General hardware multicasting for fine-grained message-passing architectures

Manycore architectures are increasingly favouring message-passing or partitioned global address spaces (PGAS) over cache coherency for reasons of power efficiency and scalability. However, in the absence of cache coherency, there can be a lack of hardware support for one-to-many communication patterns, which are prevalent in someapplication domains. To address this, we present new hardware primitives for multicast communication in rack-scale manycore systems. These primitives guarantee delivery to both colocated and distributed destinations, and can capture large unstructured communication patterns precisely. As a result, reliable multicast transfers among any number of software tasks, connected in any topology, can be fully offloaded to hardware. We implement the new primitives in a research platform consisting of 50K RISC-V threads distributed over 48 FPGAs, and demonstrate significant performance benefits on a range of applications expressed using a high-level vertex-centric programming model

Using Runahead Execution to Hide Memory Latency in High Level Synthesis

Reads and writes to global data in off-chip RAM can limit the performance achieved with HLS tools, as each access takes multiple cycles and usually blocks progress in the application state machine. This can be combated by using data prefetchers, which hide access time by predicting the next memory access and loading it into a cache before it's required. Unfortunately, current prefetchers are only useful for memory accesses with known regular patterns, such as walking arrays, and are ineffective for those that use irregular patterns over application-specific data structures. In this work, we demonstrate prefetchers that are tailor-made for applications, even if they have irregular memory accesses. This is achieved through program slicing, a static analysis technique that extracts the memory structure of the input code and automatically constructs an application-specific prefetcher. Both our analysis and tool are fully automated and implemented as a new compiler flag in LegUp, an open source HLS tool. In this work we create a theoretical model showing that speedup must be between 1x and 2x, we also evaluate five benchmarks, achieving an average speedup of 1.38x with an average resource overhead of 1.15x

Injecting FPGA Configuration Faults in Parallel

When using SRAM-based FPGA devices in safety critical applications testing against bitflips in the device configuration memory is essential. Often such tests are achieved by corrupting configuration memory bits of a running device, but this has many scalability, reliability, and flexibility challenges. In this paper, we present a framework and a concrete implementation of a parallel fault injection cluster that addresses these challenges. Scalability is addressed by using multiple identical FPGA devices, each testing a different region in parallel. Reliability is addressed by using reconfigurable system-on-chip devices, that are isolated from each other. Flexibility is addressed by using a pending commit structure, that continually checkpoints the overall experiment and allows elastic scaling. We test and showcase our approach by exhaustively flipping every bit in the configuration memory of the CHStone benchmark suite and a VivadoHLS generated k-means clustering image processing application. Our results show that: linear scaling is possible as the number of devices increases; the majority of error inducing bitflips in the k-means application do not significantly impact the output; and that the Xilinx Essential bits tool may miss some bits that can induce errors

Sustained Magnetorotational Turbulence in Local Simulations of Stratified Disks with Zero Net Magnetic Flux

We examine the effects of density stratification on magnetohydrodynamic turbulence driven by the magnetorotational instability in local simulations that adopt the shearing box approximation. Our primary result is that, even in the absence of explicit dissipation, the addition of vertical gravity leads to convergence in the turbulent energy densities and stresses as the resolution increases, contrary to results for zero net flux, unstratified boxes. The ratio of total stress to midplane pressure has a mean of ~0.01, although there can be significant fluctuations on long (>~50 orbit) timescales. We find that the time averaged stresses are largely insensitive to both the radial or vertical aspect ratio of our simulation domain. For simulations with explicit dissipation, we find that stratification extends the range of Reynolds and magnetic Prandtl numbers for which turbulence is sustained. Confirming the results of previous studies, we find oscillations in the large scale toroidal field with periods of ~10 orbits and describe the dynamo process that underlies these cycles.Comment: 13 pages, 18 figures, submitted to Ap

Design fundamentals of mentoring programs for pharmacy professionals (Part 2): Considerations for mentors and mentees

Developing a mentoring program is multifactorial, and organizations developing such programs must be reflective in considering their own organizational culture to determine the goals and outcomes assessment of a mentoring program that aligns with the organization's mission and values. Part 1 of this series of papers on devising mentoring programs for pharmacy professionals paid mind to their structure, logistical concerns, and basic design consideration. Designing a program, though, cannot be successful without consideration of the people involved, and the very human process that is mentoring and being mentored. This Part 2 paper takes into account the human needs of mentors and mentees, both independently and as pairs or groups involved in a potentially intimate and caring relationship that lasts anywhere from several months, to potentially a lifetime should the relationship be successful. As such, this commentary pays careful attention to the evolving roles each person plays and what this means to administrators overseeing or assessing the results and implications from such a program so as to strive for maximum organizational effectiveness for employing institutions and self-actualization for persons involved in the program

