难道Android的阉割ARM的Jazelle技术？ [英] Does Android castrate the ARM's Jazelle technology?

问题描述

这是我见过的我们应该说Bastardizing的理由了Java字节codeS在Android中是性能。 （我怀疑还有另外一个原因。）但是通过改变字节codeS没有他们做了硬件加速技术，如支持Jazelle没有实际意义，因而实际上降低了性能可用于移动Java平台？

The justification that I've seen for shall we say "Bastardizing" the Java bytecodes in Android was performance. (I suspect there is another reason.) However by changing the byte codes haven't they made hardware acceleration technologies such as Jazelle moot, and thus actually degraded the performance available for a Mobile Java platform?

据了解，该目标平台是一个基于ARM的移动平台似乎直觉上我。虽然它可能给你的其他CPU架构更好的表现似乎在ARM和支持Jazelle的脸上吐。

It appears counter intuitive to me knowing that the target platform is a ARM based mobile platform. While it MIGHT give you better performance on other CPU architectures it seems to spit in the face of ARM and Jazelle.

它有对Java性能什么样的定量影响？

What sort of quantitative effect does it have on Java performance?

它实际上提高性能，如果又如何？

Does it actually improve performance, and if so how?

什么是在其他平台上的效果？ （即X86，MIPS，yadda，yadda，yadda ...）

What's the effect on other platforms? (i.e. x86,mips,yadda,yadda,yadda...)

推荐答案

是的Dalvik做的Jazelle没用。唯一的问题是是的Jazelle有用的开始，或者是90％的营销炒作？一个好的JIT或AOT（提前）编译器往往给更好的表现比尝试使用专门的说明。 Dalvik的名册为基础的方法可能比传统的Java字节code除preTER更快，但如果未成年人是一个跨preTER和一个JIT之间的差异。希望机器人的下一版本中的一个具有JIT

Yes Dalvik makes Jazelle useless. The only question is was Jazelle useful to begin with or is it 90% marketing hype? A good JIT or AOT(ahead of Time) compiler tends to give much better performance than trying to use specialized instructions. The register based approach of Dalvik might be faster than a traditional java bytecode interpreter but if the difference in minor between that of an interpreter and that of a JIT. Hopefully one of the next versions of Android has a JIT.

这需要〜5 - 10年写一个好的虚拟机与艺术的垃圾收集器和优化的状态。太阳（和Microsoft）花了这些年。谷歌也没有。希望他们将继续投资IT这样一天的Andr​​oid的Java code不是较慢的90％，比它应该是。

It takes ~5-10 years to write a good virtual machine with state of the art garbage collectors and optimizers. Sun (and Microsoft) have spent those years. Google hasn't. Hopefully they will keep investing in it so that one day Android Java code isn't a 90% slower than it should be.

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