Search NASA⌕ Search

SEARCH · Search NASA

Results for “threads”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 865 records · Page 48
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Effect of p-doping on the intensity noise of epitaxial quantum dot lasers on silicon

This work experimentally investigates the impact of p-doping on the relative intensity noise (RIN) properties and subsequently on the modulation properties of semiconductor quantum dot (QD) lasers epitaxially grown on silicon. Owing to the low threading dislocation density and the p-modulation doped GaAs barrier layer in the active region, the RIN level is found very stable with temperature with a minimum value of − <#comment/> 150 d B / H z . The dynamical features extracted from the RIN spectra show that p-doping between zero and 20 holes/dot strongly modifies the modulation properties and gain nonlinearities through increased internal losses in the active region and thereby hinders the maximum achievable bandwidth. Overall, this Letter is important for designing future high-speed and low-noise QD devices integrated in future photonic integrated circuits.

Duan, Jianan (ORCID:0000000177104287)↗
DOE OSTI2020

Multiple social platforms reveal actionable signals for software vulnerability awareness: A study of GitHub, Twitter and Reddit

Software vulnerabilities are flaws in computer systems that leave users open to attack. In many cases, these vulnerabilities go unnoticed and remain unresolved in codebases. Thus, awareness of software vulnerabilities among the public is crucial to ensure effective cybersecurity practices, the development of high quality software, and ultimately national security. This awareness can be better understood by studying the spread and evolution of software vulnerability discussions in online communities. This work is the first to evaluate and contrast how discussions about software vulnerabilities spread on three social platforms -- Twitter, GitHub, and Reddit. To lay the groundwork, we showcase a novel fundamental framework for measuring information spread that identifies the spread mechanisms and observables across platforms, the units of information, and the groups of measurements that can be applied to focus on a specific phenomena e.g., information cascades. We then analyze and contrast social network topologies for three example social networks and measure the scale and speed of the spread of discussion of specific vulnerabilities to understand how far and how widely they spread, how many users participate in discussions, and the duration of their spread. To demonstrate the awareness of more impactful software vulnerabilities, a subset of our analysis focuses on vulnerabilities targeted during recent major cyber attacks as well as vulnerabilities exploited by advanced persistent threat groups. We discover that usually, vulnerability discussions start on GitHub, before occurring on Twitter and Reddit. While studying how some user-level and content-level characteristics influence vulnerability spread, we observe that Twitter discussions started by users predicted to be humans have larger size, breadth, depth, adoption rate, lifetime, and structural virality compared to those started by users predicted to be bots. On Reddit, we contrast the differences in thread structure that originate from posts with positive, negative and neutral polarity. We find that posts that are positive have larger, deeper and wider discussions compared to negative and neutral posts. We anticipate the results of our analysis to not only increase the understanding of software vulnerability awareness but also inform models for simulating information spread across multiple social environments online.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2021

ParChain: a framework for parallel hierarchical agglomerative clustering using nearest-neighbor chain

This paper studies the hierarchical clustering problem, where the goal is to produce a dendrogram that represents clusters at varying scales of a data set. We propose the ParChain framework for designing parallel hierarchical agglomerative clustering (HAC) algorithms, and using the framework we obtain novel parallel algorithms for the complete linkage, average linkage, and Ward's linkage criteria. Compared to most previous parallel HAC algorithms, which require quadratic memory, our new algorithms require only linear memory, and are scalable to large data sets. ParChain is based on our parallelization of the nearest-neighbor chain algorithm, and enables multiple clusters to be merged on every round. We introduce two key optimizations that are critical for efficiency: a range query optimization that reduces the number of distance computations required when finding nearest neighbors of clusters, and a caching optimization that stores a subset of previously computed distances, which are likely to be reused. Experimentally, we show that our highly-optimized implementations using 48 cores with two-way hyper-threading achieve 5.8--110.1x speedup over state-of-the-art parallel HAC algorithms and achieve 13.75--54.23x self-relative speedup. Compared to state-of-the-art algorithms, our algorithms require up to 237.3x less space. Our algorithms are able to scale to data set sizes with tens of millions of points, which existing algorithms are not able to handle.

