A cross-stack, network-centric architectural design for next-generation datacenters

This thesis proposes a full-stack, cross-layer datacenter architecture based on in-network computing and near-memory processing paradigms. The proposed datacenter architecture is built atop two principles: (1) utilizing commodity, off-the-shelf hardware (i.e., processor, DRAM, and network devices) with minimal changes to their architecture, and (2) providing a standard interface to the programmers for using the novel hardware. More specifically, the proposed datacenter architecture enables a smart network adapter to collectively compress/decompress data exchange between distributed DNN training nodes and assist the operating system in performing aggressive processor power management. It also deploys specialized memory modules in the servers, capable of performing general-purpose computation and network connectivity. This thesis unlocks the potentials of hardware and operating system co-design in architecting application-transparent, near-data processing hardware for improving datacenter's performance, energy efficiency, and scalability. We evaluate the proposed datacenter architecture using a combination of full-system simulation, FPGA prototyping, and real-system experiments

Galley: A New Parallel File System for Parallel Applications

Most current multiprocessor file systems are designed to use multiple disks in parallel, using the high aggregate bandwidth to meet the growing I/O requirements of parallel scientific applications. Most multiprocessor file systems provide applications with a conventional Unix-like interface, allowing the application to access those multiple disks transparently. This interface conceals the parallelism within the file system, increasing the ease of programmability, but making it difficult or impossible for sophisticated application and library programmers to use knowledge about their I/O to exploit that parallelism. In addition to providing an insufficient interface, most current multiprocessor file systems are optimized for a different workload than they are being asked to support. In this work we examine current multiprocessor file systems, as well as how those file systems are used by scientific applications. Contrary to the expectations of the designers of current parallel file systems, the workloads on those systems are dominated by requests to read and write small pieces of data. Furthermore, rather than being accessed sequentially and contiguously, as in uniprocessor and supercomputer workloads, files in multiprocessor file systems are accessed in regular, structured, but non-contiguous patterns. Based on our observations of multiprocessor workloads, we have designed Galley, a new parallel file system that is intended to efficiently support realistic scientific multiprocessor workloads. In this work, we introduce Galley and discuss its design and implementation. We describe Galley\u27s new three-dimensional file structure and discuss how that structure can be used by parallel applications to achieve higher performance. We introduce several new data-access interfaces, which allow applications to explicitly describe the regular access patterns we found to be common in parallel file system workloads. We show how these new interfaces allow parallel applications to achieve tremendous increases in I/O performance. Finally, we discuss how Galley\u27s new file structure and data-access interfaces can be useful in practice

Bridging a Gap Between Research and Production: Contributions to Scheduling and Simulation

Large scale distributed computing infrastructures (e.g., data centers, grids, or clouds) are used by scientists from various domains to produce outstanding research results, such as the discovery of the Higgs Boson in High Energy Physics. These infrastructures are also studied by Computer Scientists to produce their own set of scientific results. Ideally, a virtuous circle should exist between Domain and Computer Scientists: the former raising challenges that could be addressed by the latter. Unfortunately, in many occasions, a gap exists that prevents such an ideal and fostering collaboration. This habilitation covers research works conducted in the fields of scheduling and simulation that contribute to the filling of this gap. It discusses the necessary conditions to achieve this goal and details concrete initiatives in this endeavor

High-Performance Modelling and Simulation for Big Data Applications

This open access book was prepared as a Final Publication of the COST Action IC1406 “High-Performance Modelling and Simulation for Big Data Applications (cHiPSet)“ project. Long considered important pillars of the scientific method, Modelling and Simulation have evolved from traditional discrete numerical methods to complex data-intensive continuous analytical optimisations. Resolution, scale, and accuracy have become essential to predict and analyse natural and complex systems in science and engineering. When their level of abstraction raises to have a better discernment of the domain at hand, their representation gets increasingly demanding for computational and data resources. On the other hand, High Performance Computing typically entails the effective use of parallel and distributed processing units coupled with efficient storage, communication and visualisation systems to underpin complex data-intensive applications in distinct scientific and technical domains. It is then arguably required to have a seamless interaction of High Performance Computing with Modelling and Simulation in order to store, compute, analyse, and visualise large data sets in science and engineering. Funded by the European Commission, cHiPSet has provided a dynamic trans-European forum for their members and distinguished guests to openly discuss novel perspectives and topics of interests for these two communities. This cHiPSet compendium presents a set of selected case studies related to healthcare, biological data, computational advertising, multimedia, finance, bioinformatics, and telecommunications

Proceedings, MSVSCC 2015

The Virginia Modeling, Analysis and Simulation Center (VMASC) of Old Dominion University hosted the 2015 Modeling, Simulation, & Visualization Student capstone Conference on April 16th. The Capstone Conference features students in Modeling and Simulation, undergraduates and graduate degree programs, and fields from many colleges and/or universities. Students present their research to an audience of fellow students, faculty, judges, and other distinguished guests. For the students, these presentations afford them the opportunity to impart their innovative research to members of the M&S community from academic, industry, and government backgrounds. Also participating in the conference are faculty and judges who have volunteered their time to impart direct support to their students’ research, facilitate the various conference tracks, serve as judges for each of the tracks, and provide overall assistance to this conference. 2015 marks the ninth year of the VMASC Capstone Conference for Modeling, Simulation and Visualization. This year our conference attracted a number of fine student written papers and presentations, resulting in a total of 51 research works that were presented. This year’s conference had record attendance thanks to the support from the various different departments at Old Dominion University, other local Universities, and the United States Military Academy, at West Point. We greatly appreciated all of the work and energy that has gone into this year’s conference, it truly was a highly collaborative effort that has resulted in a very successful symposium for the M&S community and all of those involved. Below you will find a brief summary of the best papers and best presentations with some simple statistics of the overall conference contribution. Followed by that is a table of contents that breaks down by conference track category with a copy of each included body of work. Thank you again for your time and your contribution as this conference is designed to continuously evolve and adapt to better suit the authors and M&S supporters. Dr.Yuzhong Shen Graduate Program Director, MSVE Capstone Conference Chair John ShullGraduate Student, MSVE Capstone Conference Student Chai

