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CAS-DSM: A compiler assisted software distributed shared memory

INTERNATIONAL JOURNAL OF PARALLEL PROGRAMMING 2004年第2期32卷 77-122页

作者： Manoj, NP Manjunath, KV Govindarajan, R Hewlett Packard India Software Operat Bangalore 560052 Karnataka India Univ Michigan Ann Arbor MI 48109 USA Indian Inst Sci Supercomp Educ & Res Ctr Dept Comp Sci & Automat Bangalore 560012 Karnataka India

Traditional software distributed shared memory (DSM) systems rely on the virtual memory management mechanisms to detect accesses to shared memory locations and maintain their consistency. The resulting involvement of the OS (kernel) and the associated overhead which is significant, can be avoided by careful compile time analysis and code instrumentation. In this paper, we propose such a Compiler Assisted software support approach (CAS-DSM). In the CAS-DSM implementation, the involvement of the OS kernel is avoided by instrumenting the application code at the source level. The overhead caused by the execution of the instrumented code is reduced through several aggressive compile time optimizations. Finally, we also address the issue of reducing certain overheads in polling-based implementation of receiving asynchronous messages. We used SUIF, a public domain compiler tool, to implement compile time analysis, instrumentation and optimizations. We modified CVM, a publicly available software DSM to support the instrumentation inserted by the compiler. Detailed performance evaluation of CAS-DSM is reported using a set of Splash/Splash2 parallel application benchmarks on a distributed memory IBM SP-2 machine. CAS-DSM achieved moderate to good performance improvements for most of the applications compared to the original CVM implementation. Reducing the overheads in polling-based implementation improves the performance of CAS-DSM significantly resulting in an overall improvement of 12-52% over the original CVM implementation.

关键词： Coherent Virtual Machine (CVM) software distributed shared memory Stanford University Intermediate Form (SUIF) performance evaluation

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Optimizing OpenMP programs on software distributed shared memory systems

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INTERNATIONAL JOURNAL OF PARALLEL PROGRAMMING 2003年第3期31卷 225-249页

作者： Min, SJ Basumallik, A Eigenmann, R Purdue Univ Sch Elect & Comp Engn W Lafayette IN 47907 USA

This paper describes compiler techniques that can translate standard OpenMP applications into code for distributed computer systems. OpenMP has emerged as an important model and language extension for shared-memory parallel programming. However, despite OpenMP's success on these platforms, it is not currently being used on distributed system. The long-term goal of our project is to quantify the degree to which such a use is possible and develop supporting compiler techniques. Our present compiler techniques translate OpenMP programs into a form suitable for execution on a software DSM system. We have implemented a compiler that performs this basic translation, and we have studied a number of hand optimizations that improve the baseline performance. Our approach complements related efforts that have proposed language extensions for efficient execution of OpenMP programs on distributed systems. Our results show that, while kernel benchmarks can show high efficiency of OpenMP programs on distributed systems, full applications need careful consideration of shared data access patterns. A naive translation ( similar to OpenMP compilers for SMPs) leads to acceptable performance in very few applications only. However, additional optimizations, including access privatization, selective touch, and dynamic scheduling, resulting in 31% average improvement on our benchmarks.

关键词： OpenMP applications software distributed shared memory benchmarks performance characteristics optimizations

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Naplus: a software distributed shared memory for virtual clusters in the cloud

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software-PRACTICE & EXPERIENCE 2017年第9期47卷 1201-1220页

作者： Zeng, Lingfang Wang, Yang Kent, Kenneth B. Xiao, Ziliang Huazhong Univ Sci & Technol Wuhan Natl Lab Optoelect Sch Comp Wuhan Hubei Peoples R China Chinese Acad Sci Shenzhen Inst Adv Technol Shenzhen Peoples R China Univ New Brunswick IBM Ctr Adv Studies Atlantic Fredericton NB Canada

Virtual clusters (VCs) have exhibited various advantages over traditional cluster computing platforms by virtue of their extensibility, reconfigurability, and maintainability. As such, they have become a major execution environment for cloud-based cluster applications. However, compared with traditional clusters, their distributed-memory programming paradigm still remains largely unchanged, which implies that cluster applications cannot be efficiently deployed in VCs, especially when virtual machines (VMs) are running in different physical hosts. Recently, some efforts have been made to improve inter-VM communication, resulting in many studies on how cluster applications could take advantages of VCs. However, most of them mainly focus on the situation that the VMs are all coresident on the same physical machine where the message passing mechanism is usually optimized away by exploiting the host's shared memory. In this paper, we present a design and implementation of Naplus, a kernel-based virtual machine approach to the inter-VM communications that are across different physical hosts. Naplus is based on Nahanni, a mechanism for shared-memory communication in virtual environments. As such, it not only inherits the major merits of Nahanni with respect to flexible data structures and efficient synchronization but also achieves a shared-memory paradigm among VMs. With Naplus, we enable the size of shared space to be maximized as large as the sum of each machine's local memory to accommodate cluster applications with large memory footprints. We prototype Naplus in a dual-host system where an empirical study is conducted to show the effectiveness of the Naplus approach in achieving distributed shared memory for VCs in data centers. Copyright (C) 2017 John Wiley & Sons, Ltd.