Computer Science↗
DOE OSTI2021

Theoretically and practically efficient parallel nucleus decomposition

This paper studies the nucleus decomposition problem, which has been shown to be useful in finding dense substructures in graphs. We present a novel parallel algorithm that is efficient both in theory and in practice. Our algorithm achieves a work complexity matching the best sequential algorithm while also having low depth (parallel running time), which significantly improves upon the only existing parallel nucleus decomposition algorithm (Sariyüce et al. , PVLDB 2018). The key to the theoretical efficiency of our algorithm is a new lemma that bounds the amount of work done when peeling cliques from the graph, combined with the use of a theoretically-efficient parallel algorithms for clique listing and bucketing. We introduce several new practical optimizations, including a new multi-level hash table structure to store information on cliques space-efficiently and a technique for traversing this structure cache-efficiently. On a 30-core machine with two-way hyper-threading on real-world graphs, we achieve up to a 55x speedup over the state-of-the-art parallel nucleus decomposition algorithm by Sariyüce et al. , and up to a 40x self-relative parallel speedup. We are able to efficiently compute larger nucleus decompositions than prior work on several million-scale graphs for the first time.

Computer Science↗
DOE OSTI2018

Automatic identification and classification of Palomar Transient Factory astrophysical objects in GLADE

Palomar Transient Factory (PTF) is a comprehensive detection system for the identification and classification of transient astrophysical objects. In this paper, we make two significant contributions to the PTF pipeline. First, we present an experimental study that evaluates a novel implementation of the real-time classifier in GLADE - a parallel data processing system that combines the efficiency of a database with the extensibility of map-reduce. We show how each stage in the classifier maps optimally into GLADE tasks by taking advantage of the unique features of the system - range-based data partitioning, columnar storage, multi-query execution, and in-database support for complex aggregate computation. Second, we introduce a novel parallel similarity join algorithm for advanced transient classification. In conclusion, we implement this algorithm in GLADE and execute it on a massive supercomputer with more than 3,000 threads, achieving more than three orders of magnitude improvement over the PostgreSQL solution.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

Seismic Tomography 2024

Seismic tomography is the most abundant source of information about the internal structure of the Earth at scales ranging from a few meters to thousands of kilometers. It constrains the properties of active volcanoes, earthquake fault zones, deep reservoirs and storage sites, glaciers and ice sheets, or the entire globe. It contributes to outstanding societal problems related to natural hazards, resource exploration, underground storage, and many more. The recent advances in seismic tomography are being translated to nondestructive testing, medical ultrasound, and helioseismology. Nearly 50 yr after its first successful applications, this article offers a snapshot of modern seismic tomography. Focused on major challenges and particularly promising research directions, it is intended to guide both Earth science professionals and early-career scientists. The individual contributions by the coauthors provide diverse perspectives on topics that may at first seem disconnected but are closely tied together by a few coherent threads: multiparameter inversion for properties related to dynamic processes, data quality, and geographic coverage, uncertainty quantification that is useful for geologic interpretation, new formulations of tomographic inverse problems that address concrete geologic questions more directly, and the presentation and quantitative comparison of tomographic models. Finally, it remains to be seen which of these problems will be considered solved, solved to some extent, or practically unsolvable over the next decade.

58 GEOSCIENCES↗
DOE OSTI2020

Multiple Synchrotron Light Monitors for Transverse Matching and Monitoring at CEBAF

Beam setup at the Continuous Electron Beam Accelerator Facility (CEBAF) involves threading beam through the machine and monitoring global transfer functions to identify and address cumulative lattice errors. Transverse beam emittance may grow by as much as two orders of magnitude, mediated by synchrotron radiation. Re-matching the enlarged beam phase space into successive re-circulation arcs minimizes this emittance growth but requires knowledge of the actual beam distribution. This is now accomplished through quadrupole scans using wire profile monitors, the most time-consuming activity in our setup process. We propose to use Synchrotron Light Monitors (SLMs) to image the beam at homologous points in the four super-period recirculation arc lattices. Benefits include real-time monitoring of beam parameters and reduced elapsed time for initial setup.These SLMs will be installed in Arc 7 of the CEBAF machine, where Synchrotron Radiation contributes moderately to emittance growth. One of four required SLMs will be installed and commissioned this year, with the rest being installed next year.

