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acm sigplan NOTICES 2014年第10期49卷 213-232页

作者： Bartenstein, Thomas W. Liu, Yu David SUNY Binghamton Binghamton NY 13902 USA

We introduce RATE TYPES, a novel type system to reason about and optimize data-intensive programs. Built around stream languages, RATE TYPES performs static quantitative reasoning about stream rates - the frequency of data items in a stream being consumed, processed, and produced. Despite the fact that streams are fundamentally dynamic, we find two essential concepts of stream rate control throughput ratio and natural rate - are intimately related to the program structure itself and can be effectively reasoned about by a type system. RATE TYPES is proven to correspond with a time-aware and parallelism-aware operational semantics. The strong correspondence result tolerates arbitrary schedules, and does not require any synchronization between stream filters. We further implement RATE TYPES, demonstrating its effectiveness in predicting stream data rates in real-world stream programs.

关键词： Stream programming data processing rates data throughput performance reasoning type systems

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StreamJIT: A Commensal Compiler for High-Performance Stream programming

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acm sigplan NOTICES 2014年第10期49卷 177-195页

作者： Bosboom, Jeffrey Rajadurai, Sumanaruban Wong, Weng-Fai Amarasinghe, Saman MIT CSAIL Cambridge MA 02139 USA Natl Univ Singapore Singapore 117548 Singapore

There are many domain libraries, but despite the performance benefits of compilation, domain-specific languages are comparatively rare due to the high cost of implementing an optimizing compiler. We propose commensal compilation, a new strategy for compiling embedded domain-specific languages by reusing the massive investment in modern language virtual machine platforms. Commensal compilers use the host language's front-end, use host platform APIs that enable back-end optimizations by the host platform JIT, and use an autotuner for optimization selection. The cost of implementing a commensal compiler is only the cost of implementing the domain-specific optimizations. We demonstrate the concept by implementing a commensal compiler for the stream programming language StreamJIT atop the Java platform. Our compiler achieves performance 2.8 times better than the StreamIt native code (via GCC) compiler with considerably less implementation effort.

关键词： Domain-specific languages embedded domain-specific languages

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Automatic task based analysis and parallelization in the context of equation based languages 14

Automatic task based analysis and parallelization in the con...

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6th international Workshop on Equation-Based object-oriented Modeling languages and Tools, EOOLT 2014

作者： Gebremedhin, Mahder Fritzson, Peter PELAB-Programming Environments Laboratory Dept. of Computer and Information Science Linköping University LinköpingSE-581 83 Sweden

ISBN: (纸本)9781450332477

This paper presents an automatic parallelization approach for handling complex task systems with heavy dependencies, including methods of analyzing dependencies, representing them in a convenient way, and processing the resulting task graph representation. We present a library-based task system representation, clustering, profiling, and scheduling approach to simplify the otherwise tedious process of parallelizing complex task systems. We have implemented a flexible and robust task system handling library to manipulate and parallelize these complex task systems on shared memory multi-core and multi-processor systems. The implementation has been developed as part of the OpenModelica simulation environment. We demonstrate methods of extracting and utilizing parallelism in the context of mathematical modeling languages. Copyright is held by the owner/author(s).

关键词： Modeling languages

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The HipHop Virtual Machine

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acm sigplan NOTICES 2014年第10期49卷 777-790页

作者： Adams, Keith Evans, Jason Maher, Bertrand Ottoni, Guilherme Paroski, Andrew Simmers, Brett Smith, Edwin Yamauchi, Owen Facebook Cambridge MA USA

The HipHop Virtual Machine (HHVM) is a JIT compiler and runtime for PHP. While PHP values are dynamically typed, real programs often have latent types that are useful for optimization once discovered. Some types can be proven through static analysis, but limitations in the ahead-of-time approach leave some types to be discovered at run time. And even though many values have latent types, PHP programs can also contain polymorphic variables and expressions, which must be handled without catastrophic slow-down. HHVM discovers latent types by structuring its JIT around the concept of a tracelet. A tracelet is approximately a basic block specialized for a particular set of run-time types for its input values. Tracelets allow HHVM to exactly and efficiently learn the types observed by the program, while using a simple compiler. This paper shows that this approach enables HHVM to achieve high levels of performance, without sacrificing compatibility or interactivity.

