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Dalvik VM - Deep dive into what makes the Android apps run
Dalvik VM - Deep dive into what makes the Android apps run
Published: 2013/12/10
Channel: HasGeek TV
Android Power User: What is the Dalvik VM? What is the Dalvik Cache?
Android Power User: What is the Dalvik VM? What is the Dalvik Cache?
Published: 2012/09/19
Channel: Pocketnow
Dalvik Virtual Machine Android
Dalvik Virtual Machine Android
Published: 2014/11/08
Channel: LearningKart
Run Android Apps on iPad 2 using Alien Dalvik 2 0
Run Android Apps on iPad 2 using Alien Dalvik 2 0
Published: 2011/10/11
Channel: zaone ro
Xamarin vs Dalvik: start up time
Xamarin vs Dalvik: start up time
Published: 2014/03/05
Channel: Egor Bogatov
Android Basics 101: Understanding ART, the Android Runtime
Android Basics 101: Understanding ART, the Android Runtime
Published: 2014/02/12
Channel: xdadevelopers
Android Programming Course - Chapter 2 - The Dalvik VM
Android Programming Course - Chapter 2 - The Dalvik VM
Published: 2013/10/22
Channel: Learn By The Byte
Upgrading from Dalvik to ART on a Nexus 5
Upgrading from Dalvik to ART on a Nexus 5
Published: 2013/11/14
Channel: John Miller
Myriad Alien Dalvik Demo, Q&A
Myriad Alien Dalvik Demo, Q&A
Published: 2011/02/15
Channel: Steve Paine
Samsung Galaxy S5 - Dalvik vs ART
Samsung Galaxy S5 - Dalvik vs ART
Published: 2014/04/22
Channel: Chris Nacca
Download JavaFX-Dalvik Runtime
Download JavaFX-Dalvik Runtime
Published: 2014/09/26
Channel: Andr.oid Eric
Switching to ART from Dalvik
Switching to ART from Dalvik
Published: 2014/03/20
Channel: Ryan Ferguson
Dalvik VM - Deep dive into what makes the Android apps run - Preview video by Satyam
Dalvik VM - Deep dive into what makes the Android apps run - Preview video by Satyam
Published: 2013/11/25
Channel: HasGeek TV
Dalvik Apps Introduction
Dalvik Apps Introduction
Published: 2015/01/05
Channel: Dalvik Apps
Understanding Android Run Time, Dalvik and APK
Understanding Android Run Time, Dalvik and APK
Published: 2016/05/11
Channel: Why Android
What is cache & dalvik cache? How does it work in android?
What is cache & dalvik cache? How does it work in android?
Published: 2015/05/04
Channel: Dhananjay Bhosale
Debugging Android Dalvik and native code seamlessly with JEB
Debugging Android Dalvik and native code seamlessly with JEB
Published: 2016/02/13
Channel: JEB Decompiler
Myriad Alien Dalvik Demo 2.0
Myriad Alien Dalvik Demo 2.0
Published: 2011/10/10
Channel: myriadgroupmarketing
Android Application Security Demo: Dalvik bytecode reverse engineering (Flappy Bird clone)
Android Application Security Demo: Dalvik bytecode reverse engineering (Flappy Bird clone)
Published: 2014/06/10
Channel: Licel
First "In-The-Box" Project demo: Dalvik running on iOS!
First "In-The-Box" Project demo: Dalvik running on iOS!
Published: 2011/05/24
Channel: InTheBoxProject
Android in 60 Seconds   Dalvik
Android in 60 Seconds Dalvik
Published: 2012/04/03
Channel: Kophes
22 How to use Dalvik Debug Monitor Server DDMS - Android App Development Tutorial For Dummies
22 How to use Dalvik Debug Monitor Server DDMS - Android App Development Tutorial For Dummies
Published: 2015/06/15
Channel: Harsha S Srinivas
chC4 - Android Runtime - The Dalvik Virtual Machine
chC4 - Android Runtime - The Dalvik Virtual Machine
Published: 2010/12/11
Channel: android bracu
#9 DVM (Dalvik Virtual Machine) - Android Development (in Tamil)
#9 DVM (Dalvik Virtual Machine) - Android Development (in Tamil)
Published: 2015/12/08
Channel: Collectiva Knowledge Academy
Conversion to Dalvik format failed Error
Conversion to Dalvik format failed Error
Published: 2014/09/13
Channel: Coming Soon
اندرويد دالفك ضد اي ار تي !؟ dalvik vs A.R.T