Termination detection for fine-grained message-passing architectures

Barrier primitives provided by standard parallel programming APIs are the primary means by which applications implement global synchronisation. Typically these primitives are fully-committed to synchronisation in the sense that, once a barrier is entered, synchronisation is the only way out. For message-passing applications, this raises the question of what happens when a message arrives at a thread that already resides in a barrier. Without a satisfactory answer, barriers do not interact with message-passing in any useful way. In this paper, we propose a new refutable barrier primitive that combines with message-passing to form a simple, expressive, efficient, well-defined API. It has a clear semantics based on termination detection, and supports the development of both globally-synchronous and asynchronous parallel applications. To evaluate the new primitive, we implement it in a prototype large-scale message-passing machine with 49,152 RISC-V threads distributed over 48 FPGAs. We show that hardware support for the primitive leads to a highly-efficient implementation, capable of synchronisation rates that are an order-of-magnitude higher than what is achievable in software. Using the primitive, we implement synchronous and asynchronous versions of a range of applications, observing that each version can have significant advantages over the other, depending on the application. Therefore, a barrier primitive supporting both styles can greatly assist the development of parallel programs.Funded by EPSRC grant EP/N031768/1 (POETS project

Are School Absences Correlated with Influenza Surveillance Data in England? Results from Decipher My Data-A Research Project Conducted through Scientific Engagement with Schools.

BACKGROUND: School aged children are a key link in the transmission of influenza. Most cases have little or no interaction with health services and are therefore missed by the majority of existing surveillance systems. As part of a public engagement with science project, this study aimed to establish a web-based system for the collection of routine school absence data and determine if school absence prevalence was correlated with established surveillance measures for circulating influenza. METHODS: We collected data for two influenza seasons (2011/12 and 2012/13). The primary outcome was daily school absence prevalence (weighted to make it nationally representative) for children aged 11 to 16. School absence prevalence was triangulated graphically and through univariable linear regression to Royal College of General Practitioners (RCGP) influenza like illness (ILI) episode incidence rate, national microbiological surveillance data on the proportion of samples positive for influenza (A+B) and with Rhinovirus, RSV and laboratory confirmed cases of Norovirus. RESULTS: 27 schools submitted data over two respiratory seasons. During the first season, levels of influenza measured by school absence prevalence and established surveillance were low. In the 2012/13 season, a peak of school absence prevalence occurred in week 51, and week 1 in RCGP ILI surveillance data. Linear regression showed a strong association between the school absence prevalence and RCGP ILI (All ages, and 5-14 year olds), laboratory confirmed cases of influenza A & B, and weak evidence for a linear association with Rhinovirus and Norovirus. INTERPRETATION: This study provides initial evidence for using routine school illness absence prevalence as a novel tool for influenza surveillance. The network of web-based data collection platforms we established through active engagement provides an innovative model of conducting scientific research and could be used for a wide range of infectious disease studies in the future

Design fundamentals of mentoring programs for pharmacy professionals (Part 1): Considerations for organizations

Mentoring programs have been offered by organizations within and outside of healthcare for years. This commentary examines the literature under the prism of design fundamentals for these programs, drawing particular considerations for schemes aimed at pharmacy professionals. The central argument presented is that mentoring can be used as a vehicle to support pharmacists to learn from others and each other, to reinforce and own their professional identity so that the uniqueness of the pharmacy profession is established within a global health landscape of constant change. In this Part 1 of a series of papers, a wealth of literature, theories, and evidence are presented aiming to inform the general structure and logistical considerations for both in-person and distance mentoring programs

ANZAED eating disorder treatment principles and general clinical practice and training standards

Introduction: Eating disorders are complex to manage, and there is limited guidance around the depth and breadth of knowledge, skills and experience required by treatment providers. The Australia & New Zealand Academy for Eating Disorders (ANZAED) convened an expert group of eating disorder researchers and clinicians to define the clinical practice and training standards recommended for mental health professionals and dietitians providing treatment for individuals with an eating disorder. General principles and clinical practice standards were first developed, after which separate mental health professional and dietitian standards were drafted and collated by the appropriate members of the expert group. The subsequent review process included four stages of consultation and document revision: (1) expert reviewers; (2) a face-to-face consultation workshop attended by approximately 100 health professionals working within the sector; (3) an extensive open access online consultation process; and (4) consultation with key professional and consumer/carer stakeholder organisations. Recommendations: The resulting paper outlines and describes the following eight eating disorder treatment principles: (1) early intervention is essential; (2) co-ordination of services is fundamental to all service models; (3) services must be evidence-based; (4) involvement of significant others in service provision is highly desirable; (5) a personalised treatment approach is required for all patients; (6) education and/or psychoeducation is included in all interventions; (7) multidisciplinary care is required and (8) a skilled workforce is necessary. Seven general clinical practice standards are also discussed, including: (1) diagnosis and assessment; (2) the multidisciplinary care team; (3) a positive therapeutic alliance; (4) knowledge of evidence-based treatment; (5) knowledge of levels of care; (6) relapse prevention; and (7) professional responsibility. Conclusions: These principles and standards provide guidance to professional training programs and service providers on the development of knowledge required as a foundation on which to build competent practice in the eating disorder field. Implementing these standards aims to bring treatment closer to best practice, and consequently improve treatment outcomes, reduce financial cost to patients and services and improve patient quality of life