High-Performance Modelling and Simulation for Big Data Applications

This open access book was prepared as a Final Publication of the COST Action IC1406 “High-Performance Modelling and Simulation for Big Data Applications (cHiPSet)“ project. Long considered important pillars of the scientific method, Modelling and Simulation have evolved from traditional discrete numerical methods to complex data-intensive continuous analytical optimisations. Resolution, scale, and accuracy have become essential to predict and analyse natural and complex systems in science and engineering. When their level of abstraction raises to have a better discernment of the domain at hand, their representation gets increasingly demanding for computational and data resources. On the other hand, High Performance Computing typically entails the effective use of parallel and distributed processing units coupled with efficient storage, communication and visualisation systems to underpin complex data-intensive applications in distinct scientific and technical domains. It is then arguably required to have a seamless interaction of High Performance Computing with Modelling and Simulation in order to store, compute, analyse, and visualise large data sets in science and engineering. Funded by the European Commission, cHiPSet has provided a dynamic trans-European forum for their members and distinguished guests to openly discuss novel perspectives and topics of interests for these two communities. This cHiPSet compendium presents a set of selected case studies related to healthcare, biological data, computational advertising, multimedia, finance, bioinformatics, and telecommunications

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Cross-sectoral hybridization as a strategy to turn institutional voids into opportunity spaces

Organizations that aim at delivering essential goods and services to low-income populations a the base of the pyramid increasingly blend the social welfare and the commercial logics in an effort to create financially sustainable solutions to social problems. Scholars have portrayed these cross-sectoral hybrid organizations as particularly agentic and resilient in institutionally complex settings, highlighting their ability to turn institutional voids into opportunity spaces. At the same time, the reconciliation of two antagonistic goals, namely poverty alleviation and financial value creation, as well as the multiple institutional voids that hybrid organizations face at the base of the pyramid (BoP) expose them to severe tensions. By investigating eight hybrid organizations in four countries, namely Colombia, Mexico, Kenya and South Africa, the present study contributes to a better understanding of cross-sectoral hybrid organizations in BoP settings in two ways. First, it shows that hybrid organizations not only face tensions between sector logics, but also between formal and informal, as well as between “Western-style” and “local style” strategic action fields. In settings which do not effectively provide guidance on the prioritization of social vs. financial objectives, these institutional voids manifest as tensions over goals and tensions over means in hybrid organizations. Second, the study sheds light on how field-level dynamics influence the ability of hybrid organizations to strategically employ factors that spur legitimacy advantages in an effort to turn institutional voids into opportunity spaces. Two different scenarios have been identified. One scenario refers to Colombia, Mexico and Kenya, which have been classified as fields that don’t effectively enforce a dominant sector logic concerning the legitimate way that health services should be provided to low-income populations. The present study has shown that in such fields, an organization’s logic of origin as well as the personal background of founders are factors that may spur legitimacy advantages in hybrid organizations. In effect, organizations which strategically employ these factors can select more freely from competing logics and ultimately overcome the prevailing tensions. This resonates with previous research, which has suggested that in fields with a dominant logic, hybrid organizations may take advantage of legitimacy advantages if their logic of origin corresponds to the dominant logic at the field level (Pache and Santos, 2012). However, the present study suggests that the factors leading to legitimacy advantages are more complex in fields with no effective dominant logic regarding social service provision. Here, the dominant logics among funding organizations, possible legitimacy spill-over effects from other market players, as well as the specifications of the commercial and the social welfare logics become important sources of possible legitimacy advantages. However, the study suggests that an organization’s ability to employ them strategically is dependent on their time of founding and their size. In addition to these findings, the study also provides insights on cross-sectoral hybridization in fields with a weakly enforced dominant logic, which is the second scenario that has been identified in South Africa. In particular, the study suggests that in such settings, hybrid organizations are more restricted to freely draw from competing logics, given that they face effective, normative imperatives about the goals they should pursue. However, the empirical investigation also indicates that an organization’s resource dependence structure is more influential than the encountered normative claims of audiences in health fields at the BoP. Further research is needed to refine these insights and explore cross-sectoral hybridization in social service provision fields in contexts of a weakly enforced dominant logic. Based on these findings, the author derives a range of practical recommendations that may themselves be interpreted as paradoxical. As the empirical study suggests, blended value creating hybrid organizations in Colombia, Mexico and Kenya currently face legitimacy advantages when originating from a commercial origin. The researcher is thus, on the one hand, inclined to recommend them to position themselves as commercially oriented organizations as to take advantage of the legitimacy advantages that the commercial logic currently entails. On the other hand, she cautions actors in the field of blended value creation, particularly funding entities, not to neglect the actual role of nonprofit organizations. The establishment of (health) markets that provide low-income populations in developing and emerging economies with affordable, high-quality products and services is likely to require significant unprofitable efforts. Finally, hybrid organizations in South Africa need to be more careful when adopting structures or practices from the commercial logic given the low legitimacy that this logic has in the health market at the BoP. There, organizations need to thoroughly analyze the institutional claims in the specific context of post-Apartheid South Africa