Parallel Logic Programs on the HP Mayfly

19 pagesThe Mayfly, a parallel processor being built at HP Labs in Palo Alto, has architectural support for several import.ant. aspects of the OM virtual machine for parallel logic programs. Each node has a coprocessor that is able to relieve the main processor of a significant amount oft.he "housekeeping" work of memory management , task switching, and message handling. This paper describes how the coprocessor implements kernel level functions in OM, with particular attention to the operations that support task switching. The paper includes detailed timing data from a program with interleaved parallel threads to show that while the main processor is busy in one thread the coprocessor can effectively build the context for the next thread

Concurrent Scheme

Journal ArticleThis paper describes an evolution of the Scheme language to support parallelism with tight coupling of control and data. Mechanisms are presented to address the difficult and related problems of mutual exclusion and data sharing which arise in concurrent language systems. The mechanisms are tailored to preserve Scheme semantics as much as possible while allowing for efficient implementation. Prototype implementations of the resulting language are described which have been completed. A third implementation is underway for the Mayfly, a distributed memory, twisted-torus communication topology, parallel processor, under development at the Hewlett-Packard Research Laboratories. The language model is particularly well suited for the Mayfly processor, as will be shown

Program and Abstracts of the Annual Meeting of the Georgia Academy of Science, 2015

The annual meeting of the Georgia Academy of Science took place March 13-14, 2015, at Georgia College & State University, Milledgeville, Georgia. The keynote speaker was Dr. Chryssa Kouveliotou of UA-Huntsville and the Marshall Space Center. Her presentation was entitled The Transient High-Energy Sky. Additional presentations were provided by members of the Academy who represented the following sections: I. Biological Sciences II Chemistry III. Earth & Atmospheric Sciences IV. Physics, Mathematics, Computer Science, Engineering & Technology V. Biomedical Sciences VI. Philosophy & History of Science VII. Science Education VIII. Anthropolog

Microgrids/Nanogrids Implementation, Planning, and Operation

Today’s power system is facing the challenges of increasing global demand for electricity, high-reliability requirements, the need for clean energy and environmental protection, and planning restrictions. To move towards a green and smart electric power system, centralized generation facilities are being transformed into smaller and more distributed ones. As a result, the microgrid concept is emerging, where a microgrid can operate as a single controllable system and can be viewed as a group of distributed energy loads and resources, which can include many renewable energy sources and energy storage systems. The energy management of a large number of distributed energy resources is required for the reliable operation of the microgrid. Microgrids and nanogrids can allow for better integration of distributed energy storage capacity and renewable energy sources into the power grid, therefore increasing its efficiency and resilience to natural and technical disruptive events. Microgrid networking with optimal energy management will lead to a sort of smart grid with numerous benefits such as reduced cost and enhanced reliability and resiliency. They include small-scale renewable energy harvesters and fixed energy storage units typically installed in commercial and residential buildings. In this challenging context, the objective of this book is to address and disseminate state-of-the-art research and development results on the implementation, planning, and operation of microgrids/nanogrids, where energy management is one of the core issues

Instituting the Common in the Artistic Circulation: From Entrepreneurship of the Self to Entrepreneurship of the Multitude

In this paper I trace the contradictions embedded in global artistic circulation, which is dialectically analysed as a nexus of exploitation and a site where the commons can be instituted. To enable this argument, I synthesise the methodologies of dialectical materialism, the sociology of art and action research, supplementing a theoretical overview of systemic pressures with a keen observation of the social practices that emerge in critical response to it. Basing my analysis on empirical evidence, I examine social conflicts, triggered by the extracting value from the distributed labour of artistic networks, as political opportunities to be seized by progressive art workers. Thus, I propose a new perspective on current processes of incorporating contemporary art into the late-capitalist cycles of accumulation and modes of establishing and reproducing social distinctions. Instead of mourning for – presumably lost but still positively valorised – artistic autonomy, I argue for a revamping of the apparatuses regulating artistic circulation for the sake of the labouring multitudes