اندرويد دالفك ضد اي ار تي !؟ dalvik vs A.R.T
Published: 2014/10/04
Channel: Dargooz
Dalvik vs JVM by Oleg Novosad (Ukr)
Dalvik vs JVM by Oleg Novosad (Ukr)
Published: 2015/02/13
Channel: Pacemaker Conference
Diferencias técnicas entre ART y Dalvik - ¿Como funciona Android?
Diferencias técnicas entre ART y Dalvik - ¿Como funciona Android?
Published: 2015/02/17
Channel: latincoder
Que es el Dalvik Cache y como eliminarlo
Que es el Dalvik Cache y como eliminarlo
Published: 2014/03/27
Channel: ConsejosAndroid
Dalvik vs Fogware vs Art - Amark
Dalvik vs Fogware vs Art - Amark
Published: 2014/10/12
Channel: Fogware demo
Resolve Conversion To Dalvik Format Failed With Error
Resolve Conversion To Dalvik Format Failed With Error
Published: 2015/12/19
Channel: Indragni Soft Solutions
ART vs Dalvik: Explained - Android Galaxy Greece
ART vs Dalvik: Explained - Android Galaxy Greece
Published: 2014/02/09
Channel: Andreas Stefanou
Myriad Alien Dalvik Demo
Myriad Alien Dalvik Demo
Published: 2011/04/30
Channel: thehandheldsite
Dalvik Cache clean with Titanium Backup
Dalvik Cache clean with Titanium Backup
Published: 2014/10/18
Channel: Michael Lange
Dalvik Vs Art en #androidIO
Dalvik Vs Art en #androidIO
Published: 2014/04/17
Channel: DesarrolloWeb.com
"Conversion to Dalvik format failed with error 1" in eclipse
"Conversion to Dalvik format failed with error 1" in eclipse
Published: 2015/03/29
Channel: Videos Adda
Patching the dalvik-cache for privilege escalation
Patching the dalvik-cache for privilege escalation
Published: 2013/07/24
Channel: Jon 'jcase' Sawyer
Running Android Apps on the iPad with Myriad
Running Android Apps on the iPad with Myriad's Alien Dalvik
Published: 2013/11/17
Channel: Follow the science and technology
Dalvik vs ART comparison on antutu benchmark (MOTO G)
Dalvik vs ART comparison on antutu benchmark (MOTO G)
Published: 2014/02/27
Channel: jayank khurana
Myriad Alien Dalvik.mp4
Myriad Alien Dalvik.mp4
Published: 2011/02/09
Channel: SmartphoneLeaks
الفرق بين ART و Dalvik | هل غير ART في اندرويد ؟
الفرق بين ART و Dalvik | هل غير ART في اندرويد ؟
Published: 2015/04/18
Channel: Rajab Izzadeen
InsDal
InsDal
Published: 2016/12/03
Channel: 刘洁瑞
LCU14-100: Dalvik is Dead, Long Live Dalvik! OR Tuning ART
LCU14-100: Dalvik is Dead, Long Live Dalvik! OR Tuning ART
Published: 2014/09/15
Channel: Linaro OnAir
ART vs. Dalvik (Lollipop vs Kitkat) galaxy s5 benchmark 1080p
ART vs. Dalvik (Lollipop vs Kitkat) galaxy s5 benchmark 1080p
Published: 2015/08/27
Channel: gamer30168
Activar opciones desarrollador. Cambiar Dalvik por ART y mejorar la velocidad de Android
Activar opciones desarrollador. Cambiar Dalvik por ART y mejorar la velocidad de Android
Published: 2014/05/19
Channel: Juan Cascón Baños
Dalvik VM   Deep dive into what makes the Android apps run clip4
Dalvik VM Deep dive into what makes the Android apps run clip4
Published: 2014/09/30
Channel: HUONG 07
How to fix Lucky Patcher LVL lollipop Samsung 5.0 clear Dalvik cache not working LVL not working
How to fix Lucky Patcher LVL lollipop Samsung 5.0 clear Dalvik cache not working LVL not working
Published: 2017/07/04
Channel: fredyfrankle1
Experimenta sustituir Dalvik por ART para mejorar el rendimiento en Android 4.4 KitKat (Tutorial)
Experimenta sustituir Dalvik por ART para mejorar el rendimiento en Android 4.4 KitKat (Tutorial)
Published: 2013/12/06
Channel: DavBar9
Speed up Nexus 5 with Moto X Dalvik Optimizations [Android 4.4 KitKat]
Speed up Nexus 5 with Moto X Dalvik Optimizations [Android 4.4 KitKat]
Published: 2013/11/22
Channel: AppReviewBros
Enable/Disable Art/Dalvik Android 4.4.4
Enable/Disable Art/Dalvik Android 4.4.4
Published: 2014/09/06
Channel: IT ADV
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WIKIPEDIA ARTICLE

