Resource monitors: A design methodology for operating systems

Resource manager objects are the operating system entities that manage computer system resources. In this paper we extend Hoare's and Brinch Hansen's monitor concept, and introduce a resource monitor language construct that represents a resource manager object. Resource monitors provide requesting processes with implicit synchronization, and do not require separate processes to perform the resource access operations. The resource monitor construct is compared to current language constructs used to structure operating system software. For this purpose we use an evaluation methodology that combines software complexity measurements with program performance measurements. The evaluation itself is carried out in a Concurrent Pascal-like programming environment. The current language constructs have a software complexity that is larger by 37 to 219 per cent over the resource monitor's complexity. The run-time synchronization overhead of programs that use current language constructs is 1.43 to 2.75 times higher than the overhead of programs that use a resource monitor.     

A study of several metrics for programming effort

As the cost of programming becomes a major component of the cost of computer systems, it becomes imperative that program development and maintenance be better managed. One measurement a manager could use is programming complexity. Such a measure can be very useful if the manager is confident that the higher the complexity measure is for a programming project, the more effort it takes to complete the project and perhaps to maintain it. Until recently most measures of complexity were based only on intuition and experience. In the past 3 years two objective metrics have been introduced, McCabe's cyclomatic number v(G) and Halstead's effort measure E. This paper reports an empirical study designed to compare these two metrics with a classic size measure, lines of code. A fourth metric based on a model of programming is introduced and shown to be better than the previously known metrics for some experimental data.     

Process vs resource‐oriented Petri net modeling of automated manufacturing systems

Since the 1980s, Petri nets (PN) have been widely used to model automated manufacturing systems (AMS) for analysis, performance evaluation, simulation, and control. They are mostly based on process‐oriented modeling methods and thus termed as process‐oriented PN (POPN) in this paper. The recent study of deadlock avoidance problems in AMS led to another type of PN called resource‐oriented PN (ROPN). This paper, for the first time, compares these two modeling methods and resultant models in terms of modeling power, model complexity for analysis and control, and some critical properties. POPN models the part production processes straightforwardly, while ROPN is more compact and effective for deadlock resolution. The relations between these two models are investigated. Several examples are used to illustrate them. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

操作系统电源管理研究进展

系统级动态电源管理技术的关键问题是在系统性能与能耗之间进行权衡.在硬件提供支持的基础上,操作系统电源管理的优势在于操作系统作为系统资源管理者,根据工作负载和硬件资源电源状态的特征,在满足系统性能约束条件下作出电源管理决策和控制,降低系统能耗.从优化控制策略和操作系统资源管理的角度,综述操作系统电源管理研究现状及其关键技术.对两类动态电源管理策略进行详细分析,讨论了从资源管理角度进行操作系统电源管理的研究思路和问题,对当前面临的主要问题和发展趋势进行了总结和展望.     

SADDLE: A computer-aided structural analysis and dynamic design language—part II. database management system

The SADDLE program is a tool for computer-aided optimal design of structural and mechanical systems. The system is divided into four parts; the pre-processor, the “analyzer”, the “synthesizer” and the post-processor. The structural model and the design data are generated by the preprocessor. The analyzer used the finite-element method to compute deflections and stresses in the structure. The synthesizer solves the design problem that is cast into a nonlinear programming format. The post-processor is used to examine the analysis and design results. Different parts of the system interact via a global database. The database management system is presented in detail, in this part of a two part paper. The data manager has three distinct parts: the data model processor, the resource manager and the I/O manager. Both the relational and hierarchical data models are supported. Tuning parameters are provided to enhance computational efficiency on different computers. The emphasis is on friendlier user-system interaction; free-format input, error recoveries, and easy means to create, edit, and update information.     

面向SoC设计的网格PSE资源管理器与原型实现

集成电路技术的发展始终存在着两个主要矛盾：集成电路工艺加工能力的快速增长与设计生产力的矛盾,集成电路复杂度增加与设计时间紧缩的矛盾。文章从网格技术的角度,把SoC设计过程中不同的设计资源,包括IP核、EDA设计工具软件、代码、设计专家信息等,通过统一的资源管理机制实现对各种设计资源的管理,解决SoC设计对资源共享和协同的需要,提高SoC设计的整体效率。同时介绍了面向SoC设计网格问题求解环境下资源管理器的原型实现。     

Models,metrics, and management of IS development

Two types of models can assist the information system manager in gaining greater insight into the system development process. They are: isomorphic models that represent cause-effect relationships between certain conditions (e.g., structured techniques) and certain observable states (e.g., productivity change); and paramorphic models that describe an outcome but do not describe the processes or variables that influence the outcome (e.g., estimation of project time or cost). The two models are shown to be interrelated since the relationships of the first model are determinants of the parameters of the second model.IS managers can make significant contributions by developing isomorphic models tailored to their own organizations. However, metrics that measure relevant characteristics of programs and systems are required before substantial progress can be made. Although some initial attempts have been made to develop metris for program quality, program complexity, and programmer skill, much more work remains to be done. In addition, other metries must be developed that will require the involvement of personnel, not only in the computer sciences, but also in information systems, the behavioral sciences, and IS management.     

