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Evaluation of a java Ahead-of-Time Compiler for Embedded Systems

COMPUTER JOURNAL 2012年第2期55卷 232-252页

作者： Jung, Dong-Heon Moon, Soo-Mook Bae, Sung-Hwan Seoul Natl Univ Sch Elect Engn & Comp Sci Seoul 151742 South Korea

java embedded systems often include java middleware classes installed on the client device. For higher performance, they can be compiled into machine code before runtime using an ahead-of-time compiler (AOTC). There are many approaches to AOTC, yet a bytecode-to-C (b-to-C) AOTC which translates the bytecode into the C code and then compiles it using an existing optimizing compiler such as gcc would be the most straightforward one. This paper explores a few important design and optimization issues of a b-to-C AOTC, including the compilation form for the translated C code, the call interfaces among translated and interpreted java methods, and java-specific optimizations by the AOTC that can complement the gcc optimizations. We evaluate these issues with our b-to-C AOTC implemented on the MIPS platform for the Sun's CDC VM to understand their performance impact.

关键词： java ahead-of-time compiler bytecode-to-C embedded systems java virtual machine code optimizations

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Tokenisation and compression of java class files

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JOURNAL OF SYSTEMS ARCHITECTURE 2012年第1期58卷 1-12页

作者： Haggett, Shawn Knowles, Greg Flinders Univ Adelaide Sch Comp Sci Engn & Math Adelaide SA 5046 Australia

Method calls in object oriented languages, such as java, are bound at run-time, making the method binding technique very important for the performance of the language. Efficient implementations can rely on having additional memory and/or processing power available either to store lookup tables or to allow for the construction of caches or rewriting of instructions during runtime. These are luxuries not always available on mobile devices such as mobile phones, tablets, etc. In this paper we describe a novel way of tokenising and compressing method dispatch tables to provide an efficient dispatch process which could be implemented in hardware in only a few operations. We demonstrate this in the context of java, also showing a significant reduction in size for the resulting class files. (C) 2011 Elsevier B.V. All rights reserved.

关键词： java virtual machine Embedded systems J2ME CLDC

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java bytecode verification: Algorithms and formalizations

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JOURNAL OF AUTOMATED REASONING 2003年第3-4期30卷 235-269页

作者： Leroy, X INRIA Rocquencourt Le Chesnay France

Bytecode verification is a crucial security component for java applets, on the Web and on embedded devices such as smart cards. This paper reviews the various bytecode verification algorithms that have been proposed, recasts them in a common framework of dataflow analysis, and surveys the use of proof assistants to specify bytecode verification and prove its correctness.

关键词： bytecode verification java virtual machine dataflow analysis abstract interpretation subroutines

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Using memory compression for energy reduction in an embedded java system

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JOURNAL OF CIRCUITS SYSTEMS AND COMPUTERS 2002年第5期11卷 537-555页

作者： Chen, G Kandemir, M Vijaykrishnan, N Irwin, MJ Penn State Univ Microsyst Design Lab State Coll PA 16802 USA Princeton Univ Dept Elect Engn Princeton NJ 08544 USA

The java programming language is being increasingly used for application development for mobile and embedded devices. Limited energy and memory resources are important constraints for such systems. Compression is an useful and widely employed mechanism to reduce the memory requirements of the system. As the leakage energy of a memory system increases with its size and because of the increasing contribution of leakage to overall system energy, compression also has a significant effect on reducing energy consumption. However, storing compressed data/instructions has a performance and energy overhead associated with decompression at runtime. The underlying compression algorithm, the corresponding implementation of the decompression and the ability to reuse decompressed information critically impact this overhead. In this paper, we explore the influence of compression on overall memory energy using a commercial embedded java virtual machine (JVM) and a customized compression algorithm. Our results show that compression is effective in reducing energy even when considering the runtime decompression overheads for most applications. Further, we show a mechanism that selectively compresses portions of the memory to enhance energy savings. Finally, a scheme for clustering the code and data to,improve the reuse of the decompressed data is presented.

