Robert Francis Berry

AT-SPEED TEST IS NOT NECESSARILY AN AC TEST

In many circles at-speed test is synonymous to AC test. The object of this paper is to root out this misconception. In order to achieve an effective AC test special attention must be paid to the way the patterns are generated. The AC strength is a measure that allows assessing how well a pattern generator can serve in applying AC test vectors to the logic. Generators with high AC strengths tend to perform better than generators with low AC strengths.

Profiling with AspectJ

A system for manufacturing tire molding metal molds with electrical discharge machining is disclosed, which makes possible the rotation, longitudinal and cross feeding of a work table on which a workpiece to be machined into a tire molding metal mold is placed and the rotation, lifting and lowering of a machining head, whereby the workpiece is discharge-machined by feeding a discharge machining electrode in a plurality of different directions corresponding to a plurality of projections protruding essentially vertical to the tire molding surface of the tire molding metal mold to be machined, and by changing electrodes having such profiles as to prevent the excess metal removal of the projections in accordance with each of the electrode feeding directions.

A unifying approach to performance analysis in the Java environment

In general, performance analysis tools deal with large volumes of highly complex data of varying types and at varying levels of granularity. The result is that it is common for there to be many different tools and components that implement performance data collection, recording, and reporting in an analysis environment. This variety complicates communication within a group and makes cross-group communication about specific performance findings even more difficult. The analysis of the performance of JavaTM virtual machines and Java applications introduces additional complexity. We describe an approach that unifies the recording and reporting components of performance analysis into a single data model and standard set of reports. We have employed this model with significant success in the analysis of IBMs Developer Kits for the Java virtual machine.

AC strength of a pattern generator

The AC strength of a pattern generator is the fraction of the exhaustive two-pattern count that it can apply to the logic given sufficient time. It is a measure that allows assessing how well a pattern generator can serve in applying AC test vectors to the logic. Generators with high AC strengths tend to perform better than generators with low AC strengths.Special generators with high AC strengths can be designed with a considerable penalty of hardware overhead. An alternative to designing special pattern generators that can serve well during AC test is to separate the inputs of the logic fed by the generator, so that no two inputs belonging to the same output cone in the logic are connected to adjacent stages of the generator. This input separation will facilitate an effective AC test, and will not suffer from the high overhead that the special generators suffer from.This paper introduces the notion of the AC strength of a pattern generator and proposes the input separation scheme that will allow an efficient AC test to be performed on the logic.

Computer benchmark evaluation and design of experiments: a case study

The author defines installation tuning and promotes it as an important area of concern for computer configurations. Examples include deciding on the paging configuration for a particular workload and partitioning available memory into system and user areas. Available tuning options are often difficult to select due to poor understanding of their effects, so analytic models rarely exist for these areas. The author illustrates the use of various models to assess the significance of installation tuning factors. A case study is presented in which a statistical model for response time is developed incorporating the key factors of user load, paging, and main storage configuration. A case study is presented in which a statistical design of experiments to computer performance analysis is presented. General statistical issues pertaining to the design and analysis of computer performance experiments are identified and illustrated. >

Trends, challenges and opportunities for performance engineering with modern business software

The author looks at trends in software and systems, and the current and likely implications of these trends on the discipline of performance engineering. In particular, he examines software complexity growth and its consequences for performance engineering for enhanced understanding, more efficient analysis and effective performance improvement. The pressures for adaptive and autonomous systems introduce further opportunities for performance innovation. The promise of aspect oriented software development technologies for assisting with some of these challenges is introduced.

CEPBen: A Benchmark for Complex Event Processing Systems

Complex Event processing CEP has emerged over the last ten years. CEP systems are outstanding in processing large amount of data and responding in a timely fashion. While CEP applications are fast growing, performance management in this area has not gain much attention. It is critical to meet the promised level of service for both system designers and users. In this paper, we present a benchmark for complex event processing systems: CEPBen. The CEPBen benchmark is designed to evaluate CEP functional behaviours, i.e., filtering, transformation and event pattern detection and provides a novel methodology of evaluating the performance of CEP systems. A performance study by running the CEPBen on Esper CEP engine is described and discussed. The results obtained from performance tests demonstrate the influences of CEP functional behaviours on the system performance.

Responsive systems: an introduction

This paper introduces responsive systems: systems that are real-time, event-based, or time-dependent. There are a number of trends that are accelerating the adoption of responsive systems: timeliness requirements for business information systems are becoming more prevalent, embedded systems are increasingly integrated into soft real-time command-and-control systems, improved message-oriented middleware is facilitating growth in event-processing applications, and advances in service-oriented and component-based techniques are lowering the costs of developing and deploying responsive applications. The use of responsive systems is illustrated here in two application areas: the defense industry and online gaming. The papers in this special issue of the IBM Systems Journal are then introduced. The paper concludes with a discussion of the key remaining challenges in this area and ideas for further work.

An approach to detecting changes in the factors affecting the performance of computer systems

Resolving intermittent performance problems in computer systems is made easier by pinpointing when a change occurs in the systems perforrnance-determinin g factors (e.g., workload composition, configuration). Since we often lack direct measurements of performance factors, this paper presents a procedure for indirectly detecting such changes by analyzing performance characteristics (e.g., response times, queue lengths). Our procedure employs a widely used clustering algorithm to identify candidate change points (the times at which performance factors change), and a newly developed statistical test (based on an AR(1) time series model) to determine the signficance of candidate change points. We evaluate our procedure by using simulations of M/M/1, FCFS queueing systems and by applying our procedure to measurements of a mainframe computer system at a large telephone company. These evaluations suggest that our procedure is effective in practice, especially for larger sample sizes and smaller utilizations. We further conclude that indirectly detecting changes in performance factors appears to be inherently difficult in that the sensitivity of a detection procedure depends on the magnitude of the change in performance characteristics, which often has a nonlinear relationship with the change in performance factors. Thus, a change in performance factors (e.g., increased service times) may be more readily detected in some situations (e.g., very low or very high utilizations) than in others (e.g., moderate utilizations). A key insight here is that the sensitivity of the detection procedure can be improved by choosing appropriate measures of performance characteristics. For example, our experience and analysis suggest that queue lengths can be more sensitive than response times to changes in arrival rates.

Trigeneration using biomass energy for sustainable development

Purpose: The paper aims to design and prove the concept of micro-industry using trigeneration fuelled by biomass, for sustainable development in rural NW India. Design/methodology/approach: This is being tested at village Malunga, near Jodhpur in Rajasthan. The system components comprise burning of waste biomass for steam generation and its use for power generation, cooling system for fruit ripening and the use of steam for producing distilled water. Site was selected taking into account the local economic and social needs, biomass resources available from agricultural activities, and the presence of a NGO which is competent to facilitate running of the enterprise. The trigeneration system was designed to integrate off-the-shelf equipment for power generation using boilers of approximate total capacity 1 tonne of fuel per hour, and a back-pressure steam turbo-generator (200 kW). Cooling is provided by a vapour absorption machine (VAM). Findings: The financial analysis indicates a payback time of less than two years. Nevertheless, this is sensitive to market fluctuations and availabilities of raw materials. Originality/value: Although comparable trigeneration systems already exist in large food processing industries and in space heating and cooling applications, they have not previously been used for rural micro-industry. The small-scale (1-2 m3/h output) multiple effect distillation (3 effect plus condenser) unit has not previously been deployed at field level.