Freeman, B.↗
DOE OSTI2018

Architectural considerations for recirculated and energy recovered hard XFEL drivers

A confluence of events motivates discussion of design options for hard XFEL driver accelerators. Firstly, multiple superconducting radio-frequency (SRF) driven systems are now online (European XFEL), in construction (LCLS-II), or in design (MARIE); these provide increasing evidence of the transformational potential they offer for fundamental science with its concomitant benefits. Secondly, operation of 12 GeV CEBAF* validates use of recirculation in high energy SRF linacs. Thirdly, advances in the analysis and control of effects such as coherent synchrotron radiation (CSR) and the microbunching instability (uBI) have been recently achieved. Collectively, these developments offer insights providing extended facility science reach, reduced costs, multiplicity (i.e., support of numerous FELs operating over a range of wavelengths), and enhanced scalability and upgradability (to higher powers and energies). We will discuss the relationship amongst the various threads, and indicate how they inform design choices for the system architecture of an option for the UK-XFEL** - that of a staged multi-user X-ray FEL and nuclear physics facility based on a multi-pass recirculating SRF CW linac.

Benson, Stephen V.↗
DOE OSTI2017

MPAS-Ocean NESAP Status Report

NESAP performance improvements on MPAS-Ocean have resulted in a 5% to 7% speed-up on each of the examined systems including Cori-KNL, Cori-Haswell, and Edison. These tests were configured to emulate a production workload by using 128 nodes and a high-resolution ocean domain. Overall, the gap between standard and many-core architecture performance has been narrowed, but Cori-KNL remains considerably under-performing relative to Edison. NESAP code alterations affected 600 lines of code, and most of these improvements will benefit other MPAS codes (sea ice, land ice) that are also components within ACME. Modifications are fully tested within MPAS. Testing in ACME across many platforms is underway, and must be completed before the code is merged. In addition, a ten-year production ACME global simulation was conducted on Cori-KNL in late 2016 with the pre-NESAP code in order to test readiness and configurations for scientific studies. Next steps include assessing performance across a range of nodes, threads per node, and ocean resolutions on Cori-KNL.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Spider silk MASP1 and MASP2 proteins as carbon fiber precursors

The objective of this project is to develop an unconventional non-petroleum based carbon fiber precursor which has the potential to be produced in high yield and quantities. Methods will be developed to produce pilot-scale quantities of fibers from spider silk proteins with mechanical properties at least 75% that of the natural dragline silk fibers in tensile strength and elongations of less than 5%. The precursor fibers will be converted to carbon fibers, with a goal of >250Ksi strength and 1-2% elongation. Cost analysis will be performed and the process optimized. Task 1: Subtask 1. Protein production: We exceeded the go/ no go milestone of 1.0g/L of one of the spider silk protein (MSp2) purified last FY and have now increased from 5L to 500L fermentations. We have made a series of changes to the purification protocol from the initial report last FY. These led to a reduction in the time needed for the purification and reduced the purification costs by nearly 90%. Subtask 2. Fiber spinning: The major focus has been to produce more material to send 24 fiber thread to ONRL. We are still developing the methodology to successfully spin 24 fiber yarns. This involves both the spinning dope solutions as well as the methods to keep the fibers from fusing during the post spin stretch. The second area of focus has been to standardize the spin dopes for making the fibers. We now know that the conductivity (indicative of salt remaining with the protein after purification) is an important factor in successful spinning as is the pH. We now know that we need to be below 600 uS conductivity and that the most effective pH is protein dependent. Subtask 3. Silkworm silk: We have found the transgenic silkworms made using gene replacement at the fibroin light chain instead of heavy chain as we did previously have a higher tensile strength. See figures below showing the curve for the top end of the cocoon fibers. This tensile strength is the same as the average for spider dragline silk. Task 2. Carbonization: The major accomplishment in the latter part of the work is that the ONRL group has successfully heated the spider silk protein fibers all the way up to 1700°C and produced a very competitive carbon fiber based on mechanical properties. Several important factors were discovered during these initial trials: 1) the ramp speed for increasing the temperature is critical; 2) maintaining tension on the fiber during the heating process because as it is heated it tends to expand; and 3) narrow temperature window in which stretching the fiber during heating leads to much better final materials. Task 3. Techno-Economic Methods: The techno-economic analysis was expanded to determine the relative cost of production with the bacterial production system compared to the transgenic alfalfa and goat production systems. The comparisons show two important things. For all systems the key factor in the final price is the amount of spider silk protein produced for whatever measure of volume or weight is used. Second alfalfa can be the cheapest but is subject to the possible regulatory control unless the US develops a more comprehensive approach to GMOs. The silkworm analysis was not completed due to a variety of confounding factors. The primary one was that if the production were shifted overseas then the cost would likely be nearly equivalent to current silk prices of $5-15/kg. However if concerns about the location of production is important then it would need to be done in the US and initial costs would be much higher but if the later scenario is utilized then the cost would be lowered but it was not possible to calculate exact costs.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Magnesium Diboride thin Films, multilayers, and coatings for SRF cavities