From Wikipedia, the free encyclopedia
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Dalvik
Original author(s) Dan Bornstein
Operating system Linux kernel
Platform Android
Type Virtual machine
License Apache License 2.0
Website source.android.com/devices/tech/dalvik/index.html
Dalvik Executable
Filename extension .dex

Dalvik is a discontinued[1] process virtual machine (VM) in Google's Android operating system that executes applications written for Android. Dalvik is an integral part of the Android software stack in Android versions 4.4 "KitKat" and earlier, which is typically used on mobile devices such as mobile phones and tablet computers, and more recently on devices such as smart TVs and wearables. Dalvik is open-source software, originally written by Dan Bornstein, who named it after the fishing village of Dalvík in Eyjafjörður, Iceland.[2][3]

Programs for Android are commonly written in Java and compiled to bytecode for the Java virtual machine, which is then translated to Dalvik bytecode and stored in .dex (Dalvik EXecutable) and .odex (Optimized Dalvik EXecutable) files; related terms odex and de-odex are associated with respective bytecode conversions. The compact Dalvik Executable format is designed for systems that are constrained in terms of memory and processor speed.

The successor of Dalvik is Android Runtime (ART), which uses the same bytecode and .dex files (but not .odex files), with the succession aiming at performance improvements transparent to the end users. The new runtime environment was included for the first time in Android 4.4 "KitKat" as a technology preview,[4][5] and replaced Dalvik entirely in later versions; Android 5.0 "Lollipop" is the first version in which ART is the only included runtime.[6]

Architecture[edit]

A comparison of Dalvik and ART architectures

Unlike Java VMs, which are stack machines, the Dalvik VM uses a register-based architecture that requires fewer, typically more complex, virtual machine instructions. Dalvik programs are written in Java using the Android application programming interface (API), compiled to Java bytecode, and converted to Dalvik instructions as necessary.

A tool called dx is used to convert Java .class files into the .dex format. Multiple classes are included in a single .dex file. Duplicate strings and other constants used in multiple class files are included only once in the .dex output to conserve space. Java bytecode is also converted into an alternative instruction set used by the Dalvik VM. An uncompressed .dex file is typically a few percent smaller in size than a compressed Java archive (JAR) derived from the same .class files.[7]

The Dalvik executables may be modified again when installed onto a mobile device. In order to gain further optimizations, byte order may be swapped in certain data, simple data structures and function libraries may be linked inline, and empty class objects may be short-circuited, for example.

Being optimized for low memory requirements, Dalvik has some specific characteristics that differentiate it from other standard VMs:[8]

  • The VM was slimmed down to use less space.
  • The constant pool has been modified to use only 32-bit indices to simplify the interpreter.
  • Standard Java bytecode executes 8-bit stack instructions. Local variables must be copied to or from the operand stack by separate instructions. Dalvik instead uses its own 16-bit instruction set that works directly on local variables. The local variable is commonly picked by a 4-bit "virtual register" field. This lowers Dalvik's instruction count and raises its interpreter speed.