Avalanche: A communication and memory architecture for scalable parallel computing

technical reportAs the gap between processor and memory speeds widens, system designers will inevitably incorporate increasingly deep memory hierarchies to maintain the balance between processor and memory system performance. At the same time, most communication subsystems are permitted access only to main memory and not a processor's top level cache. As memory latencies increase, this lack of integration between the memory and communication systems will seriously impede interprocessor communication performance and limit effective scalability. In the Avalanche project we are redesigning the memory architecture of a commercial RISC multiprocessor, the HP PA-RISC 7100, to include a new multi-level context sensitive cache that is tightly coupled to the communication fabric. The primary goal of Avalanche's integrated cache and communication controller is attacking end to end communication latency in all of its forms. This includes cache misses induced by excessive invalidations and reloading of shared data by write-invalidate coherence protocols and cache misses induced by depositing incoming message data in main memory and faulting it into the cache. An execution-driven simulation study of Avalanche's architecture indicates that it can reduce cache stalls by 5-60% and overall execution times by 10-28%

Neverlast: Towards the Design and Implementation of the NVM-based Everlasting Operating System

Novel non-volatile memory (NVM) technologies allow for the efficient implementation of \u27\u27intermittently-powered\u27\u27 smart dust and edge computing systems in a previously unfamiliar way. Operating with rough environmental conditions where power-supply failures occur often requires adjustments to all parts of the system. This leads to an inevitable trade-off in the design of operating systems -- the overhead of persisting the achieved computation progress over power failures is detrimental to the possible amount of progress with the available energy budgets. It is, therefore, crucial to minimize the overhead of ensuring persistence. This paper presents the case that persistence should be provided as an operating-system service to achieve everlasting operating capabilities. Triggered by power-failure interrupts, an implicit persistence service for the processor status of a process preserves progress on the CPU-instruction level. This interrupt only triggers if necessary so that no power-state polling is needed. We outline architectures for everlasting systems and discuss their benefits and drawbacks compared to existing approaches. Thereby, the operating system provides persistence as a service at run-time to the application, with minimal overhead. Our approach enables the separation of the application from energy-supply state estimation, as well as state-preserving logic for software and hardware components

Development of a Hydrodynamic and Sediment Transport Model for Green Bay, Lake Michigan

Sediment dynamics are strongly linked with biogeochemical and physical changes in estuarine systems. Understanding the links between sediment processes and ecosystem responses is necessary for the restoration of degraded systems. Located in Northern US, and one of the largest freshwater estuaries on earth, Green Bay is a distinct example of these degraded systems. Rapid development and anthropogenic activities increased nutrient loading rates into the bay and led to a major disruption of the pre-existing biogeochemical regimes in the ecosystem. Contaminated and nutrient-rich sediments were discharged to the bay by the Fox River for almost half a century. Green Bay’s seasonal-, morphological-, and physically-restricted mixing is unable to export a significant portion of the supplied materials to Lake Michigan, i.e., Green Bay behaves as an efficient retention basin for the lake. Therefore, several environmental and human-health related issues such as hypoxia, eutrophication, degraded water quality, and harmful algal blooms developed in Green Bay, turning the southern bay into a USEPA area of concern since the 1980s. Restoration programs were consequently developed, including the development of monitoring programs and intensive collection of field data, research projects, and remedial action plans. Several of these efforts have highlighted the importance and usefulness of nutrient and toxic management practices as they relate to sediment processes. Robust models that simulate sediment transport and system biogeochemistry can be instrumental in the improvement of our understanding of these linked processes and the pace of restoration efforts. Previous research has studied the circulation, thermal regime and water quality in Green Bay, using models based on the Princeton Ocean Model and the Environmental Fluid Dynamics Code. Obstacles in those studies included shortage of field measurements and model limitations. Modeling challenges included the creation of boundary conditions for nested models, use of structured grids, modeling stratified flows in shallow areas, and limited model documentation. In this study, a state-of-the-art modeling platform, Finite-Volume Community Ocean Model (FVCOM), is adopted to investigate circulation patterns, surface waves, and 3D sediment dynamics in Lake Michigan, and Green Bay in particular. The FVCOM model runs in parallel mode, with notable advantages in computational efficiency. A well-calibrated and verified physically based hydrodynamic and sediment transport model has several practical applications for the management of the system, including but not limited to, explaining patterns and rates of sediment dynamics, predicting the short- and long-term effects of the restoration plans, providing simulations and early warning forecasts of the potential fate and transport of pollutants, and modeling the hypoxic dead zones within the bay