Dynamic Power Management for Reactive Stream Processing on the SCC Tiled Architecture

This article is distributed under the terms of the Creative Commons Attribution 4.0 International License(http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.Dynamic voltage and frequency scaling} (DVFS) is a means to adjust the computing capacity and power consumption of computing systems to the application demands. DVFS is generally useful to provide a compromise between computing demands and power consumption, especially in the areas of resource-constrained computing systems. Many modern processors support some form of DVFS. In this article we focus on the development of an execution framework that provides light-weight DVFS support for reactive stream-processing systems (RSPS). RSPS are a common form of embedded control systems, operating in direct response to inputs from their environment. At the execution framework we focus on support for many-core scheduling for parallel execution of concurrent programs. We provide a DVFS strategy for RSPS that is simple and lightweight, to be used for dynamic adaptation of the power consumption at runtime. The simplicity of the DVFS strategy became possible by sole focus on the application domain of RSPS. The presented DVFS strategy does not require specific assumptions about the message arrival rate or the underlying scheduling method. While DVFS is a very active field, in contrast to most existing research, our approach works also for platforms like many-core processors, where the power settings typically cannot be controlled individually for each computational unit. We also support dynamic scheduling with variable workload. While many research results are provided with simulators, in our approach we present a parallel execution framework with experiments conducted on real hardware, using the SCC many-core processor. The results of our experimental evaluation confirm that our simple DVFS strategy provides potential for significant energy saving on RSPS.Peer reviewe

Configurable Integrated Monitoring System for Mobile Devices

AbstractMonitoring on smartphones and mobile devices presents several challenges, such as limited battery power and computing resources, but also provides some unique opportunities, particularly the ability to capture contextual data. Incorporating the context of the activities being monitored could improve performance modeling. Real-time monitoring could also be used to facilitate context-aware applications. In this paper, we introduce a configurable integrated monitoring solution for mobile devices. The monitoring service efficiently integrates multiple monitoring requests, and allows clients to monitor simple metrics or receive notification of custom defined events

978-1-4244-2100-8/08/$25.00 cfl2008 IEEE Wireless Reliability: Rethinking 802.11 Packet Loss

Abstract Wireless enabled devices are ubiquitous in today's computing environment. Businesses, universities, and home users alike are taking advantage of the easy deployment of wireless devices to provide network connectivity without the expense associated with wired connections. Unfortunately, the wireless medium is inherently unreliable resulting in significant work having been performed to better understand the characteristics of the wireless environment. Notably, many works attribute the primary source of wireless losses to errors in the physical medium. In contrast, our work shows that the wireless device itself plays a significant role in 802.11 packet loss. In our experiments, we found that the correlation of loss between multiple closely located (within one *) receivers is low with the majority of loss instances only occurring at one of the receivers. We conducted extensive experiments on the individual loss characteristics of five common wireless cards, showing that while the cards behave similarly on the macrolevel (e.g. similar overall loss rates), the cards perform quite differently on the micro-level (e.g. burstiness, correlation, and consistency).

DETOUR: Delay- and Energy-Aware Multi-Path Routing in Wireless Ad Hoc Networks

Abstract—Streaming real-time applications require the timely distribution of information in mobile ad-hoc and sensor networks. At the same time, such networks must operate energy-efficiently to maximize the lifetime of mobile devices and applications. In multi-hop networks, multiple communication paths between a single sender and receiver can be established, with varying real-time and energy characteristics of each path. This paper introduces the DETOUR (Delay- and Energy- aware mulTicOUrse Routing) protocol that applies feedback-driven path diversification, where traffic load is balanced across two or more paths to ensure both timeliness and energy-efficiency. We apply the (m,k) model for firm real-time communication to wireless networks, i.e., the protocol aims to meet at least m end-toend deadlines out of k packet transmissions, thereby sacrificing additional improvement in latency in order to maximize the lifetime of the network by minimizing energy consumption. The experimental results of this paper show the protocols ability to reduce energy consumptions (up to 35%) while meeting the data streams firm real-time constraints. I

Application-specific workload shaping in multimedia-enabled personal mobile devices

10.1145/1331331.1331334Transactions on Embedded Computing Systems7