Superconducting radio frequency (SRF) cavities currently use low-temperature superconductor niobium, and the Nb SRF cavities have approached the performance levels predicted theoretically. Compared to Nb, MgB 2 becomes superconducting at a much higher temperature and promises a better RF performance in terms of higher quality factor Q and higher acceleration capability. An MgB 2 SRF technology can significantly reduce the operating costs of particle accelerators when these potentials are realized. This project aimed to advance the development of an MgB 2 SRF technology. It had two main objectives: (1) materials issues of MgB 2 thin films and multilayers related to their applications in SRF cavities; and (2) coating single-cell cavities for testing at RF frequencies. The key technical thrust of the project is the deposition of high quality clean MgB 2 films and coatings by the hybrid physical-chemical vapor deposition (HPCVD) technique, which was developed in my group. We have achieved technical progress in each of the two areas. For the first objective, we have confirmed that MgB 2 thin film coatings can be used to effectively enhance the vortex penetration field of an SRF cavity. A vortex is a normal region in the shape of spaghetti that threads through a superconductor. Its existence is due to an applied magnetic field that is greater than a so-called lower critical field, H c1 . Once a vortex enters the superconductor, its movement leads to loss. This has been shown to be the reason for an SRF cavity to break down. Thus, enhancing the magnetic field for a vortex to enter the superconductor that forms the SRF cavity has be a goal of intense research. To this end, Gurevich proposed that a coating of thin superconductor layer can impede the vortex entrance. In this project, we have done two important experiment to test this concept. One, we showed that the enhancement of H c1 can be achieved by using in both epitaxial and polycrystalline MgB 2 films. Although H c1 is low for bulk MgB 2 samples, about 600 Oe at 5 K, it increases with decreasing film thickness, reaching 1880 Oe when the film thickness is 100 nm. Two, we coated Nb ellipsoids with MgB 2 films to achieve an “inverse cavity” configuration, mimicking the coating of an actual RF cavity. Our results demonstrate that it is indeed possible to increase the vortex penetration field of a cavity by a substantial amount (~600 Oe) by coating it with a thin MgB 2 film. For the second objective, we modified the existing HPCVD system to be able to coat a 3.9 GHz SRF cavity, and using a stainless steel mock cavity showed that a uniform film with good superconducting property can be grown across the cavity interior. Further, we successfully deposited MgB 2 on Cu disc. The two results combined demonstrate that it is possible to coat Cu cavities with high quality MgB 2 films using HPCVD. MgB 2 coated Cu could open up a possibility of using SRF cavities at 20–25 K with cryocoolers.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Effects of Laser Etching on the Corrosion Susceptibility of SAVY 4000 and Hagan Containers

Since the late 1990’s, the Hagan container was used as the primary container for packaging of plutonium-bearing materials. The Hagan design consisted of a threaded closure, a Viton® ORing, a carbon-carbon filter, and a 304L stainless steel (SS) body. Over the years, Hagans have shown vulnerability in their design [1]. In 2008, The Department of Energy (DOE) issued DOE M 441.1-1, Nuclear Material Packaging Manual, which detailed an approach to obtain highconfidence in containers by including specific design requirements, material contents and an approach to determine life span from said contents, and surveillance techniques [2]. In response to both the vulnerability issues with the Hagan and DOE M 441.1-1, the SAVY 4000 container with its twist style closure, Viton® O-Ring, Fiberfrax-Gortex filter, and annealed 316L SS body, was designed as the replacement for Hagan containers, but only for a short term lifespan of 5 years [1]. However, both the Hagan and SAVY 4000 are being pushed to maintain a lifespan of 40 years. Therefore, proper confidence must be placed on each component of each container to last a minimum of 40 years. So far, the biggest concern found during surveillance of these containers is corrosion and the potential for failure by corrosion. One concern is that the containers fail due to stress corrosion cracking (SCC), especially around the weld between the collar and the body as welds leave residual stresses. One advantage the SAVY 4000 has is that the body is annealed, but its weld is still susceptible as it was welded after annealing [3, 4]. Moreover, 316L SS is known to have a higher pitting resistance (pits are a precursor to SCC and can also lead to extensive failure of the material), than 304L SS [4]. During recent surveillance activities, two SAVY 4000’s containing Solution Assay Instrument (SAI) solutions were opened. The SAI SAVY 4000’s contained plutonium (Pu) in 3M HCl solution in plastic volumetric flasks placed inside of polyethylene bags. Historically, a SAVY 4000 containing an SAI solution is packaged for 3 weeks, however, these particular containers were not reopened until 14 months later. When opened, brown-red corrosion product was found all over the inside of the container as shown in Figure 1.