关键词： java virtual machine memory compression leakage energy dynamic energy embedded system

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JESSICA: java-enabled single-system-image computing architecture

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JOURNAL OF PARALLEL AND DISTRIBUTED COMPUTING 2000年第10期60卷 1194-1222页

作者： Ma, MJM Wang, CL Lau, FCM Univ Hong Kong Dept Comp Sci & Informat Syst Hong Kong Hong Kong Peoples R China

JESSICA stands for java-enabled single-system-image computing architecture, a middleware that runs on top of the standard UNIX operating system to support parallel execution of multithreaded java applications in a cluster of computers. JESSICA hides the physical boundaries between machines and makes the cluster appear as a single computer to applications a single system image. JESSICA supports preemptive thread migration, which allows a thread to freely move between machines during its execution, and global object sharing through the help of a distributed shared-memory subsystem. JESSICA implements location-transparency through a message-redirection mechanism. The result is a parallel execution environment where threads are automatically redistributed across the cluster for achieving the maximal possible parallelism. A JESSICA prototype that runs on a Linux cluster has been implemented and considerable speedups have been obtained for all the experimental applications tested. (C) 2000 Academic Press.

关键词： cluster computing single system image dynamic load balancing thread migration java virtual machine JESSICA

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Improving java performance and energy dissipation through efficient code caching

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DESIGN AUTOMATION FOR EMBEDDED SYSTEMS 2009年第3期13卷 179-192页

作者： Sun, Yu Zhang, Wei So Illinois Univ Dept Elect & Comp Engn Carbondale IL 62901 USA

Traditional java code generation and instruction fetch path is not efficient, as java binary code is typically written into the data cache first, and then is loaded into the instruction cache through the shared L2 cache or memory, which takes both time and energy. In this paper, we study three hardware-based code caching strategies, which attempt to write and read the dynamically generated java code faster and more energy-efficiently. Our experimental results indicate that with proper architectural support, writing code directly into the instruction cache can improve the performance for a variety of java applications by 9.6% on average, with up to 42.9%. Also, the average energy dissipation of these java programs can be reduced by 6% with efficient code caching.

关键词： java virtual machine Code caching Performance Energy consumption

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Packer: Parallel Garbage Collection Based on virtual Spaces

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IEEE TRANSACTIONS ON COMPUTERS 2012年第11期61卷 1611-1623页

作者： Liu, Shaoshan Tang, Jie Wang, Ligang Li, Xiao-Feng Gaudiot, Jean-Luc Microsoft Corp Redmond WA 98052 USA Beijing Inst Technol Sch Comp Sci & Technol Beijing Peoples R China Intel China Res Ctr Ltd Managed Runtime Technol Ctr Beijing Peoples R China Intel China Res Ctr Ltd China Runtime Technol Lab Beijing Peoples R China Univ Calif Irvine Dept Elect & Comp Engn Irvine CA 92697 USA

The fundamental challenge of garbage collector (GC) design is to maximize the recycled space with minimal time overhead. For efficient memory management, in many GC designs the heap is divided into large object space (LOS) and normal object space (non-LOS). When either space is full, garbage collection is triggered even though the other space may still have plenty of room, thus leading to inefficient space utilization. Also, space partitioning in existing GC designs implies different GC algorithms for different spaces. This not only prolongs the pause time of garbage collection, but also makes collection inefficient on multiple spaces. To address these problems, we propose Packer, a parallel garbage collection algorithm based on the novel concept of virtual spaces. Instead of physically dividing the heap into multiple spaces, Packer manages multiple virtual spaces in one physical space. With multiple virtual spaces, Packer offers efficient memory management. With one physical space, Packer avoids the problem of an inefficient space utilization. To reduce the garbage collection pause time, we also propose a novel parallelization method that is applicable to multiple virtual spaces. Specifically, we reduce the compacting GC parallelization problem into a discreted acyclic graph (DAG) traversal parallelization problem, and apply it to both normal and large object compaction.

关键词： Garbage collection java virtual machine memory management parallel systems

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Efficient register mapping and allocation in LaTTe, an open-source java just-in-time compiler

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IEEE TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTEMS 2007年第1期18卷 57-69页

作者： Yang, Byung-Sun Lee, Junpyo Lee, Seungll Park, Seongbae Chung, Yoo C. Kim, Suhyun Ebcioglu, Kemal Altman, Erik Moon, Soo-Mook Veloxsoft Inc Seoul 152050 South Korea Seoul Natl Univ Seoul 152050 South Korea Google Inc Mountain View CA 94043 USA Informat & Commun Univ Taejon 305732 South Korea IBM Corp Thomas J Watson Res Ctr Yorktown Hts NY 10598 USA Global Supercomp Corp Yorktown Hts NY 10598 USA Seoul Natl Univ Sch Elect Engn Seoul 151742 South Korea