关键词： virtual cluster software distributed shared memory inter-VM shared memory cloud computing cluster computing

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SilkRoad: A multithreaded runtime system with software distributed shared memory for SMP clusters

SilkRoad: A multithreaded runtime system with software distr...

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2nd Annual IEEE International Conference on Cluster Computing

作者： Peng, L Wong, WF Feng, MD Yuen, CK Natl Univ Singapore Dept Comp Sci Singapore 117543 Singapore

ISBN: (纸本)0769508960

Constructing multithreaded parallel systems with software distributed shared memory (DSM) is an attractive trend in cluster computing. distributed Cilk (Cilk 5.1) is a multithreaded runtime system for SMP clusters with support for the divide-and-conquer programming paradigm. However if lacks support for user-level shared memory. In this paper we describe SilkRoad, an extension of distributed Cilk which implements the Lazy Release Consistency (LRC) memory model. In the SilkRoad runtime system, system central information is kept consistent by means of a backing store - just as if is in the original distributed Cilk, while the user's cluster wide shared data is kept consistent by LRC. LRC enables SilkRoad programmers to define and use shared variables between the threads running on different nodes in a cluster This greatly enlarges the scope of supported programming paradigms in Cilk. Besides testing its performance, we also compared SilkRoad with TreadMarks, an LRC software DSM system for clusters with no support of multithreading. The results show that with the hybrid memory model of dag-consistency and LRC, multithreaded SilkRoad programs written in a divide-and-conquer fashion with good data locality can achieve comparable performance with the corresponding multiple-process TreadMarks programs.

关键词： cluster computing multithreading software distributed shared memory

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Optimizing OpenMP programs on software distributed shared memory systems

Optimizing OpenMP programs on software distributed shared me...

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International Symposium on High Performance Computing

作者： Min, SJ Basumallik, A Eigenmann, R Purdue Univ Sch Elect & Comp Engn W Lafayette IN 47907 USA

关键词： OpenMP applications software distributed shared memory benchmarks performance characteristics optimizations

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Achieving performance under OpenMP on ccNUMA and software distributed shared memory systems

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CONCURRENCY AND COMPUTATION-PRACTICE & EXPERIENCE 2002年第8-9期14卷 713-739页

作者： Chapman, B Bregier, F Patil, A Prabhakar, A Univ Houston Dept Comp Sci Houston TX 77204 USA

OpenMP is emerging as a viable high-level programming model for shared memory parallel systems. It was conceived to enable easy, portable application development on this range of systems, and it has also been implemented on cache-coherent Non-Uniform memory Access (ccNUMA) architectures. Unfortunately, it is hard to obtain high performance on the latter architecture, particularly when large numbers of threads are involved. In this paper, we discuss the difficulties faced when writing OpenMP programs for ccNUMA systems, and explain how the vendors have attempted to overcome them. We focus on one such system, the SGI Origin 2000, and perform a variety of experiments designed to illustrate the impact of the vendor's efforts. We compare codes written in a standard, loop-level parallel style under OpenMP with alternative versions written in a Single Program Multiple Data (SPMD) fashion, also realized via OpenMP, and show that the latter consistently provides superior performance. A carefully chosen set of language extensions can help us translate programs from the former style to the latter (or to compile directly, but in a similar manner). Syntax for these extensions can be borrowed from HPF, and some aspects of HPF compiler technology can help the translation process. It is our expectation that an extended language, if well compiled, would improve the attractiveness of OpenMP as a language for high-performance computation on an important class of modern architectures. Copyright (C) 2002 John Wiley Sons, Ltd.

