program in execution, i.e., monitoring a process, is routinely done by any programmer whose task it is to produce a reliable piece of software. There are two reasons why one might want to examine the dynamic aspects of a program: first, to evaluate the performance of a program, and hence to assess its overall behavior; and second, to demonstrate the presence of programming errors, isolate erroneous program code, and correct it. This latter task is commonly called ``debugging a program' and requires a detailed insight into the innards of a program being executed. Today, many computer systems are being used to measure and control real-world processes. The pace of execution of these systems and their control programs is therefore bound to timing constraints imposed by the real-world process. As a step towards solving the problems associated with execution monitoring of real-time programs, we develop a set of appropriate concepts and define the basic requirements for a real-time monitoring facility. As a test case for the theoretical treatment of the topic, we design hardware and software for an experimental real-time monitoring system and describe its implementation.     

总线上的实时非干预可再现故障注入模式

研究总结了总线上的实时非干预可再现同步故障注入模式，并给出了它的具体实现。研究基础是针对目前国内应用比较广泛的以Intel8086／80186、386EX、5l系列兼容单片机为MPU／MCU的高可靠目标系统，是该类目标系统软件实时仿真测试环境的一个重要组成部分。测试过程将不影响目标系统的实时性能和功能，并可实现测试过程的行为再现。它的实现利用了现代微机的高性能、多任务多线程以及FPGA、PCI等技术。作为故障注入模式的一种，其具有新颖性和重要的实用价值。     

Replay and testing for concurrent programs

Attention is given to the problems that arise during the testing and debugging cycle of concurrent programs because of their nondeterministic execution behavior, whereby multiple executions of a concurrent program with the same input may exercise different synchronization sequences and even produce different results. These problems are solved by using deterministic execution debugging and testing. The purpose of deterministic execution debugging to to replay executions of a concurrent program so that debugging information can be collected. Examples of semaphores and monitors are used to illustrate the approach and the process of designing replay tubes is described. The use of regression testing to see if earlier debugging and testing introduced new errors, is examined     

Tracing and recording interrupts in embedded software

During the system development, developers often must correct wrong behavior in the software—an activity colloquially called program debugging. Debugging is a complex activity, especially in real-time embedded systems because such systems interact with the physical world and make heavy use of interrupts for timing and driving I/O devices.Debugging interrupts is difficult, because they cause non-linear control flow in programs which is hard to reproduce in software. Record/replay mechanisms have proven their use to debugging embedded systems, because they provide means to recreate control flows offline where they can be debugged.In this work, we present the data tracing part of the record/replay mechanism that is specifically targeted to record interrupt behavior. To tune our tracing mechanism, we use the observed principle of return address clustering and a formal model for quantitative reasoning about the tracing mechanism. The presented heuristic and mechanisms show surprisingly good results—with higher fingerprint widths an 800 percent speedup on the selector function and a 300 percent reduction on duplicates for non-optimal selector functions—considering the leanness of the approach. Using an equal portion for the fingerprint and for the return address lead to the best results in our experiments.     

Monitoring and debugging distributed realtime programs

In this paper we describe the design and implementation of an integrated monitoring and debugging system for a distributed real-time computer system. The monitor provides continuous, transparent monitoring capabilities throughout a real-time system's lifecycle with bounded, minimal, predictable interference by using software support. The monitor is flexible enough to observe both high-level events that are operating system- and application-specific, as well as low-level events such as shared variable references. We present a novel approach to monitoring shared variable references that provides transparent monitoring with low overhead. The monitor is designed to support tasks such as debugging realtime applications, aiding real-time task scheduling, and measuring system performance. Since debugging distributed real-time applications is particularly difficult, we describe how the monitor can be used to debug distributed and parallel applications by deterministic execution replay.     

SPiDER—An advanced symbolic debugger for Fortran 90/HPF programs

Debuggers play an important role in developing parallel applications. They are used to control the state of many processes, to present distributed information in a concise and clear way, to observe the execution behavior, and to detect and locate programming errors. More sophisticated debugging systems also try to improve understanding of global execution behavior and intricate details of a program. In this paper we describe the design and implementation of SPiDER, which is an interactive source‐level debugging system for both regular and irregular High‐Performance Fortran (HPF) programs. SPiDER combines a base debugging system for message‐passing programs with a high‐level debugger that interfaces with an HPF compiler. SPiDER, in addition to conventional debugging functionality, allows a single process of a parallel program to be expected or the entire program to be examined from a global point of view. A sophisticated visualization system has been developed and included in SPiDER to visualize data distributions, data‐to‐processor mapping relationships, and array values. SPiDER enables a programmer to dynamically change data distributions as well as array values. For arrays whose distribution can change during program execution, an animated replay displays the distribution sequence together with the associated source code location. Array values can be stored at individual execution points and compared against each other to examine execution behavior (e.g. convergence behavior of a numerical algorithm). Finally, SPiDER also offers limited support to evaluate the performance of parallel programs through a graphical load diagram. SPiDER has been fully implemented and is currently being used for the development of various real‐world applications. Several experiments are presented that demonstrate the usefulness of SPiDER. Copyright © 2002 John Wiley & Sons, Ltd.     

