, we present a novel approach combining feedback control with DVS schemes targeting hard real-time systems with dynamic workloads. Our method relies strictly on operating system support by integrating a DVS scheduler and a feedback controller within the EDF scheduling algorithm. Each task is divided

of scheduling techniques have been developed to exploit DFS and DVS for real-time systems to reduce energy consumption. These techniques exploit idle and slack time of a schedule. Idle time can be consumed bylowering the processor frequency of selected tasks while slack time allows later tasks to execute

. Our method relies strictly on operating system support by integrating a DVS scheduler and a feedback controller within the earliest-deadline-first (EDF) scheduling algorithm. Each task is divided into two portions. The objective within the first portion is to exploit frequency scaling for the average

during frequency/voltage transitions. We study several power-aware feedback schemes based on earliestdeadline-first (EDF) scheduling that adjust the system behavior dynamically for different workload characteristics. An infrastructure for investigating several hard realtime DVS schemes, including our

, DVSleak, based on earliestdeadline-first scheduling (EDF). Our method trades off DVS with leakage, where the former slows down execution while the latter intelligently defers dispatching of jobs when sleeping is beneficial. We further capitalize on feedback knowledge about actual execution times

Contemporary processors support dynamic voltage scaling (DVS) to reduce power consumption by varying processor voltage/frequency dynamically. We develop power-aware feedback-DVS algorithms for hard real-time systems that adapt to dynamically changing workloads. The algorithms lower execution speed

examine the merits of hardware/software co-design for a feedback DVS algorithm and a novel processor capable of executing instructions during frequency/voltage transitions. We study several power-aware feedback schemes based on earliest-deadline-first (EDF) scheduling that adjust the system behavior

Threads are the vehicle,for concurrency in many approaches to parallel programming. Threads separate the notion of a sequential execution stream from the other aspects of traditional UNIX-like processes, such as address spaces and I/O descriptors. The objective of this separation is to make the expression and control of parallelism sufficiently cheap that the programmer or compiler can exploit even fine-grained parallelism with acceptable overhead. Threads can be supported either by the operating system kernel or by user-level library code in the application address space, but neither approach has been fully satisfactory. This paper addresses this dilemma. First, we argue that the performance of kernel threads is inherently worse than that of user-level threads, rather than this being an artifact of existing implementations; we thus argue that managing par- allelism at the user level is essential to high-performance parallel computing. Next, we argue that the lack of system integration exhibited by user-level threads is a consequence of the lack of kernel support for user-level threads provided by contemporary multiprocessor operating systems; we thus argue that kernel threads or processes, as currently conceived, are the wrong abstraction on which to support user- level management of parallelism. Finally, we describe the design, implementation, and performance of a new kernel interface and user-level thread package that together provide the same functionality as kernel threads without compromis- ing the performance and flexibility advantages of user-level management of parallelism.

importance, is largely overlooked/under-developed. To provide real-time guarantees, DVS must consider deadlines and periodicity of real-time tasks, requiring integration with the real-time scheduler. In this paper, we present a class of novel algorithms called real-time DVS (RT-DVS) that modify the OS

Multiuser diversity is a form of diversity inherent in a wireless network, provided by independent time-varying channels across the different users. The diversity benefit is exploited by tracking the channel fluctuations of the users and scheduling transmissions to users when their instantaneous