Disengaged Scheduling for Fair, Protected Access to Fast Computational Accelerators

Today’s operating systems treat GPUs and other computational accelerators as if they were simple devices, with bounded and predictable response times. With accelerators assuming an increasing share of the workload on modern machines, this strategy is already problematic, and likely to become untenable soon. If the operating system is to enforce fair sharing of the machine, it must assume responsibility for accelerator scheduling and resource management. Fair, safe scheduling is a particular challenge on fast accelerators, which allow applications to avoid kernel-crossing overhead by interacting directly with the device. We propose a disengaged scheduling strategy in which the kernel intercedes between applications and the accelerator on an infrequent basis, to monitor their use of accelerator cycles and to determine which applications should be granted access over the next time interval. Our strategy assumes a well defined, narrow interface exported by the accelerator. We build upon such an interface, systematically inferred for the latest Nvidia GPUs. We construct several example schedulers, including Disengaged Timeslice with overuse control that guarantees fairness and Disengaged Fair Queueing that is effective in limiting resource idleness, but probabilistic. Both schedulers ensure fair sharing of the GPU, even among uncooperative or adversarial applications; Disengaged Fair Queueing incurs a 4 % overhead on average (max 18%) compared to direct devic

Procesamiento distribuido y paralelo de bajo costo basado en cloud&movil

Actualmente el procesamiento intensivo se realiza a través de estructuras HPC híbridas (Grid, Cluster, Cloud) utilizando procesadores de arquitectura x86 y GPUs Nvidia, AMD o Intel, incurriendo en altísimos costos económicos y energéticos. Sin embargo, gracias a la evolución constante del hardware y con el advenimiento de los dispositivos móviles/microcomputadores con CPUs/GPUs ARM acompañado de la masividad de los mismos es posible pensar en una solución de bajo costo y consumo energético para solventar este tipo de problemas. Estos dispositivos incrementan su capacidad, eficiencia, estabilidad y potencia a diario, mientras ganan mercado, conservando un bajo costo, tamaño y consumo energético. A su vez, presentan lapsos de ociosidad, lo que representa una gran capacidad de recursos desaprovechados. Por tal motivo, el objetivo de este trabajo es presentar un prototipo de arquitectura distribuida dinámica, escalable y redundante geográficamente para explotar esta disponibilidad y realizar procesamiento intensivo aprovechando recursos y reduciendo costos.XVIII Workshop de Procesamiento Distribuido y Paralelo (WPDP

Energy efficient copy distributing status aware routing mechanism in opportunistic network

In opportunistic network, the relation between the node energy and message spreading degree is tradeoff. As a result, the network performance can be dramatically improved in limited resource scenarios by an effective routing me-chanism considering the node energy and copy status. Both the message spreading degree and node residual energy were taken into consideration, and then combined with the e probability predicting methods, an energy efficient copy distributing status aware routing mechanism was proposed, which could be used to choose the relay nodes reasonably. Numerical results show that the overhead can be reduced efficiently, and the message delivery ratio and latency can also be optimized