基于组态软件与VB的实时监控系统

介绍了一种过程控制实验装置，它是一个基于PLC、组态软件和VB的两容液位实时监控系统。选用电动调节阀和交流变频器作为执行机构，提供了两种控制手段；采用PLC开发下位机程序，控制执行机构输出；采用组态王开发上位机画面，对PLC进行实时监控；并且实现了VB与组态王之间的通信，为编写高级算法提供了平台。给出了系统的硬件组成、软件设计及VB与组态王之间的通信方法。此系统基表满足了高校中过程控制实验的需要。     

Software monitoring through formal specification animation

This paper presents a formal specification-based software monitoring approach that can dynamically and continuously monitor the behaviors of a target system and explicitly recognize undesirable behaviors in the implementation with respect to its formal specification. The key idea of our approach is in building a monitoring module that connects a specification animator with a program debugger. The requirements information about expected dynamic behaviors of the target system are gathered from the formal specification animator, while the actual behaviors of concrete implementations of the target system are obtained through the program debugger. Based on the information obtained from both sides, the judgement on the conformance of the concrete implementation with respect to the formal specification is made timely while the target system is running. Furthermore, the proposed formal specification-based software monitoring technique does not embed any instrumentation codes to the target system nor does it annotate the target system with any formal specifications. It can detect implementation errors in a real-time manner, and help the developers and users of the system to react to the problems before critical failure occurs.     

A Hardware Memory Race Recorder for Deterministic Replay

As hardware vendors transition to multicore chips, software vendors face increased software reliability challenges. To effectively debug software in this new world, developers must be able to replay executions that exhibit a bug so that they can zero in on concurrency bugs - especially intermittent ones. Such deterministic replay also aids fault detection and recovery, intrusion detection, and the like. Deterministic replay requires both a recorder and a replayer. The recorder logs information during multithreaded program execution that is sufficient to enable deterministic replay. In the postmortem analysis, the replayer uses the logged information, together with the program binary, to faithfully replay the original execution. The replay will always exercise the same bugs and produce the same outputs. Clearly, an investment in modest chip resources has great potential to ease the challenges of debugging the multithreaded software that both users and vendors will continue to demand     

Verification of concurrent control flow in distributed computer systems

An approach to verifying control flow in distributed computer systems (DCS) is presented. The approach is based on control flow checking among software components distributed over processors and cooperating among them. In this approach, control-flow behavior of DCS software is modeled and contained in special software components called verifiers. The verifiers are distributed over the processors and consulted to check the correctness of the control flow in DCS software during its execution. Algorithms for deriving the verifiers are presented. This technique can detect global errors including synchronization errors as well as local errors. It can be used for sequential or concurrent software at various levels of details. Experiments show that using this technique requires no significant overhead.<>     

Meet real-time requirements of parallel programs and maximallyutilize system resources

The time-cost behavior of a program directly depends on its execution environment (i.e., the number of other programs in the system). We present techniques to analyze the time-cost behavior of programs that include the effect of their execution environment. It is assumed the underlying system has a shared memory architecture. The paper shows that one can analytically relate a parallel program's time cost to its execution environment. A direct benefit of the work is to let us meet the real-time requirement of a parallel program and utilize maximally a multiprocessor system's resource     

Reactive process control using a blackboard architecture

A software architecture to engineer complex process control applications must combine into the same paradigm efficient reactive and real-time functionalities and mechanisms to capture dynamic time-pressured intelligent behaviors, and must provide convenient high level tools to free the programmer from having to think at an unappropriate level of detail. We implement such characteristics into a blackboard framework that builds the basic abstract elements of reactive behavior and the blackboard computational model on top of low level real-time operating system functions. Under this approach, the engineer gets a powerful and flexible high level medium to map a complex system design that requires artificial intelligence techniques, like intelligent monitoring, and reactive planning and execution, with fully support for real-time programming. The paper also reviews other alternatives which have been explored in the past recent years for implementing complex reactive planning and execution systems.     

A taxonomy and catalog of runtime software-fault monitoring tools

A goal of runtime software-fault monitoring is to observe software behavior to determine whether it complies with its intended behavior. Monitoring allows one to analyze and recover from detected faults, providing additional defense against catastrophic failure. Although runtime monitoring has been in use for over 30 years, there is renewed interest in its application to fault detection and recovery, largely because of the increasing complexity and ubiquitous nature of software systems. We present taxonomy that developers and researchers can use to analyze and differentiate recent developments in runtime software fault-monitoring approaches. The taxonomy categorizes the various runtime monitoring research by classifying the elements that are considered essential for building a monitoring system, i.e., the specification language used to define properties; the monitoring mechanism that oversees the program's execution; and the event handler that captures and communicates monitoring results. After describing the taxonomy, the paper presents the classification of the software-fault monitoring systems described in the literature.     

