José Carlos Sancho

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Roadrunner is a 1.38 Pflop/s-peak (double precision) hybrid-architecture supercomputer developed by LANL and IBM. It contains 12,240 IBM PowerXCell 8i processors and 12,240 AMD Opteron cores in 3,060 compute nodes. Roadrunner is the first supercomputer to run Linpack at a sustained speed in excess of 1 Pflop/s. In this paper we present a detailed(More)
We describe the software architecture, technical features, and performance of TICK (Transparent Incremental Checkpointer at Kernel level), a system-level checkpointer implemented as a kernel thread, specifically designed to provide fault tolerance in Linux clusters. This implementation, based on the 2.6.11 Linux kernel, provides the essential functionality(More)
Networks of workstations (NOWs) are being considered as a costeffective alternative to parallel computers. Many NOWs are arranged as a switchbased network with irregular topology, which makes routing and deadlock avoidance quite complicated. Current proposals use the up∗/down∗ routing algorithm to remove cyclic dependencies between channels and avoid(More)
Most standard cluster interconnect technologies are flexible with respect to network topology. This has spawned a substantial amount of research on topology-agnostic routing algorithms, which make no assumption about the network structure, thus providing the flexibility needed to route on irregular networks. Actually, such an irregularity should be often(More)
InfiniBand is very likely to become the facto standard for communication between processing nodes and I/O devices as well as for interprocessor communication. The InifiniBand Architecture (IBA) defines a switch-based network with point-to-point links that support any topology defined by the user. Routing in IBA is distributed based on forwarding tables, and(More)
In this work we present an initial performance evaluation of Intel's latest, secondgeneration quad-core processor, Nehalem, and provide a comparison to first-generation AMD and Intel quad-core processors Barcelona and Tigerton. Nehalem is the first Intel processor to implement a NUMA architecture incorporating QuickPath Interconnect for interconnecting(More)
Networks of workstations (NOWs) are being considered as a cost-effective alternative to parallel computers. Most NOWs are arranged as a switch-based network and provide mechanisms for discovering the network topology. Hence, they provide support for both regular and irregular topologies, which makes routing and deadlock avoidance quite complicated. Current(More)
The InfiniBand Architecture (IBA) defines a switchbased network with point-to-point links whose topology is arbitrarily established by the customer. Often, the interconnection pattern is irregular, which complicates routing and deadlock avoidance. Current routing algorithms for NOWs, either achieve a low network performance, such as the up*/down* routing(More)
In order to take full advantage of multi-core processors careful attention must be given to the way in which each core interacts with main memory. In data-rich parallel applications multiple transfers between the main memory and local memory (cache or other) of each core will be required. It will be increasingly important to overlap these data transfers(More)