Tracing tools are used widely to help analyze, design, and tune both hardware and software systems. This paper describes a tool called Shade which combines efficient instruction-set simulation with a flexible, extensible trace generation capability. Efficiency is achieved by dynamically compiling and caching code to simulate and trace the application program. The user may control the extent of tracing in a variety of ways; arbitrarily detailed application state information may be collected during the simulation, but tracing less translates directly into greater efficiency. Current Shade implementations run on SPARC systems and simulate the SPARC (Versions 8 and 9) and MIPS I instruction sets. This paper describes the capabilities, design, implementation, and performance of Shade, and discusses instruction set emulation in general.

This paper discusses Nimrod, a tool for performing parametised simulations over networks of loosely coupled workstations. Using Nimrod the user interactively generates a parametised experiment. Nimrod then controls the distribution of jobs to machines and the collection of results. A simple graphical user interface which is built for each application allows the user to view the simulation in terms of their problem domain. The current version of Nimrod is implemented above OSF DCE and runs on DEC Alpha and IBM RS6000 workstations (including a 22 node SP2). Two different case studies are discussed as an illustration of the utility of the system. 1 INTRODUCTION A wide range of scientific and engineering experiments can be solved using numeric simulation. Examples include finite element analysis, computational fluid dynamics, electromagnetic and electronic simulation, pollution transport, granular flow and digital logic simulation. Accordingly, some very large codes have been written over ...

Interactive program steering permits researchers to monitor and guide their applications during runtime. Interactive steering can help make end users more effective in addressing the scientific or engineering questions being solved with these programs, and it may be used to improve the performance of complex parallel and distributed codes. Progress is a toolkit for developing steerable applications. Users instrument their applications with library calls and then steer parallel applications with Progress' runtime system. Progress provides steerable objects which encapsulate program abstractions for monitoring and steering during program execution. Once created, steering objects are known to and manipulated by Progress' two components: (1) a server executing in the same memory space as the target program and capable of inspecting and manipulating program state, and (2) a potentially remote client providing command and graphical interfaces. Developers instrument their applications with t...

(to appear in Software-Practice and Experience) A signi cant amount of software development isevolutionary, involving the modi cation of already existing programs. To a large extent, the modi ed programs produce the same results as the original program. This similarity between the original program and the development program is utilized by relative debugging. Relative debugging is a new concept that enables the user to compare the execution of two programs by specifying the expected correspondences between their states. A relative debugger concurrently executes the programs, veri es the correspondences, and reports any di erences found. We describe our novel debugger, called Guard, and its relative debugging capabilities. Guard is implemented by using our library of debugging routines, called Dynascope, which provides debugging primitives in heterogeneous networked environments. To demonstrate the capacity of Guard for debugging in heterogeneous environments, we describe an experiment in which the execution of two programs is compared across Internet. The programs are written in di erent programming languages and executing on di erent computing platforms.

This paper presents a library of directing commands which enable the construction of powerful directors. The interface has been implemented in a Unix environment as a runtime subsystem running in the directed program's address space. The paper provides the description of the interface and the basic programming techniques in building directors. Examples of novel applications, illustrating the use of the directing interface, are demonstrated by the directors for the visualization of program control and structured snapshots

In this paper we describe our experience applying the concepts of reflection to a legacy transaction processing (TP) monitor in order to support the implementation of extended transaction models. In the past ten years, numerous extended transaction models have been proposed to address the challenges posed by new advanced applications. Few practical implementations of these extended transaction models exist and none are being used in a commercial TP monitor. We believe the reason for this state of affairs is that the interface and functionality of commercial TP monitors is "locked in" to a fixed transaction model. We have developed the Reflective Transaction Framework as a practical method to implement extended transaction models on a commercial TP monitor. The design of our framework is based on the principles of computational reflection, and in particular open implementation.

steering lets researchers investigate, calibrate, and control long-running, resource-intensive applications at runtime. Magellan, a prototype computational steering system, uses ACSL to intelligently control multithreaded, asynchronous steering servers that cooperatively steer applications.

Introspection or the ability to observe one's own behavior is one of the most powerful capabilities of human intelligence; it is the basis for understanding and improvement of one's behavior and of human progress. Similarly, introspective computer systems, introduced in this thesis, examine, reason about, and change their own behavior in powerful new ways. Because the complexity of computers is rapidly increasing, yet is restricted by limited human resources, the most attractive quality of introspective computers is their ability to manage this growing complexity themselves. Self-managing computer systems would greatly expand the rational power and complexity of computer systems that can be successfully built. The main difficulty in constructing introspective computer systems is enabling the system to obtain a description of its complete behavior in a dynamic and unobtrusive way. This thesis proposes the partition of the system into two threads of control. The first thread performs the...

cdb is a simple, source-level debugger for ANSI C programs compiled by lcc, a retargetable C compiler. cdb is completely independent of its target architecture. This independence is achieved by embedding a small amount of itself --- a `nub' --- in the program to be debugged and by having the compiler emit machine-independent symbol-table data and related code. This paper describes the design of a nub interface for debugging, a target-independent implementation of this interface for cdb, and the implementation of cdb itself. When compared to platform-specific debuggers, cdb's implementation is minuscule: the nub, debugger, and associated communications routines take about 1500 lines of C, and fewer than 600 lines were added to lcc's front end to emit symbol tables and breakpoint hooks. All this code is machine independent. Introduction Source-level debuggers are notoriously machine-dependent programs. Most debuggers depend not only on the machine on which they run, but also depend...

The significance of software systems has rapidly increased. The assurance of software systems has become a critical requirement of the information age. Formal verification on the design of a system and testing on a system implementation with a variety of inputs has been used for this purpose. However, verifying a design can not guarantee the correctness of an implementation. Although testing is performed on implementation, it does not give formal guarantees because it is not possible to test exhaustively. Run-time formal analysis is proposed to combat the weaknesses of formal verification and testing. Run-time formal analysis aims to assure the correctness of the current execution at run-time. Run-time formal analysis is performed based on a formal specification of system requirements. This dissertation proposes a framework for run-time formal analysis. We investigate general issues for the framework. We show that a set of the properties run-time formal analysis can detect is a subset...