LoGPC: Modeling Network Contention in Message-Passing Programs

In many real applications, for example those with frequent and irregular communication patterns or those using large messages, network contention and contention for message processing resources can be a significant part of the total execution time. This paper presents a new cost model, called LoGPC, that extends the LogP [9] and LogGP [4] models to account for the impact of network contention and network interface DMA behavior on the performance of message-passing programs. We validate LoGPC by analyzing three applications implemented with Active Messages [11, 18] on the MIT Alewife multiprocessor. Our analysis shows that network contention accounts for up to 50% of the total execution time. In addition, we show that the impact of communication locality on the communication costs is at most a factor of two on Alewife. Finally, we use the model to identify tradeoffs between synchronous and asynchronous message passing styles. 1 Introduction Users of parallel machines need good performa..

The technopolitics of security: agency, temporality, sovereignty

This introduction to the special issue on ‘the technopolitics of security’ outlines key concepts and engages debates pertaining to the relationship between techno-materiality, security governance and struggles over sovereignty. ‘Technopolitics’ refers to the strategic practice of designing and using technologies to enact political goals, producing hybrid forms of power that combine cultural, institutional and technological dimensions. These technopolitical practices give rise to new forms of agency, producing effects unintended by their designers that may alter logics of political contestation and allow technologies to be reappropriated for different political purposes. To illustrate the distributed forms of agency and contingent encounters that the technopolitics approach evokes, the article develops three key aspects of technopolitics in its relationship to security governance: (1) an understanding of agency as distributed between human and non-human actors, but also asymmetric in that human intentionality plays an assembling role that is frequently overrun by the unintended effects; (2) the temporal horizons of imagination and action over which technopolitical interventions unfold, identifying the importance of logics of anticipation and eventization; and (3) the relationship between technopolitics and sovereignty, arguing that it encourages a decentred and materialized understanding of how claims to sovereignty are made and contested

SUDS : automatic parallelization for raw processors

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.Includes bibliographical references (p. 177-181).A computer can never be too fast or too cheap. Computer systems pervade nearly every aspect of science, engineering, communications and commerce because they perform certain tasks at rates unachievable by any other kind of system built by humans. A computer system's throughput, however, is constrained by that system's ability to find concurrency. Given a particular target work load the computer architect's role is to design mechanisms to find and exploit the available concurrency in that work load. This thesis describes SUDS (Software Un-Do System), a compiler and runtime system that can automatically find and exploit the available concurrency of scalar operations in imperative programs with arbitrary unstructured and unpredictable control flow. The core compiler transformation that enables this is scalar queue conversion. Scalar queue conversion makes scalar renaming an explicit operation through a process similar to closure conversion, a technique traditionally used to compile functional languages. The scalar queue conversion compiler transformation is speculative, in the sense that it may introduce dynamic memory allocation operations into code that would not otherwise dynamically allocate memory. Thus, SUDS also includes a transactional runtime system that periodically checkpoints machine state, executes code speculatively, checks if the speculative execution produced results consistent with the original sequential program semantics, and then either commits or rolls back the speculative execution path. In addition to safely running scalar queue converted code, the SUDS runtime system safely permits threads to speculatively run in parallel and concurrently issue memory operations, even when the compiler is unable to prove that the reordered memory operations will always produce correct results.(cont.) Using this combination of compile time and runtime techniques, SUDS can find concurrency in programs where previous compiler based renaming techniques fail because the programs contain unstructured loops, and where Tomasulo's algorithm fails because it sequentializes mispredicted branches. Indeed, we describe three application programs, with unstructured control flow, where the prototype SUDS system, running in software on a Raw microprocessor, achieves speedups equivalent to, or better than, an idealized, and unrealizable, model of a hardware implementation of Tomasulo's algorithm.by Matthew Ian Frank.Ph.D

System Support for Implicitly Parallel Programming

Coordinated Science Laboratory was formerly known as Control Systems Laborator

LoPC-- modeling contention in parallel algorithms

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1998.Includes bibliographical references (p. 43-44).by Matthew Frank.M.S

Field testing a novel high residence positioning system for monitoring the fine‐scale movements of aquatic organisms

