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COMPUTER 1999年第6期32卷 72-+页

作者： Dahlgren, F Torrellas, J Ericsson Mobile Commun Lund Sweden Univ Illinois Dept Comp Sci Urbana IL 61801 USA

The shared-memory concept makes it easier to write parallel programs, but tuning the application to reduce the impact of frequent long-latency memory accesses still requires substantial programmer effort. Researchers have proposed using compilers, operating systems, or architectures to improve performance by allocating data close to the processors that use it, The Cache-Only Memory Architecture (CO,MA) increases the chances of data being available locally because the hardware transparently replicates the data and migrates it to the memory module of the node that is currently accessing it. Each memory module acts as a huge cache memory in which each block has a tag with the address and the state. The authors explain the functionality, architecture, performance, and complexity of COMA systems. They also outline different COMA designs, compare COMA to traditional nonuniform memory access (NUMA) systems, and describe proposed improvements in NUMA systems that target the same performance obstacles as COMA.

关键词： COMA Cache-Only Memory Architecture NUMA systems cache storage compilers data allocation data replication frequent long latency memory accesses huge cache memory memory architecture memory module nonuniform memory access operating systems parallel programming parallel programs performance obstacles programmer effort shared memory concept shared memory systems storage management

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parallel EFFICIENCY CAN BE GREATER THAN UNITY

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parallel COMPUTING 1986年第3期3卷 261-262页

作者： PARKINSON, D DAP Support Unit Queen Mary College London E1 4NS United Kingdom

It is shown that in some case parallel architectures with p processors can show speed-ups greater than p and efficiences greater than unity.

关键词： efficiency parallel computers parallel programs performance analysis

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Pipelines and Beyond: Graph Types for ADTs with Futures

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PROCEEDINGS OF THE ACM ON PROGRAMMING LANGUAGES-PACMPL 2024年第POPL期8卷 482-511页

作者： Rinaldi, Francis Wunder, June de Amorim, Arthur Azevedo Muller, Stefan K. IIT Chicago IL 60616 USA Boston Univ Boston MA USA

parallel programs are frequently modeled as dependency or cost graphs, which can be used to detect various bugs, or simply to visualize the parallel structure of the code. However, such graphs reflect just one particular execution and are typically constructed in a post-hoc manner. Graph types, which were introduced recently to mitigate this problem, can be assigned statically to a program by a type system and compactly represent the family of all graphs that could result from the program. Unfortunately, prior work is restricted in its treatment of futures, an increasingly common and especially dynamic form of parallelism. In short, each instance of a future must be statically paired with a vertex name. Previously, this led to the restriction that futures could not be placed in collections or be used to construct data structures. Doing so is not a niche exercise: such structures form the basis of numerous algorithms that use forms of pipelining to achieve performance not attainable without futures. All but the most limited of these examples are out of reach of prior graph type systems. In this paper, we propose a graph type system that allows for almost arbitrary combinations of futures and recursive data types. We do so by indexing datatypes with a type-level vertex structure, a codata structure that supplies unique vertex names to the futures in a data structure. We prove the soundness of the system in a parallel core calculus annotated with vertex structures and associated operations. Although the calculus is annotated, this is merely for convenience in defining the type system. We prove that it is possible to annotate arbitrary recursive types with vertex structures, and show using a prototype inference engine that these annotations can be inferred from OCaml-like source code for several complex parallel algorithms.

关键词： parallel programs graph types cost graphs computation graphs futures pipelining affine type system

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Fault Detection in Multi-Threaded C++ Server Applications

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ELECTRONIC NOTES IN THEORETICAL COMPUTER SCIENCE 2007年第9期174卷 5-22页

作者： Muehlenfeld, Arndt Wotawa, Franz Graz Univ Technol Inst Software Technol Graz Austria

Due to increasing demands in processing power on the one hand, but the physical limit on CPU clock speed on the other hand, multi-threaded programming is becoming more important in current applications. Unfortunately, multi-threaded programs are prone to programming mistakes that result in hard to find defects, mainly race-conditions and deadlocks. The need for tools that help finding these faults is immanent, but currently available tools are either difficult to use because of the need for annotations, unable to cope with more than a few 10 kLOC, or issue too many false warnings. This paper describes experiments with the freely available tool Helgrind and results obtained by using it for debugging a server application comprising 500 kLOC. We present improvements to the runtime analysis of C++ programs that result in a dramatic reduction of false warnings.