According to Google, the design of Dalvik permits a device to run multiple instances of the VM efficiently.[9]

Android 2.2 "Froyo" brought trace-based just-in-time (JIT) compilation into Dalvik, optimizing the execution of applications by continually profiling applications each time they run and dynamically compiling frequently executed short segments of their bytecode into native machine code. While Dalvik interprets the rest of application's bytecode, native execution of those short bytecode segments, called "traces", provides significant performance improvements.[10][11][12]

Performance[edit]

A Dalvik-powered phone

The relative merits of stack machines versus register-based approaches are a subject of ongoing debate.[13]

Generally, stack-based machines must use instructions to load data on the stack and manipulate that data, and, thus, require more instructions than register machines to implement the same high-level code, but the instructions in a register machine must encode the source and destination registers and, therefore, tend to be larger. This difference is of importance to VM interpreters, for which opcode dispatch tends to be expensive, along with other factors similarly relevant to just-in-time compilation.

Tests performed on ARMv7 devices in 2010 by Oracle (owner of the Java technology) with standard non-graphical Java benchmarks showed the HotSpot VM of Java SE embedded to be 2–3 times faster than the JIT-based Dalvik VM of Android 2.2 (the initial Android release that included a JIT compiler).[14] In 2012, academic benchmarks confirmed the factor of 3 between HotSpot and Dalvik on the same Android board, also noting that Dalvik code was not smaller than Hotspot.[15]

Furthermore, as of March 2014, benchmarks performed on an Android device still show up to a factor 100 between native applications and a Dalvik application on the same Android device.[16][original research?][improper synthesis?] Upon running benchmarks using the early interpreter of 2009, both Java Native Interface (JNI) and native code showed an order of magnitude speedup.[17]

Licensing and patents[edit]

Dalvik is published under the terms of the Apache License 2.0.[18] Google says that Dalvik is a clean-room implementation rather than a development on top of a standard Java runtime, which would mean it does not inherit copyright-based license restrictions from either the standard-edition or open-source-edition Java runtimes.[19] Oracle and some reviewers dispute this.[20]

On August 12, 2010, Oracle, which acquired Sun Microsystems in April 2009 and therefore owns the rights to Java, sued Google over claimed infringement of copyrights and patents. Oracle alleged that Google, in developing Android, knowingly, directly and repeatedly infringed Oracle's Java-related intellectual property.[21][22][23] In May 2012, the jury in this case found that Google did not infringe on Oracle's patents, and the trial judge ruled that the structure of the Java APIs used by Google was not copyrightable.[24][25] The parties agreed to zero dollars in statutory damages for 9 lines of copied code.[26][27]

See also[edit]

References[edit]