集中式集群资源调度框架的可扩展性优化

集中式集群资源管理系统既能够确保全局资源状态的一致性亦拥有多种调度模型,因此被广泛应用于实际系统中.但是,当集中式资源管理器在接收并处理大规模的周期性心跳信息时,由于其采用单一节点来维护全局资源状态,所以资源管理器的负载压力急剧增加,导致调度能力降低,影响了集群系统的可扩展性.针对上述问题,提出一种"没有变化就不更新"...     

A resource management and fault tolerance services in grid computing

In grid computing, resource management and fault tolerance services are important issues. The availability of the selected resources for job execution is a primary factor that determines the computing performance. In this paper, we propose a resource manager for optimal resource selection. Our resource manager automatically selects the set of optimal resources among candidate resources that achieves optimal performance using a genetic algorithm. Typically, the probability of a failure is higher in the grid computing than in a traditional parallel computing and the failure of resources affects job execution fatally. Therefore, a fault tolerance service is essential in computational grids. And grid services are often expected to meet some minimum levels of Quality of Service (QoS) for a desirable operation. To address this issue, we also propose a fault tolerance service that satisfies QoS requirements. We extend the definition of failures from the conventional notion of failures in distribute systems in order to provide a fault tolerance service that deals with various types of resource failures, which include process failures, processor failures, and network failures. We also design and implement a fault detector and a fault manager. The implementation and simulation results indicate that our approaches are promising in that (1) the resource manager finds the optimal set of resources that guarantees efficient job execution, (2) the fault detector detects the occurrence of resource failures and (3) the fault manager guarantees that the submitted jobs complete and the performance of job execution is improved due to job migration even if some failures occur.     

Measuring complexity in structured vs unstructured cobol programs

Measuring programmer productivity and estimating programming time and costs are among the most worrisome and persistent problems facing the programming manager. A key element in both problem areas is program complexity. It has been demonstrated in practice that a measure of program complexity is an indispensable aid in evaluating a programming effort. The purpose of this paper is to present a prototype for a composite measure of program complexity. The paper presents a basis for a technique upon which an objective quantitative evaluation for any program or programming effort could be made.This index of complexity would give the manager a tool for a quantitative assessment of programming efforts so that judgments about the relative merits of programs and programmers can be based on objective data and an objective measure. The measure is applied against a reference group of COBOL programs, several of which were written in a structured programming environment. The index of complexity and the data from which it is derived are used to evaluate the complexity of structured vs unstructured COBOL programming styles.     

A simulation sequencing algorithm

In the course of developing a programming project for a course in operating systems, a general purpose language (Burroughs B6700 Algol) possessing concurrency and semaphores was used to provide a process oriented simulation sequencing facility. This facility has been used successfully to simulate several simple operating systems. The facility comprises three procedures along with ‘simulation semaphore’ variables. The first procedure, when called, inserts a simulated time delay into the progress of a simulation model process: the latter two procedures provide a P and a V operation on simulation semaphores, and are used to synchronize processes in a simulation model. The P operation may insert a simulated time delay into the progress of a process. These procedures are explained and presented along with a simple example to show their use.     

Complexity measure evaluation and selection

A formal model of program complexity developed earlier by the authors is used to derive evaluation criteria for program complexity measures. This is then used to determine which measures are appropriate within a particular application domain. A set of rules for determining feasible measures for a particular application domain are given, and an evaluation model for choosing among alternative feasible measures is presented. This model is used to select measures from the classification trees produced by the empirically guided software development environment of R.W. Selby and A.A. Porter, and early experiments show it to be an effective process     

Subsystems of Processes with Deadlock Avoidance

A graph-oriented approach to deadlock avoidance, which treates both shared and exclusive locking, has been described [6]. The method is particularly suited for database systems. With enhancements introduced here, the problem of indefimite delay, i.e., the possibility that a process will not run to completion (will be delayed indefinitely) can be eliminated. The approach taken is to partition the resource system into subsystems, each of which can be scheduled independently. Indefinite delay is avoided by the construction of subsystems that guarantee the completion of a process or the granting of a resource request. Further, we show how the subsystem approach can be applied systematically so as to approximate FIFO scheduling of resource requests, while avoiding deadlock and indefmite delay. Other scheduling disciplines can also be realized. A lock manager program utilizing the FIFO method has been implemented.     

