An accurate prefetching policy for object oriented systems

PhD ThesisIn the latest high-performance computers, there is a growing requirement for accurate prefetching(AP) methodologies for advanced object management schemes in virtual memory and migration systems. The major issue for achieving this goal is that of finding a simple way of accurately predicting the objects that will be referenced in the near future and to group them so as to allow them to be fetched same time. The basic notion of AP involves building a relationship for logically grouping related objects and prefetching them, rather than using their physical grouping and it relies on demand fetching such as is done in existing restructuring or grouping schemes. By this, AP tries to overcome some of the shortcomings posed by physical grouping methods. Prefetching also makes use of the properties of object oriented languages to build inter and intra object relationships as a means of logical grouping. This thesis describes how this relationship can be established at compile time and how it can be used for accurate object prefetching in virtual memory systems. In addition, AP performs control flow and data dependency analysis to reinforce the relationships and to find the dependencies of a program. The user program is decomposed into prefetching blocks which contain all the information needed for block prefetching such as long branches and function calls at major branch points. The proposed prefetching scheme is implemented by extending a C++ compiler and evaluated on a virtual memory simulator. The results show a significant reduction both in the number of page fault and memory pollution. In particular, AP can suppress many page faults that occur during transition phases which are unmanageable by other ways of fetching. AP can be applied to a local and distributed virtual memory system so as to reduce the fault rate by fetching groups of objects at the same time and consequently lessening operating system overheads.British Counci

A study of sampling, granularity and localities in program restructuring

Program restructuring is a method to reduce the cost of program execution by improving the locality of the program\u27s reference behavior. Three aspects of program restructuring (sampling, granularity, localities) are studied in this research. The study of first aspect, sampling, shows that the high cost of a posteriori restructuring can be reduced considerably by a program restructuring method based on sampled reference strings rather than on complete reference string;The second aspect is granularity. Based on the studies of two different block sizes (the basic-block and the procedure block), it is found that the performance of restructuring using smaller blocks is not necessarily better;Finally, a new strategy-independent restructuring method, using both the critical and locality principles, is found to be more effective than any other existing restructuring methods;Results of measurements of paging performance obtained in the experiments are discussed. Both fixed-space and variable-space paging policies are considered

URBAN REGENERATION PROCESS - THE CASE OF GENOA, AN EXAMPLE OF INTEGRATED URBAN DEVELOPMENT APPROACH

This paper analyzes the process of Urban Regeneration in Europe and examines the factors influencing this process as well as its implementation. Foundamental changes in the economy, technology, demography and politics are reshaping the environment for cities in Europe. These changes have induced a logic of competion in a dynamic and complex context. In the attempt to become and remain an attractive place for inhabitants, city users, businessmen and visitors, cities invent their own strategies, discovering that the policies of local governments need to be more marked-oriented with an eye to the city’s weaknesses and strenghts. Many historic cities in recent decades experienced redevelopment for new “postindustrial uses” often related to culture, tourism, technology. Such uses may offer the potential for creating more sustainable and liveable cities. Especially in old industrial areas, new politics, strategies and funds have been used for re-utilization of old industrial sites. Clear examples for this is Italian case studies like Genoa. In Genoa a programme for restructuring the old harbour areas, the waterfront and the historic centre has been set up. Genoa approaches functional specialisation as a more general element in its strategy for increasing economic competitiveness. The development of transport systems, services, infrastructures, promises considerable renovation of the urban functions with a significant growth in the economy linked to cultural activities and tourism. Regeneration programmes for de-industrialised areas have promoted the location and relocation of business investments as well as actions to improve a productive diversification. At present Genoa after a deep crisis, has regained a new identity and its role in the Italian economic and social system. This paper integrates three issues. First it describes some of the main features of pattern of urban development and the increase of competition, setting the scene for a more strategic action. Second analyzes the case study Genoa, an example of integrated urban development approach. Third attention is drawn on the way in which cities “create” their own image management, using actions that shown and reveal hidden resources.

Get Out of the Valley: Power-Efficient Address Mapping for GPUs

GPU memory systems adopt a multi-dimensional hardware structure to provide the bandwidth necessary to support 100s to 1000s of concurrent threads. On the software side, GPU-compute workloads also use multi-dimensional structures to organize the threads. We observe that these structures can combine unfavorably and create significant resource imbalance in the memory subsystem causing low performance and poor power-efficiency. The key issue is that it is highly application-dependent which memory address bits exhibit high variability. To solve this problem, we first provide an entropy analysis approach tailored for the highly concurrent memory request behavior in GPU-compute workloads. Our window-based entropy metric captures the information content of each address bit of the memory requests that are likely to co-exist in the memory system at runtime. Using this metric, we find that GPU-compute workloads exhibit entropy valleys distributed throughout the lower order address bits. This indicates that efficient GPU-address mapping schemes need to harvest entropy from broad address-bit ranges and concentrate the entropy into the bits used for channel and bank selection in the memory subsystem. This insight leads us to propose the Page Address Entropy (PAE) mapping scheme which concentrates the entropy of the row, channel and bank bits of the input address into the bank and channel bits of the output address. PAE maps straightforwardly to hardware and can be implemented with a tree of XOR-gates. PAE improves performance by 1.31 x and power-efficiency by 1.25 x compared to state-of-the-art permutation-based address mapping

Rethinking the State-Local Relationship: Local Economic Development

Examines issues involved in shifting responsibility for redevelopment and enterprise zones from the state to localities, including relaxing local funding constraints to give localities more authority and incentives to support the most effective programs