A Graph-Partition-Based Scheduling Policy for Heterogeneous Architectures

In order to improve system performance efficiently, a number of systems choose to equip multi-core and many-core processors (such as GPUs). Due to their discrete memory these heterogeneous architectures comprise a distributed system within a computer. A data-flow programming model is attractive in this setting for its ease of expressing concurrency. Programmers only need to define task dependencies without considering how to schedule them on the hardware. However, mapping the resulting task graph onto hardware efficiently remains a challenge. In this paper, we propose a graph-partition scheduling policy for mapping data-flow workloads to heterogeneous hardware. According to our experiments, our graph-partition-based scheduling achieves comparable performance to conventional queue-base approaches.Comment: Presented at DATE Friday Workshop on Heterogeneous Architectures and Design Methods for Embedded Image Systems (HIS 2015) (arXiv:1502.07241

Neverlast: Towards the Design and Implementation of the NVM-based Everlasting Operating System

Novel non-volatile memory (NVM) technologies allow for the efficient implementation of \u27\u27intermittently-powered\u27\u27 smart dust and edge computing systems in a previously unfamiliar way. Operating with rough environmental conditions where power-supply failures occur often requires adjustments to all parts of the system. This leads to an inevitable trade-off in the design of operating systems -- the overhead of persisting the achieved computation progress over power failures is detrimental to the possible amount of progress with the available energy budgets. It is, therefore, crucial to minimize the overhead of ensuring persistence. This paper presents the case that persistence should be provided as an operating-system service to achieve everlasting operating capabilities. Triggered by power-failure interrupts, an implicit persistence service for the processor status of a process preserves progress on the CPU-instruction level. This interrupt only triggers if necessary so that no power-state polling is needed. We outline architectures for everlasting systems and discuss their benefits and drawbacks compared to existing approaches. Thereby, the operating system provides persistence as a service at run-time to the application, with minimal overhead. Our approach enables the separation of the application from energy-supply state estimation, as well as state-preserving logic for software and hardware components

Worst-Case Energy Consumption Analysis for Energy-Constrained Embedded Systems

Abstract—The fact that energy is a scarce resource in many embedded real-time systems creates the need for energy-aware task schedulers, which not only guarantee timing constraints but also consider energy consumption. Unfortunately, existing approaches to analyze the worst-case execution time (WCET) of a task usually cannot be directly applied to determine its worst-case energy consumption (WCEC) due to execution time and energy consumption not being closely correlated on many state-of-the-art processors. Instead, a WCEC analyzer must take into account the particular energy characteristics of a target platform. In this paper, we present 0g, a comprehensive approach to WCEC analysis that combines different techniques to speed up the analysis and to improve results. If detailed knowledge about the energy costs of instructions on the target platform is available, our tool is able to compute upper bounds for the WCEC by statically analyzing the program code. Otherwise, a novel ap-proach allows 0g to determine the WCEC by measurement after having identified a set of suitable program inputs based on an auxiliary energy model, which specifies the energy consumption of instructions in relation to each other. Our experiments for three target platforms show that 0g provides precise WCEC estimates. I

A Resource-Aware Nearest-Neighbor Search Algorithm for K-Dimensional Trees

Abstract-Kd-tree search is widely used today in computer vision -for example in object recognition to process a large set of features and identify the objects in a scene. However, the search times vary widely based on the size of the data set to be processed, the number of objects present in the frame, the size and shape of the kd-tree, etc. Constraining the search interval is extremely critical for real-time applications in order to avoid frame drops and to achieve a good response time. The inherent parallelism in the algorithm can be exploited by using massively parallel architectures like many-core processors. However, the variation in execution time is more pronounced on such hardware (HW) due to the presence of shared resources and dynamically varying load situations created by applications running concurrently. In this work, we propose a new resource-aware nearest-neighbor search algorithm for kd-trees on many-core processors. The novel algorithm can adapt itself to the dynamically varying load on a many-core processor and can achieve a good response time and avoid frame drops. The results show significant improvements in performance and detection rate compared to the conventional approach while the simplicity of the conventional algorithm is retained in the new model

Globaliseerumise seosed sissetulekute ebavõrdsusega arenguriikide ning üleminekujärgus majandusega riikide näitel

Üha süvenev sissetulekute ebavõrdsus on maailmas aktuaalne probleem, mille üle peavad järjepidevat diskussiooni nii poliitikakujundajad kui ka akadeemikud. Nii ei ole inimeste sissetulekute ebavõrdsuse kasvu probleemid mööda läinud isegi arenenud majandusega riikidest, kuid arengu- ning siirderiikides on probleem veelgi laiaulatuslikum ning tõsisem. Probleemide hulk, mida toob kaasa järjest süvenev sissetulekute ebavõrdsus arengu- ning siirderiikides on laiahaardeline ning mitmekesine, mistõttu arvatakse, et sissetulekute ebavõrdsus võib suure tõenäosusega põhjustada lähema kümne aasta jooksul maailmas olulist kahju. Nii teaduskirjanduses kui ka poliitilisel maastikul valitseb diskussioon selle üle, kas sissetulekute ebavõrdsuse allikaks on pigem riigisisene poliitika või tegu on siiski globaliseerumise näol maailmas aset leidnud loomulike arengutega. Siit tulenevalt oli bakalaureusetöö eesmärk uurida globaliseerumise majandusliku dimensiooni ning sissetulekute ebavõrdsuse vahelisi seoseid arengu- ning üleminekujärgus majandusega riikides. Töös püstitati hüpotees: mida globaliseerunum on majandus, seda väiksem on sissetulekute ebavõrdsus arengu- ning siirderiikides tulenevalt olemasolevatest teoreetilistest käsitlustest ning varasemate empiiriliste uuringute tulemustest. Püstitatud hüpoteesi kontrollimiseks viis autor läbi korrelatsioonanalüüsi kui ka mitmese regressioonanalüüsi abil modelleerimise. Valimisse kuulus kokku 53 arengu- ning siirderiiki 12 erinevast regioonist. Tulemused näitasid, et majanduslikku globaliseerumisprotsessi iseloomustavad avatud kaubavahetus ning välismaised otseinvesteeringud ei ole arengu- ning siirderiikides sissetulekute ebavõrdsust tekitavateks teguriteks ning viimaseid saab hoopis pidada sissetulekute ebavõrdsust vähendavateks mõjuriteks. Saadud uurimistulemused on kasulikud mõistmaks paremini kompleksse sissetulekute ebavõrdsuse probleemi olemust arengu- ning siirderiikides. Samuti võiksid saadud tulemused aidata kaasa arengu- ning siirderiikides tõhusa poliitika loomisele, eesmärgiga toetada sissetulekute ebavõrdsuse probleemiga edukamat toimetulekut.http://www.ester.ee/record=b5144161*es