一种高速列车ATP目标模拟器的设计与实现

针对高速列车ATP的测试需求,开发出了ATP目标模拟器.对ATP目标模拟器的原理和硬件设计思路进行了介绍,重点叙述了通过脚本实现自动测试的软件设计方案.对目标模拟器的软件架构,脚本执行程序、信号控制程序及两者之间数据交互的实现方法进行了详细说明.该目标模拟器已经投入使用,运行情况良好,已成为试验室ATP系统集成验证测试的必备工具.     

Admission control for a responsive distributed middleware using decision trees to model run-time parameters

The software in modern systems has become too complex to make accurate predictions about their performance under different configurations. Real-time or even responsiveness requirements cannot be met because it is not possible to perform admission control for new or changing tasks if we cannot tell how their execution affects the other tasks already running. Previously, we proposed a resource-allocation middleware that manages the execution of tasks in a complex distributed system with real-time requirements. The middleware behavior can be modeled depending on the configuration of the tasks running, so that the performance of any given configuration can be calculated. This makes it possible to have admission control in such a system, but the model requires knowledge of run-time parameters. We propose the utilization of machine-learning algorithms to obtain the model parameters, and be able to predict the system performance under any configuration, so that we can provide a full admission control mechanism for complex software systems. In this paper, we present such an admission control mechanism, we measure its accuracy in estimating the parameters of the model, and we evaluate its performance to determine its suitability for a real-time or responsive system.     

基于LabVIEW的汽车网络监控系统研究

使用LabVIEW作为监控系统开发软件,实现对使用SAE J1939协议的汽车网络监控.整套系统由上位机、汽车网络监控软件和USB-CAN总线适配器构成.监控系统可实现对车载网络中CAN报文的监听显示,模拟节点向车载网络发送报文;提供应用程序接口,实现监控数据在汽车网络中的直接读写,并以图形化方式显示数据;使用数据库存储数据,实现数据回放.监控系统在全顺电动车研发中得到了应用,效果良好.     

Behavioral profiles—a way to model and validate program behavior

Software architecture contains, in addition to its structural part, interaction patterns that can be regarded as part of the architectural solution of the system. The interaction patterns define architecturally significant behavior of the software system. In this paper we propose a visual modeling language, behavioral profiles, for specifying architecturally significant behavioral rules for an application. The language is built on the Unified Modeling Language (UML), which is a visual language widely used in software development. We show how behavioral profiles can be used to support software designers in creating behavioral models that conform to some predefined rules and for ensuring that an application behaves correctly with respect to the rules given in the profiles. A tool called Bebop was built to support software engineers in behavioral profile‐based design and analysis of program behavior. To evaluate the approach and the tools in different application domains, they are utilized in three cases. The size of the applications used in the cases varies from small to quite large software systems, and from academic to industrial ones. The examples demonstrate how the approach presented can be used in practice for different steps in a software engineering process. The examples cover specializing an application framework and monitoring the program execution in run‐time. In addition, they show how behavioral profiles can be used to support guided program comprehension and to validate program execution by analyzing execution traces. Copyright © 2010 John Wiley & Sons, Ltd.     

An Approach to Concurrent Control Flow Checking

A control flow checking scheme capable of detecting control flow errors of programs resulting from software coding errors, hardware malfunctions, or memory mutilation during the execution of the program is presented. In this approach, the program is partitioned into loop-free intervals and a database containing the path information in each of the loop-free intervals is derived from the detailed design. The path in each loop-free interval actually traversed at run time is recorded and then checked against the information provided in the database, and any discrepancy indicates an error. This approach is general, and can detect all uncompensated illegal branches. Any uncompensated error that occurs during the execution of a loop-free interval and manifests itself as a wrong branch within the loop-free interval or right after the completion of execution of the loop-free interval is also detectable. The approach can also be used to check the control flow in the testing phase of program development. The capabilities, limitations, implementation, and the overhead of using this approach are discussed.     

An intelligent agent with layered architecture for operating systems resource management

Abstract: A software agent is defined as an autonomous software entity that is able to interact with its environment. Such an agent is able to respond to other agents and/or its environment to some degree, and has some sort of control over its internal state and actions. In belief–desire–intention (BDI) theory, an agent's behavior is described in terms of a processing cycle. In this paper, based on BDI theory, the processing cycle is studied with a software feedback mechanism. A software feedback or loop‐back control mechanism can perform functions without direct external intervention. A feedback mechanism can continuously monitor the output of the system under control (the target system), compare the result against preset values (goals of the feedback control) and feed the difference back to adjust the behavior of the target system in a processing cycle. We discuss the modeling and design aspects of an autonomous, adaptive monitoring agent with layered control architecture. The architecture consists of three layers: a scheduling layer, an optimizing layer and a regulating layer. Experimental results show that the monitoring agent developed for an e‐mail server is effective.