• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.11B
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• pp.1323-1328
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• 2011

In this paper, we have shown Dalvik virtual machine implementation to reduce the profiling overhead from the trace of the JIT compiler for the specific method. By running the same Java method on the original Dalvik VM and the modified Dalvik VM, we have achieved around 30% performance improvement with this algorithm. In this paper, to increase the reader's understanding of Android Dalvik virtual machine, we will explain the architecture of Dalvik JIT compiler and we will provide the detailed explanation with source codes for modified parts of Dalvik virtual machine. From the industry perspective, we can expect competitive benefits over the competitors with performance improvement in Android core.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.04a
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• pp.45-46
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• 2012

현재 스마트폰에서 가장 널리 쓰이는 OS는 안드로이드이다. 안드로이드는 오픈 소스 플랫폼이기 때문에 이를 수정하여 기존 기술을 개선하거나 새로운 기술을 개발하려는 시도가 많이 이루어지고 있다. 이를 위해 필수적으로 시행해야 할 것이 Dalvik Virtual Machine을 분석하는 작업이다. 이에, 본 연구는 Dalvik Virtual Machine의 주요 요소를 분석하였다.

• ETRI Journal
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• v.37 no.5
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• pp.1001-1011
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• 2015

Since just-in-time (JIT) has considerable overhead to detect hot spots and compile them at runtime, using sophisticated optimization techniques for embedded devices means that any resulting performance improvements will be limited. In this paper, we introduce a novel static Dalvik bytecode optimization framework, as a complementary compilation of the Dalvik virtual machine, to improve the performance of Android applications. Our system generates optimized Dalvik bytecodes by using Low Level Virtual Machine (LLVM). A major obstacle in using LLVM for optimizing Dalvik bytecodes is determining how to handle the high-level language features of the Dalvik bytecode in LLVM IR and how to optimize LLVM IR conforming to the language information of the Dalvik bytecode. To this end, we annotate the high-level language features of Dalvik bytecode to LLVM IR and successfully optimize Dalvik bytecodes through instruction selection processes. Our experimental results show that our system with JIT improves the performance of Android applications by up to 6.08 times, and surpasses JIT by up to 4.34 times.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.1
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• pp.486-492
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• 2011

In this paper we analyzed performance of Andriod's Davik virtual machine(VM) using standard benchmark and compared the result with the embedded Java virtual machine. We used a well known benchmark suit named SPECJVM for the measurement. For the fair comparison, Sun Java embedded JVM is ported and the same benchmark is ported on it. The Odriod smartphone hardware platform is used as the target hardware. We have added a Just-In-Time compiler to Dalvik, which is not supported in the recent Android release, and measured performance improvement. The experiment result show that Dalvik achieved 15% and Dalvik with JIT shows 63% of the Sun's JVM performance.

• Proceedings of the Korean Information Science Society Conference
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• 2010.11a
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• pp.149-150
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• 2010

• Proceedings of the Korean Information Science Society Conference
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• 2011.06a
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• pp.570-573
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• 2011

Dalvik 가상 머신은 최적화가 쉽지 않았던 스택 기반의 가상 머신인 자바 가상 머신(JVM)과 달리 레지스터 기반의 가상 머신이므로 여러 최적화 기법을 적용할 수 있다. 따라서 Dalvik 가상 머신을 위한 새로운 레지스터 할당기법이 필요하다. 본 논문에서는 dx tool을 거친 레지스터 기반의 Dalvik byte code를 레지스터 재 할당하여 최적화하고, 이를 Dalvik JIT으로 보내어 다시 한번 레지스터 재할당 함으로써 최적화 효율을 높일 수 있는 최적화 기법을 제안하였다. 또한 제안 기법과 Dalvik JIT의 복잡도를 비교함으로써 제안기법을 검증하였다.

• IEIE Transactions on Smart Processing and Computing
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• v.4 no.3
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• pp.169-172
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• 2015

Dalvik is a virtual machine (VM) that is designed to run Java-based Android applications. A trace-based just-in-time (JIT) compilation technique is currently employed to improve performance of the Dalvik VM. However, due to runtime compilation overhead, the trace-based JIT compiler provides only a few simple optimizations. Moreover, because each trace contains only a few instructions, the trace-based JIT compiler inherently exploits fewer optimization and parallelization opportunities than a method-based JIT compiler that compiles method-by-method. So we propose a new method-based JIT compiler, named DEX2C, in order to improve performance by finding more opportunities for both optimization and parallelization in Android applications. We employ C code as an intermediate product in order to find more optimization opportunities by using the GNU C Compiler (GCC), and we will detect parallelism by using the Intel C/C++ parallel compiler and the AESOP compiler in our future work. In this paper, we introduce our DEX2C compiler, which dynamically translates Dalvik bytecodes (DEX) into C code with method granularity. We also describe a new method-based JIT interface in the Dalvik VM for the DEX2C compiler. Our experiment results show that our compiler and its interface achieve significant performance improvement by up to 15.2 times and 3.7 times on average, in Element Benchmark, and up to 2.8 times for FFT in Smartbench.

• Proceedings of the Korean Information Science Society Conference
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• 2010.11a
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• pp.177-178
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• 2010

• Proceedings of the Korean Information Science Society Conference
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• 2010.11a
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• pp.141-142
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• 2010

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.6
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• pp.231-236
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• 2013

Recently, to improve the user response times of Android applications, several studies have been proposed to combine the idea of Ahead-of-Time compilation into Dalvik virtual machine, which uses Just-in-Time compilation. The studies, however, require modifications of the Dalvik executables of target applications, thus are difficult to be adopted for legacy applications already deployed. This paper proposes a JITwP(JIT with Precompile) technique that precompiles hot traces at application launch time with no modification of the Dalvik executable. It improves the user response times of target applications by providing precompile hints prepared offline. Our experimental results demonstrate a 4% improvement in terms of execution time for the Web browser application.