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This paper addresses algorithms for dynamically varying (scaling) CPU speed and voltage in order to save energy. Such scaling is useful and effective when it is immaterial when a task completes, as long as it meets some deadline. We show how to modify any scaling algorithm to keep performance the same but minimize expected energy consumption. We refer to(More)
In this paper, we use real server and personal computer workloads to systematically analyze the true performance impact of various I/O optimization techniques, including read caching, sequential prefetching, opportunistic prefetching, write buffering, request scheduling, striping, and short-stroking. We also break down disk technology improvement into four(More)
Standardization of a high performance blackplane bus, so that it can accommodate boards developed by different vendors, implies the need for a standardized cache consistency protocol. In this paper we define a class of compatible consistency protocols supported by the current IEEE Futurebus design. We refer to this class as the MOESI class of protocols; the(More)
Sequentiality of access is an inherent characteristic of many database systems. We use this observation to develop an algorithm which selectively prefetches data blocks ahead of the point of reference. The number of blocks prefetched is chosen by using the empirical run length distribution and conditioning on the observed number of sequential block(More)
Computer researchers have a professional obligation to referee the work of others. This article tells you how to evaluate a paper and write a report using common standards and procedures. It focuses on research papers in applied areas of computer science and engineering, such as systems architecture, hardware, communications, and performance evaluation, but(More)
Limiting the energy consumption of computers, especially portables, is becoming increasingly important. Thus, new energy-saving computer components and architectures have been and continue to be developed. Many architectural features have both high performance and low power modes, with the mode selection under software control. The problem is to minimize(More)
The CPU is one of the major power consumers in a portable computer, and considerable power can be saved by turning off the CPU when it is not doing useful work. In Ap-ple's MacOS, however, idle time is often converted to busy waiting, and generally it is very hard to tell when no useful computation is occurring. In this paper, we suggest several heuristic(More)