14115714
Energy-efficient compressed address transmission
To realize energy-efficient buses in current nanometer-scale technologies, techniques like compression or encoding that exploit information redundancy have been explored. However, available compression techniques for buses do not always ensure energy-efficient transmission of compressed information. In this work, we present various techniques that can be used with compression schemes for buses to ensure high energy efficiency. Our best scheme, applied to a stream of 38-bit addresses issued in a typical microprocessor, yields about 14.7% energy reduction on the average across a wide range of compressed bus widths ranging and over many SPEC CPU2000 benchmarks. Our proposed techniques especially perform better - up to 28.8% energy reduction is obtained - for narrower bus widths in the range 8-16 bits.
43415133
The performance advantage of applying compression to the memory system
The memory system stores information comprising primarily instructions and data and secondarily address information, such as cache tag fields. It interacts with the processor by supporting related traffic (again comprising addresses, instructions, and data). Continuing exponential growth in processor performance, combined with technology, architecture, and application trends, place enormous demands on the memory system to permit this information storage and exchange at a high-enough performance (i.e., to provide low latency and high bandwidth access to large amounts of information). This paper comprehensively analyzes the redundancy in the information (addresses, instructions, and data) stored and exchanged between the processor and the memory system and evaluates the potential of compression in improving performance of the memory system. Analysis of traces obtained with Sun Microsystems' Shade simulator simulating SPARC executables of nine integer and six floating-point programs in the SPEC CPU2000 benchmark suite yield impressive results. Well-designed compression schemes may provide benefits in performance that far outweigh the extra time and logic for compression and decompression. This will be more so in the future since the speed and size of logic (which will be used to perform compression/decompression) are improving and are projected to improve at a much higher rate compared to those of interconnect (which will be used to communicate the information), both on-chip and off-chip.
14860014
Self-scheduling on distributed-memory machines
The authors present a general approach of self-scheduling a non-uniform parallel loop on a distributed-memory machine. The approach has two phases: a static scheduling phase and a dynamic scheduling phase. In addition to reduce scheduling overhead, using the static scheduling phase allows the data needed by the statically scheduled iterations to be prefetched. The dynamic scheduling phase balances the workload. Data distribution methods for self-scheduling are also the focus of this paper. The authors classify the data distribution methods into four categories and present partial duplication, a method that allows the problem size to grow linearly in the number of processors. The experiments conducted on a 64-node NCUBE show that as much as 79% improvement is achieved over static scheduling on the generation of a false-color image.
16580627
Handling Safety-Related Feature Interaction in Safety-Critical Product Lines
The variation management of software product lines is currently handled without adequately taking safety or other system-level properties into account. This is largely due to (1) the fact that the available product-line variation-management techniques lack sufficient support for representing the combined effect of different features, and (2) the existing feature interaction techniques do not suffice for handling one-to-many feature interactions typical of many safety-critical product lines. The challenge is that we need to track the safety-related feature interactions while still promoting reuse. The expected contribution of this work is to demonstrate how safety-related feature interactions can be better investigated and managed by the safety-analysis guided, model-based approach described in this paper.
7555324
BioProspector: Discovering Conserved DNA Motifs in Upstream Regulatory Regions of Co-Expressed Genes
The development of genome sequencing and DNA microarray analysis of gene expression gives rise to the demand for data-mining tools. BioProspector, a C program using a Gibbs sampling strategy, examines the upstream region of genes in the same gene expression pattern group and looks for regulatory sequence motifs. BioProspector uses zero to third-order Markov background models whose parameters are either given by the user or estimated from a specified sequence file. The significance of each motif found is judged based on a motif score distribution estimated by a Monte Carlo method. In addition, BioProspector modifies the motif model used in the earlier Gibbs samplers to allow for the modeling of gapped motifs and motifs with palindromic patterns. All these modifications greatly improve the performance of the program. Although testing and development are still in progress, the program has shown preliminary success in finding the binding motifs for Saccharomyces cerevisiae RAP1, Bacillus subtilis RNA polymerase, and Escherichia coli CRP. We are currently working on combining BioProspector with a clustering program to explore gene expression networks and regulatory mechanisms.
9603853
COPACC: A Cooperative Proxy-Client Caching System for On-Demand Media Streaming
Proxy caching is a key technique to reduce transmission cost for on-demand multimedia streaming. However, its effectiveness is limited by the insufficient storage space and weak cooperations among proxies and their clients. In this paper, we propose COPACC, a novel cooperative proxy-and-client caching system that combines the advantages of both proxy caching and peer-to-peer (P2P) client communications. We propose a comprehensive suite of protocols to facilitate the interactions among different network entities in COPACC. We also develop an efficient cache allocation algorithm to minimize the aggregated transmission cost of the whole system. Simulation results demonstrate that COPACC achieves remarkably lower transmission cost. Moreover, it is much more robust than a pure P2P system in the presence of node failures.
9274730
Agent-based, energy efficient routing in sensor networks
Amorphous computing aims at discovering new approaches for programming and controlling vast number of computational entities. So far, most related studies are mainly on the problem of pattern formation. However, there still remains a great challenge: how to enable amorphous entities to handle computationally hard problems? In order to tackle this challenge, we propose to take the energy efficient routing problem in sensor networks as a special topic for study, due to the similar characteristics of sensor nodes and amorphous entities. In the paper, each data packet sent from a source node is carried by an autonomous mobile data agent, which can make its own routing decision based on its local information. Moreover, we propose a novel data routing idea on energy efficient route choosing. Simulation results demonstrate that our routing schemes based on the proposed idea can achieve a better performance of energy load balancing in the network, and a shorter time delay for data agents to travel from a source to a sink than other schemes discussed in the paper. Furthermore, by endowing the data agents with some intelligence, data aggregation can be performed locally and dynamically during their transmissions in sensor networks.