关键词： Design languages Performance PHP dynamic languages JIT compiler tracelet

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Accelerating Iterators in Optimizing AST Interpreters

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acm sigplan NOTICES 2014年第10期49卷 727-743页

作者： Zhang, Wei Larsen, Per Brunthaler, Stefan Franz, Michael Univ Calif Irvine Irvine CA 92697 USA

Generators offer an elegant way to express iterators. However, performance has always been their Achilles heel and has prevented widespread adoption. We present techniques to efficiently implement and optimize generators. We have implemented our optimizations in ZipPy, a modern, light-weight AST interpreter based Python 3 implementation targeting the Java virtual machine. Our implementation builds on a framework that optimizes AST interpreters using just-in-time compilation. In such a system, it is crucial that AST optimizations do not prevent subsequent optimizations. Our system was carefully designed to avoid this problem. We report an average speedup of 3.58 x for generator-bound programs. As a result, using generators no longer has downsides and programmers are free to enjoy their upsides.

关键词： languages Performance generator iterator dynamic languages optimization Python

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Staged Parser Combinators for Efficient Data Processing

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acm sigplan NOTICES 2014年第10期49卷 637-653页

作者： Jonnalagedda, Manohar Coppey, Thierry Stucki, Sandro Rompf, Tiark Odersky, Martin EPFL LAMP Zurich Switzerland EPFL DATA Zurich Switzerland

Parsers are ubiquitous in computing, and many applications depend on their performance for decoding data efficiently. Parser combinators are an intuitive tool for writing parsers: tight integration with the host language enables grammar specifications to be interleaved with processing of parse results. Unfortunately, parser combinators are typically slow due to the high overhead of the host language abstraction mechanisms that enable composition. We present a technique for eliminating such overhead. We use staging, a form of runtime code generation, to dissociate input parsing from parser composition, and eliminate intermediate data structures and computations associated with parser composition at staging time. A key challenge is to maintain support for input dependent grammars, which have no clear stage distinction. Our approach applies to top-down recursive-descent parsers as well as bottom-up nondeterministic parsers with key applications in dynamic programming on sequences, where we auto-generate code for parallel hardware. We achieve performance comparable to specialized, hand-written parsers.

关键词： Parser combinators multi-stage programming algebraic dynamic programming

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Adaptive LL(*) Parsing: The Power of Dynamic Analysis

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acm sigplan NOTICES 2014年第10期49卷 579-598页

作者： Parr, Terence Harwell, Sam Fisher, Kathleen Univ San Francisco San Francisco CA 94117 USA Univ Texas Austin Austin TX 78712 USA Tufts Univ Medford MA USA

Despite the advances made by modern parsing strategies such as PEG, LL(*), GLR, and GLL, parsing is not a solved problem. Existing approaches suffer from a number of weaknesses, including difficulties supporting side-effecting embedded actions, slow and/or unpredictable performance, and counter-intuitive matching strategies. This paper introduces the ALL(*) parsing strategy that combines the simplicity, efficiency, and predictability of conventional top-down LL(k) parsers with the power of a GLR-like mechanism to make parsing decisions. The critical innovation is to move grammar analysis to parse-time, which lets ALL(*) handle any non-left-recursive context-free grammar. ALL(*) is O(n(4)) in theory but consistently performs linearly on grammars used in practice, outperforming general strategies such as GLL and GLR by orders of magnitude. ANTLR 4 generates ALL(*) parsers and supports direct left-recursion through grammar rewriting. Widespread ANTLR 4 use (5000 downloads/month in 2013) provides evidence that ALL(*) is effective for a wide variety of applications.

