Investigating an API for resilient exascale computing.

Increased HPC capability comes with increased complexity, part counts, and fault occurrences. In- creasing the resilience of systems and applications to faults is a critical requirement facing the viability of exascale systems, as the overhead of traditional checkpoint/restart is projected to outweigh its bene ts due to fault rates outpacing I/O bandwidths. As faults occur and propagate throughout hardware and software layers, pervasive noti cation and handling mechanisms are necessary. This report describes an initial investigation of fault types and programming interfaces to mitigate them. Proof-of-concept APIs are presented for the frequent and important cases of memory errors and node failures, and a strategy proposed for lesystem failures. These involve changes to the operating system, runtime, I/O library, and application layers. While a single API for fault handling among hardware and OS and application system-wide remains elusive, the e ort increased our understanding of both the mountainous challenges and the promising trailheads.

Energy efficiency in HPC with and without knowledge of applications and services

International audienceThe constant demand of raw performance in high performance computing often leads to high performance systems' over-provisioning which in turn can result in a colossal energy waste due to workload/application variation over time. Proposing energy efficient solutions in the context of large scale HPC is a real unavoidable challenge. This paper explores two alternative approaches (with or without knowledge of applications and services) dealing with the same goal: reducing the energy usage of large scale infrastructures which support HPC applications. This article describes the first approach "with knowledge of applications and services'' which enables users to choose the less consuming implementation of services. Based on the energy consumption estimation of the different implementations (protocols) for each service, this approach is validated on the case of fault tolerance service in HPC. The approach "without knowledge'' allows some intelligent framework to observe the life of HPC systems and proposes some energy reduction schemes. This framework automatically estimates the energy consumption of the HPC system in order to apply power saving schemes. Both approaches are experimentally evaluated and analyzed in terms of energy efficiency

Lazy Fault Recovery for Redundant Mpi

Distributed Systems (DS) where multiple computers share a workload across a network, are used everywhere, from data intensive computations to storage and machine learning. DS provide a relatively cheap and efficient solution that allows stability with improved performance for computational intensive applications. In a DS faults and failures are the norm not the exception. At any moment data corruption can occur especially since a DS usually consists of hundred to thousands of units of commodity hardware. The large number and quality of components guarantees, by probability, that at any given time some of the components will not be working and some of them will not recover from failure. DS can experience problems caused by application bugs, operating systems bugs, failures with disks, memory, connectors, networking, power supply, and other components; therefore, constant monitoring and failure detection are fundamental. Automatic recovery must be integral to the system. One of the most commonly used programming languages for DS is Message Passing Interface (MPI). Unfortunately MPI does not support fault detection or recovery. In this thesis, we build a recovery mechanism based on replicas that works on top of the asynchronous fault detection implemented in previous work. Results shows that our recovery implementation is successful and the overhead in execution time is minimal

Energy-efficient checkpointing in high-throughput cycle-stealing distributed systems

Checkpointing is a fault-tolerance mechanism commonly used in High Throughput Computing (HTC) environments to allow the execution of long-running computational tasks on compute resources subject to hardware or software failures as well as interruptions from resource owners and more important tasks. Until recently many researchers have focused on the performance gains achieved through checkpointing, but now with growing scrutiny of the energy consumption of IT infrastructures it is increasingly important to understand the energy impact of checkpointing within an HTC environment. In this paper we demonstrate through trace-driven simulation of real-world datasets that existing checkpointing strategies are inadequate at maintaining an acceptable level of energy consumption whilst maintaing the performance gains expected with checkpointing. Furthermore, we identify factors important in deciding whether to exploit checkpointing within an HTC environment, and propose novel strategies to curtail the energy consumption of checkpointing approaches whist maintaining the performance benefits

Simple Energy Aware Scheduler: An Empirical Evaluation

Mobile devices have evolved from single purpose devices, such as mobile phone, into general purpose multi-core computers with considerable unused capabilities. Therefore, several researchers have considered harnessing the power of these battery-powered devices for distributed computing. Despite their ever-growing capabilities, using battery as power source for mobile devices represents a major challenge for applying traditional distributed computing techniques. Particularly, researchers aimed at using mobile devices as resources for executing computationally intensive task. Different job scheduling algorithms were proposed with this aim, but many of them require information that is unavailable or difficult to obtain in real-life environments, such as how much energy would require a job to be finished. In this context, Simple Energy Aware Scheduler (SEAS) is a scheduling technique for computational intensive Mobile Grids that only require easily accessible information. It was proposed in 2010 and it has been the base for a range of research work. Despite being described as easily implementable in real-life scenarios, SEAS and other SEAS-improvements works have always been evaluated using simulations. In this work, we present a distributed computing platform for mobile devices that support SEAS and empirical evaluation of the SEAS scheduler. This evaluation followed the methodology of the original SEAS evaluation, in which Random and Round Robin schedulers were used as baselines. Although the original evaluation was performed by simulation using notebooks profile instead of smartphones and tablets, results confirms that SEAS outperforms the baseline schedulers.Fil: Pérez Campos, Ana Bella. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas; ArgentinaFil: Rodriguez, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Instituto Superior de Ingeniería del Software. Universidad Nacional del Centro de la Provincia de Buenos Aires. Instituto Superior de Ingeniería del Software; ArgentinaFil: Zunino Suarez, Alejandro Octavio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Instituto Superior de Ingeniería del Software. Universidad Nacional del Centro de la Provincia de Buenos Aires. Instituto Superior de Ingeniería del Software; Argentin

Cooperative checkpointing for supercomputing systems

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 91-94).A system-level checkpointing mechanism, with global knowledge of the state and health of the machine, can improve performance and reliability by dynamically deciding when to skip checkpoint requests made by applications. This thesis presents such a technique, called cooperative checkpointing, and models its behavior as an online algorithm. Where C is the checkpoint overhead and I is the request interval, a worst-case analysis proves a lower bound of (2 + [C/I])-competitiveness for deterministic cooperative checkpointing algorithms, and proves that a number of simple algorithms meet this bound. Using an expected-case analysis, this thesis proves that an optimal periodic checkpointing algorithm that assumes an exponential failure distribution may be arbitrarily bad relative to an optimal cooperative checkpointing algorithm that permits a general failure distribution. Calculations suggest that, under realistic conditions, an application using cooperative checkpointing may make progress 4 times faster than one using periodic checkpointing. Finally, the thesis suggests an embodiment of cooperative checkpointing for a large-scale high performance computer system and presents the results of some preliminary simulations. These results show that, in extreme cases, cooperative checkpointing improved system utilization by more than 25%, reduced bounded slowdown by a factor of 9, while simultaneously reducing the amount of work lost due to failures by 30%. This thesis contributes a unique approach to providing large-scale system reliability through cooperative checkpointing, techniques for analyzing the approach, and blueprints for implementing it in practice.by Adam Jamison Oliner.M.Eng