36 MATERIALS SCIENCE↗
DOE OSTI2017

UPC++ Programmer’s Guide (v1.0 2017.9)

UPC++ is a C++11 library that provides Asynchronous Partitioned Global Address Space (APGAS) programming. It is designed for writing parallel programs that run efficiently and scale well on distributed-memory parallel computers. The APGAS model is single program, multiple-data (SPMD), with each separate thread of execution (referred to as a rank, a term borrowed from MPI) having access to local memory as it would in C++. However, APGAS also provides access to a global address space, which is allocated in shared segments that are distributed over the ranks. UPC++ provides numerous methods for accessing and using global memory. In UPC++, all operations that access remote memory are explicit, which encourages programmers to be aware of the cost of communication and data movement. Moreover, all remote-memory access operations are by default asynchronous, to enable programmers to write code that scales well even on hundreds of thousands of cores.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

UPC++ Programmer’s Guide, v1.0-2018.3.0

UPC++ is a C++11 library that provides Partitioned Global Address Space (PGAS) programming. It is designed for writing parallel programs that run efficiently and scale well on distributed-memory parallel computers. The PGAS model is single program, multiple-data (SPMD), with each separate thread of execution (referred to as a rank, a term borrowed from MPI) having access to local memory as it would in C++. However, PGAS also provides access to a global address space, which is allocated in shared segments that are distributed over the ranks. UPC++ provides numerous methods for accessing and using global memory. In UPC++, all operations that access remote memory are explicit, which encourages programmers to be aware of the cost of communication and data movement. Moreover, all remote-memory access operations are by default asynchronous, to enable programmers to write code that scales well even on hundreds of thousands of cores.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2017

XPRESS: eXascale PRogramming Environment and System Software, Final Report

The University of Oregon (UO) was a partner in the XPRESS project together with Sandia National Laboratories (SNL), Indiana University (IU), Lawrence Berkeley National Laboratory (LBL), Louisiana State University (LSU), Oak Ridge National Laboratory (ORNL), University of Houston (UH), and University of North Carolina (RENCI). UO's objective in the project was to develop "APEX (Asynchronous Performance Environment for eXascale)": performance measurement, analysis, feedback and control infrastructure to asynchronous tasking runtimes, specifically HPX (LSU) and HPX-5 (IU). During the project period, our efforts focused on the need to measure complex tasking models where the traditional instrumentation methods would not work due to an absent/meaningless call-path context and runtime control of task pre-emption and resumption, usually on a different operating system thread. In addition to the challenges of performance measurement, we developed a framework to provide information from all levels of the stack (hardware, operating system, runtime, application) to a feedback & control mechanism for controlling concurrency, task granularity, networking parameters, and other aspects of execution in order to improve execution performance, throughput and/or efficiency. UO demonstrated these developments on leading edge HPC machines at large scale, including a 2017 Gordon Bell submission in which APEX was used to optimize key bottlenecks in an astrophysics application. The following final report summarizes our accomplishments during the XPRESS project.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2018

