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

[phil at highoctane.be]

Google wants to beat the speed of iOS. iOS uses native code and Objective-C
highly optimized dispatch loop. So, with a less powerful piece of hardware,
Apple devices trounce Android ones when it comes to smoothness of
animations, battery etc.

As Android uses the Dalvik VM, the only way to get as speedy as iOS is to
go as close to native as possible.

We are talking 60 fps for a lot of pixels these days. My Nexus 7 with 4.4.2
still feels laggy compared to my iPad2. That is due to the whole VM/Java
thing. iPad2 is 2-core, Nexus 7 is 4-core and with a NVidia graphics chip.

AOT is working very well when it comes to Java code (well, Android Dalvik
bytecode here).
http://en.wikipedia.org/wiki/AOT_compiler

AOT is getting a lot of traction these days. LLVM also has this.

So, why care about 50% or 100%, the point is that it is getting faster in a
way that affects the user perception. Which is what matters.

For example, Pharo feels slow compared to Dolphin, Smalltalk/X etc. Maybe
the VM is of equivalent speed. Not the user experience.

Phil

On Fri, Dec 13, 2013 at 12:13 AM, Igor Stasenko <siguctua at gmail.com> wrote:

>
>
>
>
> On 12 December 2013 23:57, Eliot Miranda <eliot.miranda at gmail.com> wrote:
>
>>
>>
>>
>>
>> On Thu, Dec 12, 2013 at 2:53 PM, Nicolas Cellier <
>> nicolas.cellier.aka.nice at gmail.com> wrote:
>>
>>>
>>> But he said increase in speed, not performance.
>>>
>>
>> Same argument.  What does it mean to complete a task 100% faster?  What
>> does it mean to reach your destination 100% faster?
>>
>>
> not much apart from the author's lack of literacy :)
>
>
>>
>>>
>>> 2013/12/12 Eliot Miranda <eliot.miranda at gmail.com>
>>>
>>>>
>>>>
>>>>
>>>>
>>>> On Thu, Dec 12, 2013 at 1:23 PM, Nicolas Cellier <
>>>> nicolas.cellier.aka.nice at gmail.com> wrote:
>>>>
>>>>>
>>>>> I would interpret twice as fast, and that's only 50% rather than 100%
>>>>> reduction of execution time :)
>>>>>
>>>>
>>>> relative performance = new time - old time / old time.
>>>> 2x = -50%
>>>> 3x = -75%
>>>> etc
>>>>
>>>> -100% means new time = 0, and performance is infinite.
>>>>
>>>>
>>>>>
>>>>>
>>>>> 2013/12/12 Eliot Miranda <eliot.miranda at gmail.com>
>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Thu, Dec 12, 2013 at 1:08 PM, phil at highoctane.be <
>>>>>> phil at highoctane.be> wrote:
>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> http://m.pocketnow.com/2013/11/13/dalvik-vs-art
>>>>>>>
>>>>>>
>>>>>> "The benefits? Some sources are reporting a 50% increase in speed.
>>>>>> Others say it’s closer to 100%. Many claim they’ve seen their battery life
>>>>>> increase by 25% or more!"
>>>>>>
>>>>>> Got to love those 100% speed increases.  Apps really fly when they
>>>>>> take no time at all...
>>>>>>
>>>>>> --
>>>>>> Eliot
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>> --
>>>> best,
>>>> Eliot
>>>>
>>>>
>>>
>>>
>>
>>
>> --
>> best,
>> Eliot
>>
>>
>
>
> --
> Best regards,
> Igor Stasenko.
>
>
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