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Jacobsen, Douglas

Publications and source records attributed to Jacobsen, Douglas.

5 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

NERSC Slurm Software Configurations and Plugins

This software can be used to tune the HPC operations of a Cray system running Slurm workload manager software. This includes many of the customizations that NERSC has made over the past three years. In particular these customizations allow for complex site-local policies to be implemented and managed in a scalable way, or add unique capabilities to slurm via our plugins, including: * performance software integration and compute node staging * temporary directory/dynamic user content management automation * software defined networking integration

Jacobsen, Douglas↗
DOE OSTI2018

MPAS-Albany Land Ice (MALI): a variable-resolution ice sheet model for Earth system modeling using Voronoi grids

Abstract. We introduce MPAS-Albany Land Ice (MALI) v6.0, a new variable-resolution land ice model that uses unstructured Voronoi grids on a plane or sphere. MALI is built using the Model for Prediction Across Scales (MPAS) framework for developing variable-resolution Earth system model components and the Albany multi-physics code base for the solution of coupled systems of partial differential equations, which itself makes use of Trilinos solver libraries. MALI includes a three-dimensional first-order momentum balance solver (Blatter–Pattyn) by linking to the Albany-LI ice sheet velocity solver and an explicit shallow ice velocity solver. The evolution of ice geometry and tracers is handled through an explicit first-order horizontal advection scheme with vertical remapping. The evolution of ice temperature is treated using operator splitting of vertical diffusion and horizontal advection and can be configured to use either a temperature or enthalpy formulation. MALI includes a mass-conserving subglacial hydrology model that supports distributed and/or channelized drainage and can optionally be coupled to ice dynamics. Options for calving include eigencalving , which assumes that the calving rate is proportional to extensional strain rates. MALI is evaluated against commonly used exact solutions and community benchmark experiments and shows the expected accuracy. Results for the MISMIP3d benchmark experiments with MALI's Blatter–Pattyn solver fall between published results from Stokes and L1L2 models as expected. We use the model to simulate a semi-realistic Antarctic ice sheet problem following the initMIP protocol and using 2 km resolution in marine ice sheet regions. MALI is the glacier component of the Energy Exascale Earth System Model (E3SM) version 1, and we describe current and planned coupling to other E3SM components.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2015

Parallel performance optimizations on unstructured mesh-based simulations

This paper addresses two key parallelization challenges the unstructured mesh-based ocean modeling code, MPAS-Ocean, which uses a mesh based on Voronoi tessellations: (1) load imbalance across processes, and (2) unstructured data access patterns, that inhibit intra- and inter-node performance. Our work analyzes the load imbalance due to naive partitioning of the mesh, and develops methods to generate mesh partitioning with better load balance and reduced communication. Furthermore, we present methods that minimize both inter- and intranode data movement and maximize data reuse. Our techniques include predictive ordering of data elements for higher cache efficiency, as well as communication reduction approaches. We present detailed performance data when running on thousands of cores using the Cray XC30 supercomputer and show that our optimization strategies can exceed the original performance by over 2×. Additionally, many of these solutions can be broadly applied to a wide variety of unstructured grid-based computations.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2015

shifter

Shifter enables application virtualization or containerization in large-scale HPC environments. This technology decreases the effort to port applications to or between HPC sites while increasing reproducibility and scientific productivity. Shifter works by converting application/container images to a common format, and then leverages basic Linux functionality to make that image available to batch jobs run in the HPC environment.

Jacobsen, Douglas↗
DOE OSTI2015

shifter

Shifter enables application virtualization or containerization in large-scale HPC environments. This technology decreases the effort to port applications to or between HPC sites while increasing reproducibility and scientific productivity. Shifter works by converting application/container images to a common format, and then leverages basic Linux functionality to make that image available to batch jobs run in the HPC environment.

Jacobsen, Douglas↗