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Cloud computing based on system virtualization, has been expanding its services to distributed data-intensive platforms such as MapReduce and Hadoop. Such a distributed platform on clouds runs in a virtual cluster consisting of a number of virtual machines. In the virtual cluster, demands on computing resources for each node may fluctuate, due to data locality and task behavior. However, current cloud services use a static cluster configuration, fixing or manually adjusting the computing capability of each virtual machine (VM). The fixed homogeneous VM configuration may not adapt to changing resource demands in individual nodes.In this paper, we propose a dynamic VM reconfiguration technique for data-intensive computing on clouds, called Dynamic Resource Reconfiguration (DRR). DRR can adjust the computing capability of individual VMs to maximize the utilization of resources. Among several factors causing resource imbalance in the Hadoop platforms, this paper focuses on data locality. Although assigning tasks on the nodes containing their input data can improve the overall performance of a job significantly, the fixed computing capability of each node may not allow such locality-aware scheduling. DRR dynamically increases or decreases the computing capability of each node to enhance locality-aware task scheduling. We evaluate the potential performance improvement of DRR on a 100-node cluster, and its detailed behavior on a small scale cluster with constrained network bandwidth. On the 100-node cluster, DRR can improve the throughput of Hadoop jobs by 15% on average, and 41% on the private cluster with the constrained network connection.

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A cost-efficient network-on-chip is needed in a scalable many-core systems. Recent multicore processors have leveraged a ring topology and hierarchical ring can increase scalability but presents different challenges, including higher hop count and global ring bottleneck. In this work, we describe a hierarchical ring topology that we refer to as a transportationnetwork-inspired network-on-chip (tNoC) that leverages principles from transportation network systems. In particular, we propose a novel hybrid flow control for hierarchical ring topology to scale the topology efficiently. The flow control is hybrid in that the channels are allocated on flit granularity while the buffers are allocated on packet granularity. The hybrid flow control enables a simplified router microarchitecture (to minimize per-hop latency) as router input buffers are minimized and buffers are pushed to the edges, either at the output ports or at the hub routers that interconnect the local rings to the global ring -while still supporting virtual channels to avoid protocol deadlock. We also describe a packet-quota-system (PQS) and a separate credit network that provide congestion management, support prioritized arbitration in the network, and provide support for multiflit packets. A detailed evaluation of a 64-core CMP shows that the tNoC improves performance by up to 21% compared with a baseline, buffered hierarchical ring topology while reducing NoC energy by 51%.