关键词： data races race conditions debugging parallel programs synchronization multi-threaded programming object-oriented programming static-dynamic co-analysis

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Efficient and precise datarace detection for multithreaded object-oriented programs

Efficient and precise datarace detection for multithreaded o...

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Conference on Programming Language Design and Implementation (PLDI 02)

作者： Choi, JD Lee, KW Loginov, A O'Callahan, R Sarkar, V Sridharan, M IBM Corp Thomas J Watson Res Ctr Yorktown Hts NY 10598 USA Univ Washington Seattle WA 98195 USA Univ Wisconsin Madison WI 53706 USA MIT Cambridge MA 02139 USA

We present a novel approach to dynamic datarace detection for multithreaded object-oriented programs. Past techniques for on-the-fly datarace detection either sacrificed precision for performance, leading to many false positive datarace reports, or maintained precision but incurred significant overheads in the range of 3x to 30x. In contrast, our approach results in very few false positives and runtime overhead in the 13% to 42% range, making it both efficient and precise. This performance improvement is the result of a unique combination of complementary static and dynamic optimization techniques.

关键词： experimentation languages measurement performance dataraces race conditions debugging parallel programs synchronization multithreaded programming object-oriented programming static-dynamic co-analysis

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Optimization of 3D Fusion Devices 16

Optimization of 3D Fusion Devices

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Conference on Diversity, Big Data, and Science at Scale (XSEDE)

作者： Castejon, Francisco Gomez-Iglesias, Antonio Lopez-Fraguas, Antonio CIEMAT Natl Fus Lab Madrid Spain Univ Texas Austin Texas Adv Comp Ctr Austin TX 78712 USA

ISBN: (纸本)9781450347556

Optimization and design of nuclear fusion devices is a complex task with large computational requirements. The complexity is defined by the number of parameters involved in every single possible optimization function that focuses on the different aspects of plasma confinement. This paper presents a possible optimization of an existing nuclear fusion device. The optimization process is carried out by a parallel algorithm specifically designed to work with large scale problems. While the focus of the paper is fusion, the approach used can be applied to any other large scale problem. We have run our experiments on an HPC cluster. The results show the validity of our approach and how complex scientific problems can benefit from the outcomes of this work.

关键词： distributed optimization nuclear fusion parallel programs

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Uniform Substitution for Dynamic Logic with Communicating Hybrid programs 1

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29th International Conference on Automated Deduction (CADE)

作者： Brieger, Marvin Mitsch, Stefan Platzer, Andre Ludwig Maximilians Univ Munchen Munich Germany Carnegie Mellon Univ Pittsburgh PA USA Karlsruhe Inst Technol Karlsruhe Germany

ISBN: (数字)9783031384998

ISBN: (纸本)9783031384998;9783031384981

This paper introduces a uniform substitution calculus for dL(CHP), the dynamic logic of communicating hybrid programs. Uniform substitution enables parsimonious prover kernels by using axioms instead of axiom schemata. Instantiations can be recovered from a single proof rule responsible for soundness-critical instantiation checks rather than being spread across axiom schemata in side conditions. Even though communication and parallelism reasoning are notorious for necessitating subtle soundness-critical side conditions, uniform substitution when generalized to dL(CHP) manages to limit and isolate their conceptual overhead. Since uniform substitution has proven to simplify the implementation of hybrid systems provers substantially, uniform substitution for dL(CHP) paves the way for a parsimonious implementation of theorem provers for hybrid systems with communication and parallelism.

关键词： Uniform substitution parallel programs Differential dynamic logic Assumption-commitment reasoning CSP

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Novel Designs for Memory Checkers Using Semantics and Digital Sequential Circuits 15th

Novel Designs for Memory Checkers Using Semantics and Digita...