1. Acoustic telemetry is an important tool for studying the behaviour of aquatic organisms in the wild. 2. VEMCO high residence (HR) tags and receivers are a recent introduction in the field of acoustic telemetry and can be paired with existing algorithms (e.g. VEMCO positioning system [VPS]) to obtain high‐resolution two‐dimensional positioning data. 3. Here, we present results of the first documented field test of a VPS composed of HR receivers (hereafter, HR‐VPS). We performed a series of stationary and moving trials with HR tags (mean HR transmission period = 1.5 s) to evaluate the precision, accuracy and temporal capabilities of this positioning technology. In addition, we present a sample of data obtained for five European perch Perca fluviatilis implanted with HR tags (mean HR transmission period = 4 s) to illustrate how this technology can estimate the fine‐scale behaviour of aquatic animals. 4. Accuracy and precision estimates (median [5th–95th percentile]) of HR‐VPS positions for all stationary trials were 5.6 m (4.2–10.8 m) and 0.1 m (0.02–0.07 m), respectively, and depended on the location of tags within the receiver array. In moving tests, tracks generated by HR‐VPS closely mimicked those produced by a handheld GPS held over the tag, but these differed in location by an average of ≈9 m. 5. We found that estimates of animal speed and distance travelled for perch declined when positional data for acoustically tagged perch were thinned to mimic longer transmission periods. These data also revealed a trade‐off between capturing real nonlinear animal movements and the inclusion of positioning error. 6. Our results suggested that HR‐VPS can provide more representative estimates of movement metrics and offer an advancement for studying fine‐scale movements of aquatic organisms, but high‐precision survey techniques may be needed to test these systems

Scalar Queue Conversion: Dynamic Single Assignment for Concurrent Scheduling

Coordinated Science Laboratory was formerly known as Control Systems LaboratoryNSFDARPAIndustrial Technology Research Institute/Raw Project CollaborationElectrical and Computer Engineering Department at the University of Illinoi

Health facility and skilled birth deliveries among poor women with Jamkesmas health insurance in Indonesia: a mixed-methods study

BACKGROUND: The growing momentum for quality and affordable health care for all has given rise to the recent global universal health coverage (UHC) movement. As part of Indonesia’s strategy to achieve the goal of UHC, large investments have been made to increase health access for the poor, resulting in the implementation of various health insurance schemes targeted towards the poor and near-poor, including the Jamkesmas program. In the backdrop of Indonesia’s aspiration to reach UHC is the high rate of maternal mortality that disproportionally affects poor women. The objective of this study was to evaluate the association of health facility and skilled birth deliveries among poor women with and without Jamkesmas and explore perceived barriers to health insurance membership and maternal health service utilization. METHODS: We used a mixed-methods design. Utilizing data from the 2012 Indonesian Demographic and Health Survey (n = 45,607), secondary analysis using propensity score matching was performed on key outcomes of interest: health facility delivery (HFD) and skilled birth delivery (SBD). In-depth interviews (n = 51) were conducted in the provinces of Jakarta and Banten among poor women, midwives, and government representatives. Thematic framework analysis was performed on qualitative data to explore perceived barriers. RESULTS: In 2012, 63.0% of women did not have health insurance; 19.1% had Jamkesmas. Poor women with Jamkesmas were 19% (OR = 1.19 [1.03–1.37]) more likely to have HFD and 17% (OR = 1.17 [1.01–1.35]) more likely to have SBD compared to poor women without insurance. Qualitative interviews highlighted key issues, including: lack of proper documentation for health insurance registration; the preference of pregnant women to deliver in their parents’ village; the use of traditional birth attendants; distance to health facilities; shortage of qualified health providers; overcrowded health facilities; and lack of health facility accreditation. CONCLUSION: Poor women with Jamkesmas membership had a modest increase in HFD and SBD. These findings are consistent with economic theory that health insurance coverage can reduce financial barriers to care and increase service uptake. However, factors such as socio-cultural beliefs, accessibility, and quality of care are important elements that need to be addressed as part of the national UHC agenda to improve maternal health services in Indonesia

PaCo: Probability-based Path Confidence Prediction

Coordinated Science Laboratory was formerly known as Control Systems LaboratoryNational Science Foundation / CCR-042971Gigascale Systems Research Cente

Impact of Sleep and Circadian Disruption on Energy Balance and Diabetes: A Summary of Workshop Discussions

A workshop was held at the National Institute for Diabetes and Digestive and Kidney Diseases with a focus on the impact of sleep and circadian disruption on energy balance and diabetes. The workshop identified a number of key principles for research in this area and a number of specific opportunities. Studies in this area would be facilitated by active collaboration between investigators in sleep/circadian research and investigators in metabolism/diabetes. There is a need to translate the elegant findings from basic research into improving the metabolic health of the American public. There is also a need for investigators studying the impact of sleep/circadian disruption in humans to move beyond measurements of insulin and glucose and conduct more in-depth phenotyping. There is also a need for the assessments of sleep and circadian rhythms as well as assessments for sleep-disordered breathing to be incorporated into all ongoing cohort studies related to diabetes risk. Studies in humans need to complement the elegant short-term laboratory-based human studies of simulated short sleep and shift work etc. with studies in subjects in the general population with these disorders. It is conceivable that chronic adaptations occur, and if so, the mechanisms by which they occur needs to be identified and understood. Particular areas of opportunity that are ready for translation are studies to address whether CPAP treatment of patients with pre-diabetes and obstructive sleep apnea (OSA) prevents or delays the onset of diabetes and whether temporal restricted feeding has the same impact on obesity rates in humans as it does in mice