[Vm-dev] Re: Dalvik vs. ART: Android virtual machines and the battle for better performance | Pocketnow

Clément Bera bera.clement at gmail.com
Sat Dec 14 08:04:51 UTC 2013


2013/12/13 Eliot Miranda <eliot.miranda at gmail.com>

> On Fri, Dec 13, 2013 at 1:07 PM, askoh <askoh at askoh.com> wrote:
>> I am not a VM guy. But, is the Smalltalk in a C World article compiling
>> Smalltalk to machine code to run without the VM?
>> http://www.cl.cam.ac.uk/~dc552/papers/SmalltalkInACWorld.pdf
>> He talks about the VM being a relic of the past. Is that true?
> Is the Java VM a relic of the past?  Given portable devices is compiled
> code a relic of the past?  Is a safe development environment with fast
> compile times a thing of the past?  Their own conclusions imply that the
> answer is not yet:

What do you mean by not yet ? Do you think that in a 10 or 20 years VMs
will be obsolete ?

There's 1 detail I am not sure. By JIT in this article (
http://m.pocketnow.com/2013/11/13/dalvik-vs-art), does he mean the bytecode
to native code generator only or the native code generator + inline cache
management + adaptive recompiler.

I'm wondering, even if they have their code stored as native code instead
of byte code, do they have some kind of native code generator for adaptive
recompilation to reach such a performance ?

And how do they manage their inline caches ? As all methods are native,
some monomorphic inline caches could be promoted to PIC due to 1 very rare
case and then as they always keep the same n-code this send site would be
slower forever. Does this mean they would need to empty inline caches
sometimes ?

> "Our current approach lacks some of the advantages of Smalltalk. The most
> obvious of these is debugging. Our current implementation emits very sparse
> DWARF debugging information and so is fairly limited in terms of debugging
> support even in comparison to C, and therefore a long way behind the state
> of the art for Smalltalk circa 1980. This is currently the focus of ongoing
> work. Once this is done, then implementing things like thisContext making
> use of debug metadata become possible. In our current implementation,
> run-time introspection is only available for objects and variables bound to
> blocks, not for activation records.
> Closely related is the rest of the IDE. In traditional Smalltalk
> implementations, the IDE is closely integrated with the execution
> environment. GNU Smalltalk is the major exception, and provides a model
> close to ours. Building a good IDE and debugger is beyond the scope of the
> LanguageKit project, but building these tools on top of LanguageKit is a
> goal of E ́toile ́."
>> All the best,
>> Aik-Siong Koh
>> --
>> View this message in context:
>> http://forum.world.st/Dalvik-vs-ART-Android-virtual-machines-and-the-battle-for-better-performance-Pocketnow-tp4729727p4729982.html
>> Sent from the Squeak VM mailing list archive at Nabble.com.
> --
> best,
> Eliot
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.squeakfoundation.org/pipermail/vm-dev/attachments/20131214/d6b75206/attachment-0001.htm

More information about the Vm-dev mailing list