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Hardware MPI message matching: Insights into MPI matching behavior to inform design: Hardware MPI message matching

Concurrency and Computation. Practice and Experience

Ferreira, Kurt; Grant, Ryan; Levenhagen, Michael; Levy, Scott L.N.; Groves, Taylor

Here, this paper explores key differences of MPI match lists for several important United States Department of Energy (DOE) applications and proxy applications. This understanding is critical in determining the most promising hardware matching design for any given high-speed network. The results of MPI match list studies for the major open-source MPI implementations, MPICH and Open MPI, are presented, and we modify an MPI simulator, LogGOPSim, to provide match list statistics. These results are discussed in the context of several different potential design approaches to MPI matching–capable hardware. The data illustrate the requirements for different hardware designs in terms of performance and memory capacity. Finally, this paper's contributions are the collection and analysis of data to help inform hardware designers of common MPI requirements and highlight the difficulties in determining these requirements by only examining a single MPI implementation.

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TYPE Journal Article YEAR 2019
DOIOSTI

Compressed Optimization of Device Architectures for Semiconductor Quantum Devices

Physical Review Applied

Ward, Daniel R.; Frees, Adam; Gamble, John K.; Blume-Kohout, Robin; Eriksson, M.A.; Friesen, Mark; Coppersmith, S.N.

Recent advances in nanotechnology have enabled researchers to manipulate small collections of quantum-mechanical objects with unprecedented accuracy. In semiconductor quantum-dot qubits, this manipulation requires controlling the dot orbital energies, the tunnel couplings, and the electron occupations. These properties all depend on the voltages placed on the metallic electrodes that define the device, the positions of which are fixed once the device is fabricated. While there has been much success with small numbers of dots, as the number of dots grows, it will be increasingly useful to control these systems with as few electrode voltage changes as possible. Here, we introduce a protocol, which we call the "compressed optimization of device architectures" (CODA), in order both to efficiently identify sparse sets of voltage changes that control quantum systems and to introduce a metric that can be used to compare device designs. As an example of the former, we apply this method to simulated devices with up to 100 quantum dots and show that CODA automatically tunes devices more efficiently than other common nonlinear optimizers. To demonstrate the latter, we determine the optimal lateral scale for a triple quantum dot, yielding a simulated device that can be tuned with small voltage changes on a limited number of electrodes.

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TYPE Journal Article YEAR 2019
DOIOSTI
Results 2401–2425 of 9,998
Results 2401–2425 of 9,998