关键词： Algorithms languages Theory nondeterministic parsing DFA augmented transition networks grammar ALL(*) LL(*) GLR GLL PEG

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Alembic: Automatic Locality Extraction via Migration

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acm sigplan NOTICES 2014年第10期49卷 879-894页

作者： Holt, Brandon Briggs, Preston Ceze, Luis Oskin, Mark Univ Washington Seattle WA 98195 USA

Partitioned Global Address Space (PGAS) environments simplify writing parallel code for clusters because they make data movement implicit - dereferencing global pointers automatically moves data around. However, it does not free the programmer from needing to reason about locality - poor placement of data can lead to excessive and even unnecessary communication. For this reason, modern PGAS languages such as X10, Chapel, and UPC allow programmers to express data-layout constraints and explicitly move computation. This places an extra burden on the programmer, and is less effective for applications with limited or data-dependent locality (e.g., graph analytics). This paper proposes Alembic, a new static analysis that frees programmers from having to manually move computation to exploit locality in PGAS programs. It works by determining regions of code that access the same cluster node, then transforming the code to migrate parts of the execution to increase the proportion of accesses to local data. We implement the analysis and transformation for C++ in LLVM and show that in irregular application kernels, Alembic can achieve 82% of the performance of hand-tuned communication (for comparison, naive compiler-generated communication achieves only 13%).

关键词： Compilers Distributed systems languages PGAS LLVM Locality Thread migration Continuation-passing style

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Understanding Energy Behaviors of Thread Management Constructs

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acm sigplan NOTICES 2014年第10期49卷 345-360页

作者： Pinto, Gustavo Castor, Fernando Liu, Yu David Univ Fed Pernambuco Recife PE Brazil SUNY Binghamton Binghamton NY 13902 USA

Java programmers are faced with numerous choices in managing concurrent execution on multicore platforms. These choices often have different trade-offs (e.g., performance, scalability, and correctness guarantees). This paper analyzes an additional dimension, energy consumption. It presents an empirical study aiming to illuminate the relationship between the choices and settings of thread management constructs and energy consumption. We consider three important thread management constructs in concurrent programming: explicit thread creation, fixed-size thread pooling, and work stealing. We further shed light on the energy/performance trade-off of three "tuning knobs" of these constructs: the number of threads, the task division strategy, and the characteristics of processed data. Through an extensive experimental space exploration over real-world Java programs, we produce a list of findings about the energy behaviors of concurrent programs, which are not always obvious. The study serves as a first step toward improving energy efficiency of concurrent programs on parallel architectures.

关键词： Performance and Measurement Energy Consumption Performance Thread Management Multi-threaded programming Java

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Fast Splittable Pseudorandom Number Generators

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acm sigplan NOTICES 2014年第10期49卷 453-472页

作者： Steele, Guy L., Jr. Lea, Doug Flood, Christine H. SUNY Coll Oswego Oswego NY USA Red Hat Inc Raleigh NC USA

We describe a new algorithm SPLITMIX for an object-oriented and splittable pseudorandom number generator (PRNG) that is quite fast: 9 64-bit arithmetic/logical operations per 64 bits generated. A conventional linear PRNG object provides a generate method that returns one pseudorandom value and updates the state of the PRNG, but a splittable PRNG object also has a second operation, split, that replaces the original PRNG object with two (seemingly) independent PRNG objects, by creating and returning a new such object and updating the state of the original object. Splittable PRNG objects make it easy to organize the use of pseudorandom numbers in multithreaded programs structured using fork-join parallelism. No locking or synchronization is required (other than the usual memory fence immediately after object creation). Because the generate method has no loops or conditionals, it is suitable for SIMD or GPU implementation. We derive SPLITMIX from the DOTMIX algorithm of Leiserson, Schardl, and Sukha by making a series of program transformations and engineering improvements. The end result is an object-oriented version of the purely functional API used in the Haskell library for over a decade, but SPLITMIX is faster and produces pseudorandom sequences of higher quality;it is also far superior in quality and speed to java util. Random, and has been included in Java JDK8 as the class j ava. util. SplittableRandom. We have tested the pseudorandom sequences produced by SPLITMIX using two standard statistical test suites (DieHarder and TestU01) and they appear to be adequate for "everyday" use, such as in Monte Carlo algorithms and randomized data structures where speed is important.

关键词： Algorithms Performance collections determinism Java multithreading nondeterminism object-oriented parallel computing pedigree pseudorandom random number generator recursive splitting Scala spliterator splittable data structures streams

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