Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Fast parallel algorithms for short-range molecular dynamics

Today's data centers may contain tens of thousands of computers with significant aggregate bandwidth requirements. The network architecture typically consists of a tree of routing and switching elements with progressively more specialized and expensive equipment moving up the network hierarchy. Unfortunately, even when deploying the highest-end IP switches/routers, resulting topologies may only support 50% of the aggregate bandwidth available at the edge of the network, while still incurring tremendous cost. Non-uniform bandwidth among data center nodes complicates application design and limits overall system performance.In this paper, we show how to leverage largely commodity Ethernet switches to support the full aggregate bandwidth of clusters consisting of tens of thousands of elements. Similar to how clusters of commodity computers have largely replaced more specialized SMPs and MPPs, we argue that appropriately architected and interconnected commodity switches may deliver more performance at less cost than available from today's higher-end solutions. Our approach requires no modifications to the end host network interface, operating system, or applications; critically, it is fully backward compatible with Ethernet, IP, and TCP.

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A scalable, commodity data center network architecture

Power dissipation is a fundamental problem for nanoelectronic circuits. Scaling the supply voltage reduces the energy needed for switching, but the field-effect transistors (FETs) in today's integrated circuits require at least 60 mV of gate voltage to increase the current by one order of magnitude at room temperature. Tunnel FETs avoid this limit by using quantum-mechanical band-to-band tunnelling, rather than thermal injection, to inject charge carriers into the device channel. Tunnel FETs based on ultrathin semiconducting films or nanowires could achieve a 100-fold power reduction over complementary metal-oxide-semiconductor (CMOS) transistors, so integrating tunnel FETs with CMOS technology could improve low-power integrated circuits.

Tunnel field-effect transistors as energy-efficient electronic switches

Concern about the performance of wires wires in scaled technologies has led to research exploring other communication methods. This paper examines wire and gate delays as technologies migrate from 0.18-/spl mu/m to 0.035-/spl mu/m feature sizes to better understand the magnitude of the the wiring problem. Wires that shorten in length as technologies scale have delays that either track gate delays or grow slowly relative to gate delays. This result is good news since these "local" wires dominate chip wiring. Despite this scaling of local wire performance, computer-aided design (CAD) tools must still become move sophisticated in dealing with these wires. Under scaling, the total number of wires grows exponentially, so CAD tools will need to handle an ever-growing percentage of all the wires in order to keep designer workloads constant. Global wires present a more serious problem to designers. These are wires that do not scale in length since they communicate signals across the chip. The delay of these wives will remain constant if repeaters are used meaning that relative to gate delays, their delays scale upwards. These increased delays for global communication will drive architectures toward modular designs with explicit global latency mechanisms.

The future of wires

Steep subthreshold swing transistors based on interband tunneling are examined toward extending the performance of electronics systems. In particular, this review introduces and summarizes progress in the development of the tunnel field-effect transistors (TFETs) including its origin, current experimental and theoretical performance relative to the metal-oxide-semiconductor field-effect transistor (MOSFET), basic current-transport theory, design tradeoffs, and fundamental challenges. The promise of the TFET is in its ability to provide higher drive current than the MOSFET as supply voltages approach 0.1 V.

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Low-Voltage Tunnel Transistors for Beyond CMOS Logic

A method and system for providing frame start indication in a memory system having indeterminate read data latency. The method includes receiving a data transfer and determining if the data transfer includes a frame start indicator. The method also includes capturing the data transfer and “n” subsequent data transfers in response to determining that the data transfer includes a frame start indicator. The data transfer and the “n” subsequent data transfers comprise a data frame.

Method and system for providing frame start indication in a memory system having indeterminate read data latency

According to one embodiment of the present invention, a method of constructing network communication for a grid of node groups is provided, the grid including an M dimensional grid, each node group including N nodes, wherein M is greater than or equal to one and N is greater than one, wherein each node includes a router. The method includes directly connecting each node in each node group to every other node in the node group via intra-group links and directly connecting each node in each node group of the M dimensional grid to a node in each neighboring node group in the M dimensional grid via inter-group links.

T-star interconnection network topology

A method and system for providing identification tags in a memory system having indeterminate data response times. An exemplary embodiment includes a memory controller in a memory system. The memory controller includes a mechanism for receiving data packets via an upstream channel, the data packets including upstream identification tags. The memory controller also includes a mechanism having instructions for facilitating determining if a received data packet is in response to a request from the memory controller. Input to the determining includes an upstream identification tag included in the received data packet. If the received data packet is determined to be in response to a request from the memory controller, then the received data packet is matched to the request, thereby allowing the memory controller to operate with indeterminate data response times.

Method and system for providing identification tags in a memory system having indeterminate data response times

A Planar Memory Module (PAMM) device comprising a generally planar card comprising a first side and a second side, the first side having a plurality of couplings and the second side having a plurality of connectors, a plurality of memory devices coupled to the card via a first portion of the plurality of couplings, and at least one hub chip coupled to the card via a second portion of the plurality of couplings. Each of the plurality of couplings is connected to an associated one of the plurality of connectors.

Planar array contact memory cards

A system and method for providing a memory device having a shared error feedback pin. The system includes a memory device having a data interface configured to receive data bits and CRC bits, CRC receiving circuitry, CRC creation circuitry, a memory device pad, and driver circuitry. The CRC receiving circuitry utilizes a CRC equation for the detection of errors in one or more of the received data and the received CRC bits. The CRC creation circuitry utilizes the CRC equation for the creation of CRC bits consistent with data to be transmitted to a separate device bits. The memory device pad is configured for reporting of any errors detected in the received data and the received CRC bits. The driver circuitry is connected to the memory device pad and merged with one or more other driver circuitries resident on one or more other memory devices into an error reporting line.

Paul W. Coteus

Papers

Method and system for providing frame start indication in a memory system having indeterminate read data latency

T-star interconnection network topology

Method and system for providing identification tags in a memory system having indeterminate data response times

Planar array contact memory cards

System and method for providing a memory device having a shared error feedback pin