关键词： shared memory parallel programming OpenMP ccNUMA architectures restructuring data locality data distributions software distributed shared memory

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Scheduling loop applications in software distributed shared memory systems

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IEICE TRANSACTIONS ON INFORMATION AND SYSTEMS 2000年第9期E83D卷 1721-1730页

作者： Liang, TY Shieh, CK Liu, DC Natl Cheng Kung Univ Dept Elect Engn Tainan 70101 Taiwan

This paper first examines the issues related to scheduling loop applications on a software distributed shared memory (DSM) system. Then, a dynamic scheduling scheme is developed based on the examined issues to enhance the performance of loop applications on DSM. Compared with previous works, the proposed scheme has several specialties. The first is that the workload of processors can be effectively balanced even when the computational capabilities of processors and the computational needs of threads are not identical. The second is it divides thread mapping into two phases, each with one consideration, i.e,, load balance or communication cost, and adopts thread migration and exchange in the two phases, respectively. The third is the exploitation of data sharing among threads to reduce data-consistency communication, and the last is to attack the negative effect of the unnecessary inter-node sharing caused by thread re-mapping. The proposed scheme has been implemented on a page-based DSM system called Cohesion. Our experiments show that the proposed scheme is more effective to improve the performance of the test programs than related schemes.

关键词： software distributed shared memory loop application load balance communication cost unnecessary inter-node sharing

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Running OpenMP applications efficiently on an everything-shared SDSM

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JOURNAL OF PARALLEL AND distributed COMPUTING 2006年第5期66卷 647-658页

作者： Costa, JJ Cortes, T Martorell, X Ayguade, E Labarta, J Univ Politecn Catalunya Dept Arquitectura Computadors Barcelona Spain

Traditional software distributed shared memory (SDSM) systems modify the semantics of a real hardware shared memory system by relaxing the coherence semantic and by limiting the memory regions that are actually shared. These semantic modifications are done to improve performance of the applications using it. In this paper. we will show that a SDSM system that behaves like a real shared memory system (without the afore-mentioned relaxations) can also be used to execute OpenMP applications and achieve similar speedups as the ones obtained by traditional SDSM systems. This performance can be achieved by encouraging the cooperation between the SDSM and the OpenMP runtime instead of relaxing the semantics of the shared memory. In addition, techniques like boundaries alignment and page presend are demonstrated as very useful to overcome the limitations of the current SDSM systems. (c) 2005 Elsevier Inc. All rights reserved.

关键词： OpenMP software distributed shared memory scalability adaptability cooperation

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Log-based rollback recovery without checkpoints of shared memory in software DSM

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JOURNAL OF SUPERCOMPUTING 2006年第2期35卷 141-154页

作者： Park, S Maeng, SR Korea Adv Inst Sci & Technol Dept Elect Engn & Comp Sci Taejon 305701 South Korea

A common approach to fault-tolerant software DSM is to take checkpoints with message logging. Our remote logging has low overhead because each node saves the coherence-related data into the memory of a remote node through a high-speed system area network. For more lightweight fault-tolerant DSM, in this paper, we mainly focused on eliminating shared memory checkpointing during failure-free execution. Each node independently takes the checkpoints of execution states and non-shared data only. When a node fails, it regenerates its pages from the remote copies in live nodes. In order to efficiently reconstruct pages, we also introduced a XOR-diffing technique. The diff logs, which have been created by XOR operations during failure-free execution, can be applicable to any version of remote copies either backward or forward for recovery. Our scheme reduces the checkpointing overhead and also alleviates the imbalance in execution times among nodes due to independent checkpointing.

关键词： checkpointing fault tolerance rollback recovery logging software distributed shared memory cluster computing

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Improving the execution efficiency of barrier synchronization in software DSM through static analysis

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INTERNATIONAL JOURNAL OF HIGH SPEED COMPUTING 2000年第3期11卷 167-188页

作者： Lee, JB Jhon, CS Pusan Natl Univ Res Inst Comp Informat & Commun Pusan 609735 South Korea Seoul Natl Univ Sch Comp Sci & Engn Seoul 151742 South Korea

In software distributed shared memory (SDSM) systems, the large coherence granularity imposed by virtual memory page size tends to induce false sharing, which may lead to heavy network traffic or useless page misses on barrier operations. In this paper, we propose a method to alleviate the coherence overhead of barrier synchronization in the SDSM systems. It performs static analysis on a shared-memory program to examine data dependency between processors across global barriers, and then special primitives are inserted into the program in order to exploit the dependency information at run time. If the data modified before a barrier will be accessed by some of the other processors after the barrier, coherence messages are transferred only to the processors through the inserted primitives. Furthermore, if the modified data will not be used by any other processors, the primitives enforce the coherence messages to be delivered only to master process after the parallel execution of the program completes. We implemented the static analysis with SUIF parallelizing compiler and then evaluated the execution performance of modified programs in a 16-node SDSM system supporting AURC protocol. The experimental results show that our method is very effective at reducing the useless coherence messages, and also can improve the execution time substantially by reducing false sharing misses.

关键词： software distributed shared memory data coherence relaxed memory models Automatic Update Release Consistency data dependency analysis run-time support

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