Targeting Maturation and Quality Control of Photosynthetic Membrane Proteins

Plsp1 is a type I signal peptidase that is responsible for removing the targeting signal peptide from passenger proteins upon their delivery to the thylakoid lumen. Plsp1 is itself a resident of the thylakoid membrane, with a single membrane anchor and the catalytic domain facing the lumen. Work to uncover the targeting mechanism for this protein has been underway in the Inoue lab from the previous DOE funding period has established that Plsp1 is targeted at the thylakoid by the Sec1 translocase, and that it passes through a high molecular weight intermediate in the stroma en route to the thylakoid membrane. During this funding period we have demonstrated by MS/MS of immunoprecipitated samples that the high molecular weight complex containing Plsp1 in the stroma contains primarily the α1 and β1 forms of Cpn60 in approximately equal amounts. Mixing experiments with overexpressed purified proteins have reproduced the Cpn60/Plsp1 complex. Surprisingly, the co-chaperonins Cpn10 and Cpn20 were not detected in the immunoprecipitated sample, even though they are able to bind to the Cpn60/Plsp1 complex formed in mixing experiments. We have further confirmed that the addition of purified stromal cpSecA1 results in a decrease in the amount of Plsp1 successfully incorporated into the thylakoid membrane. We are currently working on experiments to describe the conditions for the handoff between Cpn60 and cpSec1 in the stroma prior to membrane targeting. The structure of Plsp1 can be inferred by threading its sequence onto the structure of its E. coli homologue LepB to contain a single membrane anchor followed by a soluble structure consisting of ten β strands. In the last DOE funding period it was determined that the transmembrane domain not only acts as the membrane anchor, but probably mediates the interaction with cpSecA1. We have now determined that the binding to Cpn60 is likely mediated by β strands 1 and 2. What is the mechanism and significance of oxidative folding of Plsp1? It was found during the last DOE funding period that Plsp1 purified after overexpression in E. coli loses its peptidase activity upon reduction of its conserved cysteines. We have now determined that Plsp1 undergoes a measurable conformational change upon reduction, both by monitoring susceptibility to protease and by native tryptophan fluorescence. We have also shown that Plsp1 is at least partly, and likely completely, oxidized in the thylakoid lumen. While these results were not unexpected, experiments on Plsp1 in vivo were completely surprising. We have known for years (from work conducted with prior DOE funding) that a Plsp1 knockout is embryo lethal. Accordingly, given that reduction of the isolated protein inactivates it, we expected that plants in which one or both of the cysteine pair were mutated would also lead to a severe mutant phenotype. This was not observed, and in fact, these mutants complemented fully the plsp1 plants. This lead to the hypothesis that either association with an interacting protein or with the membrane preserves Plsp1structure even when the disulfides are reduced. Work performed in the last DOE funding cycle revealed that Pgrl1, a protein reportedly involved in cyclic electron flow, interacts stably with Plsp1. However, the Plsp1 cysteine-less mutants are still able to compliment the plsp1 mutant even in the pgrl1 knockout mutant background. We have also found that in vitro activity of Plsl1 is not abolished by reduction in thylakoids that have been permeabilized by low concentrations of detergent, whereas the activity of fully extracted protein is. This points to membrane association as the condition important to activity, and by extension, structure preservation. We are presently working to isolate Plsp1 in a lipid nanodisk to test this hypothesis.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2018

DARMA-Kokkos Data and Execution Interoperability WBS 2.3.1.04 Milestone 16 (ECP Milestone Report)

DARMA (Distributed Asynchronous Resilient Models for Applications) is a runtime library supporting the Sandia ATDM (Advanced Technology Development and Mitigation) program. The main application drivers fall within the ECP milestone 2.2.5.03 ADNN03-ASC ATDM SNL Application, which includes applications that require load balancing and asynchronous communication for high performance. The DARMA runtime infrastructure has been modified to be compatible with Kokkos/OpenMP parallelization within tasks, which is a critical requirement for high performance for the Sandia ATDM apps. DARMA development has occurred in parallel with a verification milestone for ATDM in FY18. For FY19, DARMA should impact ATDM by enabling dynamic load balancing and communication through only incremental changes to the existing verified MPI codes. DARMA can now support the intra-kernel thread parallelization in the parent MPI apps, allowing DARMA to be easily added without rewriting individual math kernels. The results presented here demonstrate the DARMA results for an MPI mini-app.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2019

Program Fuzzing on High Performance Computing Resources

American Fuzzy Lop (AFL) is an evolutionary fuzzer that is strategically implemented as a tool for discovering bugs in software during vulnerability research. This work seeks to understand how to best implement AFL on the High-Performance Computing resources available on the unclassified network at Sandia National Laboratories. We investigate various methods of executing AFL, requesting varying numbers of tasks on single compute nodes with 36 physical cores and 72 total threads. A Python script called Blue Claw is presented as an automated testbed generator tool to assist in the tedious process of creating and executing experiments of any scale and duration.

97 MATHEMATICS AND COMPUTING↗