15037541
Power-performance trade-off using pipeline delays
We study the delays faced by instructions in the pipeline of a superscalar processor and its impact on power and performance. Instructions that are ready-on-dispatch (ROD) are normally delayed in the issue stage due to resource constraints even though their data dependencies are satisfied. These delays are reduced by issuing ROD instructions earlier than normal and executing them on slow functional units to obtain power benefits. This scheme achieves around 6% to 8% power reduction with average performance degradation of about 2%. Alternatively, instead of reducing the delays faced by instructions in the pipeline, increasing them by deliberately stalling certain instructions at appropriate times minimizes the duration for which the processor is underutilized leading to 2.5-4% power savings with less than 0.3% performance degradation.
13275687
Exploiting program execution phases to trade power and performance for media workload
Processing streaming media comprises several program phases (often distinct) that are periodic and independent of application data. In this paper we characterize execution of such programs into execution phases based on their dynamic IPC (Instruction Per Cycle) profile. We show that program execution of selected phases can be dynamically boosted by activating additional standby functional units which ae otherwise powered down for saving energy. Through simulation we show that speedup ranging from 1.1 to 1.25 can be achieved while reducing the energy-delay product (EDP) for most of the media benchmarks evaluated. Additionally we show that artificially introduced stalls during phases of processor underutilization reduces power by around 2 to 4%.
14498501
A clustering scheme for hierarchical control in multi-hop wireless networks
In this paper we present a clustering scheme to create a hierarchical control structure for multi-hop wireless networks. A cluster is defined as a subset of vertices, whose induced graph is connected. In addition, a cluster is required to obey certain constraints that are useful for management and scalability of the hierarchy. All these constraints cannot be met simultaneously for general graphs, but we show how such a clustering can be obtained for wireless network topologies. Finally, we present an efficient distributed implementation of our clustering algorithm for a set of wireless nodes to create the set of desired clusters.
15094516
Translating application requirements to ATM cell level requirements
It has been well established that high speed networks will be based on cell relay technology, an important feature of which is small fixed size packets. However, application data is rarely small of fixed size, and hence it is important to study the impact on message-level performance in a cell based system. This paper presents a simulation study of application level performance and studies various trade-offs in requesting specific cell level QoS parameters to satisfy the application requirements.
16477654
Efficient peer location on the Internet
We consider the problem of locating nearby application peers over the Internet. We define a new peer-location scheme (called Tiers), that scales to large application peer groups. Tiers creates a hierarchy of peers, and provides an efficient and scalable solution to the peer-location problem. Tiers can be implemented entirely in the application-layer and does not require the deployment of either any additional measurement services, or well-known reference points in the network.We have evaluated the performance of Tiers through detailed experiments. Our results show that Tiers is able to locate the nearest peers quickly (≪ 1 s) and accurately on wide-area Internet-like topologies. We have also compared the performance of Tiers with two other schemes, Beaconing and Distributed Binning, both of which are known to have good performance. Both these techniques are reference-points based schemes and are efficient for overlays with a small number of peers (e.g. ≤32). Our results show that Tiers significantly outperforms both these schemes. Tiers is particularly efficient for large overlay networks, has an order of magnitude lower control overhead for overlays with 512 peers and still achieves greater accuracy in locating the nearest peers.
20080343
A survey of adaptive bandwidth control algorithms
In packet-switched network traffic management and control, efficiently allocating bandwidth to provide quantitative packet-level QoS to aggregate traffic has been difficult due to unpredictable, unknown statistical characteristics of the aggregate traffic. With inaccurate traffic information, using static bandwidth allocation results in the network being underutilized, or the QoS requirement not being satisfied. An alternative is to use adaptive bandwidth control (ABC), whereby the allocated bandwidth is regularly adjusted over the packet-level time scale to attain a given QoS requirement. This paper provides a literature review of ABC algorithms that guarantee aggregate traffic packet-level QoS metrics, such as the average queue length, packet loss, and packet delay. We describe different ABC algorithms, identify their advantages and shortcomings, and provide some comparative performance evaluation results. Open issues in ABC for future research directions are also discussed.
456730
Fast replication in content distribution overlays
We present SPIDER-a system for fast replication or distribution of large content from a single source to multiple sites interconnected over Internet or via a private network. In order to exploit spatial diversity of the underlying network, SPIDER uses an overlay structure composed of dedicated transit nodes (TNs). The data transport mechanism in SPIDER leverages this overlay structure to provide a coordinated approach that minimizes the maximum time to replicate to all destination sites (the make span of content replication). In order to achieve this objective, SPIDER employs two orthogonal components: a) creation of multiple dynamic distribution trees using the transit nodes b) end-to-end reliable data transport with flow control on these trees by chaining point-to-point TCPs. We further present simulations based results to quantify benefits of tree construction algorithms in random topologies. We evaluate the real implementation of the SPIDER in Planet Lab and observe a 2-6 times speed up compared to different existing schemes.