PGSW-OS: a novel approach for resource management in a semantic web operating system based on a P2P grid architecture

A web operating system is an operating system that users can access from any hardware at any location. A peer-to-peer (P2P) grid uses P2P communication for resource management and communication between nodes in a grid and manages resources locally in each cluster, and this provides a proper architecture for a web operating system. Use of semantic technology in web operating systems is an emerging field that improves the management and discovery of resources and services. In this paper, we propose PGSW-OS (P2P grid semantic Web OS), a model based on a P2P grid architecture and semantic technology to improve resource management in a web operating system through resource discovery with the aid of semantic features. Our approach integrates distributed hash tables (DHTs) and semantic overlay networks to enable semantic-based resource management by advertising resources in the DHT based upon their annotations to enable semantic-based resource matchmaking. Our model includes ontologies and virtual organizations. Our technique decreases the computational complexity of searching in a web operating system environment. We perform a simulation study using the Gridsim simulator, and our experiments show that our model provides enhanced utilization of resources, better search expressiveness, scalability, and precision.     

基于Petri网结构的多处理机实时操作系统

多处理机环境下的实时系统具有并发事件驱动性质,其软件结构展现了多重同步点以及生产者与消费者之间的关系,这导致了复杂的控制结构.对于此类系统软件的开发缺少标准的方法和工具,造成了软件低效、程序结构不清晰、开发成本高、维护困难的现象的出现.根据Petri网易于描述并行/并发现象的特点,采用它来解决多处理机软件的描述问题,介绍了一种以Petri网图形方式在多处理机系统环境下进行程序设计的方法.该方法基于两种程序设计级别:任务级和作业级.前者负责描述基本操作,由单一控制线程完成;后者用于并行/并发程序建模,由整个多处理机系统来执行.在作业级程序设计中,用户采用面向对象Petri网来描述并行程序结构,以建立系统模型.该方法以一种接近于程序员的思维方式去设计并发软件,提供了一种可靠的并行结构的程序.阐述了支持此种程序设计方法的操作系统结构及其实现原理.     

Software project management using PROMPT: A hybrid metrics, modeling and utility framework

In this paper, we present a ‘forward-looking’ decision support framework that integrates up-to-date metrics data with simulation models of the software development process in order to support the software project management control function. This forward-looking approach (called the PROMPT method) provides predictions of project performance and the impact of various management decisions. Tradeoffs among performance measures are accomplished using outcome based control limits (OBCLs) and are augmented using multi-criteria utility functions and financial measures of performance to evaluate various process alternatives. The decision support framework enables the program manager to plan, manage and track current software development activities in the short term and to take corrective action as necessary to bring the project back on track. The model provides insight on potential performance impacts of the proposed corrective actions. A real world example utilizing a software process simulation model is presented.     

在操作系统中实现处理机进程和存储进程的分离

通过为进程分配和回收处理机资源和存储器资源，传统操作系统实施对处理机和存储器的管理和控制，在多处理机操作系统中，当处理机和存储器之间的互连方式比较复杂时，仅仅构造唯一一种进程抽象，不能很好地实施对处理机资源和存储器资源的管理，基于以上思想，在操作系统中应该构造两类进程抽象；处理机进程和存储进程，并实现处理机进程和存储进程的分离，首先分析了构造两类进程抽象（处理机进程和存储进程）并实现二者分离的原因，根据分析提出了实现处理进程和存储进程分离的方法。     

Complexity measures for rule-based programs

Software complexity measures are quantitative estimates of the amount of effort required by a programmer to comprehend a piece of code. Many measures have been designed for standard procedural languages, but little work has been done to apply software complexity concepts to nontraditional programming paradigms. This paper presents a collection of software complexity measures that were specifically designed to quantify the conceptual complexity of rule-based programs. These measures are divided into two classes: bulk measures, which estimate complexity by examining aspects of program size, and rule measures, which gauge complexity based on the ways in which program rules interact with data and other rules. A pilot study was conducted to assess the effectiveness of these measures. Several measures were found to correlate well with the study participants' ratings of program difficulty and the time required by them to answer questions that required comprehension of program elements. The physical order of program rules was also shown to affect comprehension. The authors conclude that the development of software complexity measures for particular programming paradigms may lead to better tools for managing program development and predicting maintenance effort in nontraditional programming environments