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15th International Conference on Computational Science and Its Applications (ICCSA)

作者： El-Zawawy, Mohamed A. Al Imam Mohammad Ibn Saud Islamic Univ IMSIU Coll Comp & Informat Sci Riyadh Saudi Arabia Cairo Univ Dept Math Fac Sci Giza 12613 Egypt

ISBN: (纸本)9783319214108;9783319214092

Memory safety breaches have been main tools in many of the latest security vulnerabilities. Therefore memory safety is critical and attractive property for any piece of code. Separation logic can be realized as a mathematical tool to reason about memory safety of programs. An important technique for modern parallel programming is multithreading. For a multi-threaded model of programming (Core-Par-C), this paper introduces an accurate semantics which is employed to mathematically prove the undecidability of memory-safety of Core-Par-C programs. The paper also proposes a design for a hardware to act as an efficient memory checker against memory errors.

关键词： Operational semantics Separation logic Memory-safety parallel programs Digital sequential circuits

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Using parallel Distributed Reasoning for Monitoring Computing Networks

Using Parallel Distributed Reasoning for Monitoring Computin...

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MILCOM Military Communications Conference

作者： Musman, S. Mitre Corp Mclean VA 22215 USA

ISBN: (纸本)9781424481804

We describe a distributed reasoning system called Otto-Mate that is used to detect, reason about, and respond to incidents on a computing network. Events for monitoring computing networks occur at different system levels. Some information might relate to data, some might be operating system specific, some application or service related, some could be network related, and from each there will be compound events that describe incident effects and information about the situation context. All together there can be thousands of events per second. Today's approaches to monitoring networks are typically centralized, sending events over the network to a single engine for analysis. Centralized monitoring ultimately cannot scale to address the volume of events that one would ideally like to be able to monitor, so techniques of today often make severe compromises relating to the events that they ingest. Centralized monitoring creates a single point of failure and also generates significant network load. To overcome these deficiencies we have developed a more distributed, approach: our reasoner agents can (in theory) be installed on every monitored resources and the reasoner language (used for programming the reasoners) enables knowledge in a reasoner's working memory to be synchronized over multiple reasoners enabling them to implement parallel distributed reasoning algorithms that are able detect event patterns irrespective of whether the events are local or remote. Distributing the reasoning makes the system extremely resilient. Additionally, since the knowledge shared between the reasoning agents represents summary information, and because many on-line event correlation algorithms often suppress reporting once an incident has been reported, the amount of network load needed to support the distributed monitoring can actually be reduced. To demonstrate our approach we describe its application to the monitoring of a computing network that has been instrumented to protect it ag

关键词： network and security monitoring event correlation distributed reasoning parallel programs autonomic response intelligent agents

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Efficient Thread Labeling for Monitoring programs with Nested parallelism

Efficient Thread Labeling for Monitoring Programs with Neste...

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International Conference on Future Generation Communication and Networking

作者： Ha, Ok-Kyoon Kim, Sun-Sook Jun, Yong-Kee Gyeongsang Natl Univ RICIC Dept Informat Jinju 660701 South Korea Gyeongsang Natl Univ Dept Informat Jinju South Korea Gyeongsang Natl Univ Specialized Grad Sch Aerosp Engn Jinju South Korea

ISBN: (纸本)9783642176036

It is difficult and cumbersome to detect data races occurred in an execution of parallel programs. Any on-the-fly race detection techniques using Lamport's happened-before relation needs a thread labeling scheme for generating unique identifiers which maintain logical concurrency information for the parallel threads. NR labeling is an efficient thread labeling scheme for the fork-join program model with nested parallelism, because its efficiency depends only on the nesting depth for every fork and join operation. This paper presents an Unproved NR, labeling, called e-NR labeling, in which every thread generates its label by inheriting the pointer to its ancestor list from the parent threads or by updating the pointer in a constant amount of time and space. This labeling is more efficient than the NR labeling, because its efficiency does not depend on the nesting depth for every fork and join operation. Some experiments were performed with OpenMP programs having nesting depths of three or four and maximum parallelisms varying from 10,000 to 1,000,000. The results show that e-NR is 5 times faster than NR labeling and 4.3 times faster than OS labeling in the average time for creating and maintaining the thread labels. In average space required for labeling, it is 3.5 times smaller than NR labeling and 3 times smaller than OS labeling.

关键词： thread labeling happened-before relation logical concurrency data races parallel programs nested parallelism NR labeling

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