  1. ^ "Debugging ART Garbage Collection". Retrieved 6 October 2015. The Dalvik runtime is no longer maintained or available [in latest versions of Android] and its byte-code format is now used by ART. 
  2. ^ Journal entry referencing the source of the name
  3. ^ "Google Calling: Inside Android, the gPhone SDK". onlamp.com. Retrieved 2008-02-05. 
  4. ^ Sean Buckley (2013-11-06). "'ART' experiment in Android KitKat improves battery life and speeds up apps". Engadget. Retrieved 2014-07-05. 
  5. ^ Daniel P. (2013-11-07). "Experimental Google ART runtime in Android KitKat can bring twice faster app executions". phonearena.com. Retrieved 2014-07-05. 
  6. ^ Brad Linder (October 15, 2014). "What's new in Android 5.0 Lollipop?". liliputing.com. Retrieved October 15, 2014. 
  7. ^ Bornstein, Dan (2008-05-29). "Presentation of Dalvik VM Internals" (PDF). Google. p. 22. Retrieved 2010-08-16. 
  8. ^ Rose, John (2008-05-31). "with Android and Dalvik at Google I/O". Retrieved 2008-06-08. 
  9. ^ Google (2009-04-13). "What is Android?". Retrieved 2009-04-19. 
  10. ^ Ben Cheng; Bill Buzbee (May 2010). "A JIT Compiler for Android's Dalvik VM" (PDF). android-app-developer.co.uk. Google. pp. 5–14. Retrieved March 18, 2015. 
  11. ^ Phil Nickinson (May 26, 2010). "Google Android developer explains more about Dalvik and the JIT in Froyo". androidcentral.com. Retrieved July 8, 2014. 
  12. ^ "Nexus One Is Running Android 2.2 Froyo. How Fast Is It Compared To 2.1? Oh, Only About 450% Faster". 2010-05-13. Retrieved 2010-05-21. 
  13. ^ Shi, Yunhe; Gregg, David; Beatty, Andrew; Ertl, M. Anton (2005-06-11). "Virtual Machine Showdown: Stack Versus Registers" (PDF). Retrieved 2009-12-22. 
  14. ^ Vandette, Bob (2010-11-22). "Java SE Embedded Performance Versus Android 2.2". Oracle Corporation. Retrieved 2011-09-04. The results show that although Androids new JIT is an improvement over its interpreter only implementation, Android is still lagging behind the performance of our Hotspot enabled Java SE Embedded. As you can see from the above results, Java SE Embedded can execute Java bytecodes from 2 to 3 times faster than Android 2.2. 
  15. ^ Hyeong-Seok Oh; Beom-Jun Kim; Hyung-Kyu Choi; Soo-Mook Moon (2012). "Evaluation of Android Dalvik virtual machine". Association for Computing Machinery. Retrieved 2014-03-23. In the JITC mode, however, Dakvik is slower than HotSpot by more than 2.9 times and its generated code size is not smaller than HotSpot's due to its worse code quality and trace-chaining code. 
  16. ^ "Top AndEBench Scores". www.eembc.org. Retrieved 2014-03-23. 
  17. ^ "Developing and Benchmarking Native Linux Applications on Android". Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering. Springer Publishing. 2009-04-29. Retrieved 2014-03-23. The results show that native C applications can be up to 30 times as fast as an identical algorithm running in Dalvik VM. Java applications can become a speed-up of up to 10 times if utilizing JNI. 
  18. ^ "Downloading the Source Tree - Android Open Source". Android.git.kernel.org. Archived from the original on 2009-04-17. Retrieved 2012-06-07. 
  19. ^ Stefano Mazzocchi (2007-11-12). "Dalvik: how Google routed around Sun’s IP-based licensing restrictions on Java ME". Archived from the original on 2011-02-25. Retrieved 2010-08-16. 
  20. ^ Ed Bott (September 8, 2011). "The real history of Java and Android, as told by Google". ZDNet. Retrieved 2011-11-27. The definition of a “clean room” implementation is that the engineers writing the code have no direct exposure to the original, copyrighted material, including code, specifications, and other documentation. That’s a problem for Google, as I noted in yesterday’s post, because there is substantial evidence that the engineers working on the project had direct access to the copyrighted material.  
  21. ^ "Oracle Sues Google Over Java in Android Devices". digitaltrends.com. 2010-08-13. Retrieved 2011-08-08. 
  22. ^ James Niccolai (2010-08-12). "Oracle sues Google over Java use in Android". Computerworld. Retrieved 2010-08-13. 
  23. ^ Mark Hachman (2010-08-13). "Oracle Sues Google Over Android Java Use". PC Magazine. Ziff Davis. 
  24. ^ Josh Lowensohn (May 23, 2012). "Jury clears Google of infringing on Oracle's patents". ZDNet. Retrieved 2012-05-25. 
  25. ^ Joe Mullin (May 31, 2012). "Google wins crucial API ruling, Oracle’s case decimated". Ars Technica. Retrieved 2012-06-01. 
  26. ^ Niccolai, James (June 20, 2012). "Oracle agrees to 'zero' damages in Google lawsuit, eyes appeal". Retrieved 2012-06-23. 
  27. ^ Adam Outler (May 16, 2012). "Update on the Oracle Versus Google Trial". Retrieved 2013-01-18. A major portion of the Oracle’s claims are based on 9 lines of code contained within Java.Util.Arrays.rangeCheck(). Here is the code in question:... 

External links[edit]

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