java just-in-time (JIT) compilers improve the performance of a java virtual machine (JVM) by translating java bytecode into native machine code on demand. One important problem in java JIT compilation is how to map stack entries and local variables to registers efficiently and quickly, since register-based computations are much faster than memory-based ones, while JIT compilation overhead is part of the whole running time. This paper introduces LaTTe, an open-source java JIT compiler that performs fast generation of efficiently register-mapped RISC code. LaTTe first maps "all" local variables and stack entries into pseudoregisters, followed by real register allocation which also coalesces copies corresponding to pushes and pops between local variables and stack entries aggressively. Our experimental results indicate that LaTTe's sophisticated register mapping and allocation really pay off, achieving twice the performance of a naive JIT compiler that maps all local variables and stack entries to memory. It is also shown that LaTTe makes a reasonable trade-off between quality and speed of register mapping and allocation for the bytecode. We expect these results will also be beneficial to parallel and distributed java computing 1) by enhancing single-thread java performance and 2) by significantly reducing the number of memory accesses which the rest of the system must properly order to maintain coherence and keep threads synchronized.

关键词： java virtual machine just-in-time compilation register mapping register allocation copy coalescing

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Scoped types and aspects for real-time java memory management

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REAL-TIME SYSTEMS 2007年第1期37卷 1-44页

作者： Andreae, Chris Coady, Yvonne Gibbs, Celina Noble, James Vitek, Jan Zhao, Tian Purdue Univ W Lafayette IN 47907 USA Victoria Univ Wellington Wellington New Zealand Univ Wisconsin Milwaukee WI 53201 USA Univ Victoria Victoria BC Canada

Real-time systems are notoriously difficult to design and implement, and, as many real-time problems are safety-critical, their solutions must be reliable as well as efficient and correct. While higher-level programming models (such as the Real-Time Specification for java) permit real-time programmers to use language features that most programmers take for granted (objects, type checking, dynamic dispatch, and memory safety) the compromises required for real-time execution, especially concerning memory allocation, can create as many problems as they solve. This paper presents Scoped Types and Aspects for Real-Time Systems (STARS) a novel programming model for real-time systems. Scoped Types give programmers a clear model of their programs' memory use, and, being statically checkable, prevent the run-time memory errors that bedevil the RTSJ. Adopting the integrated Scoped Types and Aspects approach can significantly improve both the quality and performance of a real-time java systems, resulting in simpler systems that are reliable, efficient, and correct.

关键词： real-time systems java virtual machine memory management ownership types

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Client ahead-of-time compiler for embedded java platforms

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SOFTWARE-PRACTICE & EXPERIENCE 2009年第3期39卷 259-278页

作者： Hong, Sunghyun Kim, Jin-Chul Moon, Soo-Mook Shin, Jin Woo Lee, Jaemok Oh, Hyeong-Seok Choi, Hyung-Kyu Seoul Natl Univ Sch Elect Engn & Comp Sci Seoul 151742 South Korea

Many embedded java platforms execute two types of java classes: those installed statically on the client device and those downloaded dynamically from service providers at run time. For achieving higher performance, the static java classes can be compiled into machine code by ahead-of-time compiler (AOTC) in the server, and the translated machine code can be installed on the client device. Unfortunately, AOTC cannot be applicable to the dynamically downloaded classes. This paper proposes client-AOTC (c-AOTC), which performs AOTC on the client device using the just-in-time compiler (JITC) module installed on the device, obviating the JITC overhead and complementing the server-AOTC. The machine code of a method translated by JITC is cached on a persistent memory of the device, and when the method is invoked again in a later run of the program, the machine code is loaded and executed directly without any translation overhead. A major issue in c-AOTC is relocation because sonic of the address constants embedded in the cached machine code are not correct when the machine code is loaded and used in a different run;those addresses should be corrected before they are used. Constant pool resolution and inlining complicate the relocation problem, and we propose our solutions. The persistent memory overhead for saving the relocation information is also an issue, and we propose a technique to encode the relocation information and compress the machine code efficiently. We developed a c-AOTC on Sun's CDC VM reference implementation, and our evaluation results indicate that c-AOTC can improve the performance significantly, as much as an average of 12% for EEMBC and 4% for SpecJVM98, with a persistent memory overhead of 1% on average. Copyright (c) 2008 John Wiley & Sons, Ltd.

关键词： java ahead-of-time compiler just-in-time compiler relocation early binding java virtual machine J2ME CDC

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