64-Bit Support

ART was designed in mind with modularity of the various target architectures in which it is supposed to run on. As such, it provides a multitude of compiler-backends targeting today’s most common architectures such as ARM, x86 and MIPS. In addition, 64-bit support for ARM64, x86-64 and while still not implemented, also MIPS64.

While we have gone more in depth of the advantages and implications of switching over to 64-bit architectures in the iPhone 5s review, the main points to take away are the availability of an increased address space, generally increased performance, and vastly increased cryptographic capabilities and performance, all while maintaining full 32-bit compatibility with all existing apps.

An important difference that Google is applying over Apple, at least inside VM runtime applications, is that they are using reference compression to avoid the usual memory bloat that comes with the switch to 64-bit. The VM retains simple 32-bit references.

Google has made available some preview benchmarks showcasing the performance gains both on x86 and ARM platforms. The x86 benchmarks were executed on a Intel BayTrail system, and show a 2x to 4.5x speedup in various RenderScript benchmarks. On the ARM side, the crypto performance gains over 32-bit were showcased on an A57/A53 system. Both of these are relatively non-representative of one should really expect in real-world use-cases so they’re not that useful as a performance prediction.

However Google also made some interesting numbers available on one of their internal build-systems called Panorama. Here we can see a 13 to 19% increase in performance by simply switching over the ABI. It is also good to see how ARM’s Cortex A53 is able to make a bigger impact on performance when in AArch64 mode than the A57 cores.

Google claims that 85% of all current Play Store apps are immediately ready to switch over to 64 bit - which would mean that only 15% of applications have some kind of native code that needs targeted recompiling by the developer to make use of 64-bit architectures. This is a great win for Google and I expect the shift over to 64-bit to be very fast once silicon vendors start shipping 64-bit SoCs in the coming year.


In many points, Google has delivered its “Performance boosting thing” and addressed much of the shortcomings that have plagued Android for years.

ART patches up many of the Achilles’ heels that comes with running non-native applications and having an automatic memory management system. As a developer, I couldn’t have asked for more, and most performance issues that I needed to work around with clever programming no longer pose such a drastic problem anymore.

This also means that Android is finally able to compete with iOS in terms of application fluidity and performance, a big win for the consumer.

Google still promises to evolve ART in the future and its current state is definitely not what it was 6 months ago, and definitely not what it will be once the L release is made available in its final form in devices. The future looks bright and I can’t wait to see what Google will do with its new runtime.

Garbage Collection: Theory and Practice
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  • phoenix_rizzen - Wednesday, July 2, 2014 - link

    On current Android devices, when you switch the runtime to ART, you get the "Android is upgrading; X of Y" progress bar on first boot. I'm sure once the L release is finalised, it will have a similar UI.

    What's perplexing is why this isn't currently in place on the Dev Preview.
  • tacitust - Thursday, July 3, 2014 - link

    It was probably not high enough on the priority list. Stability comes first, even for previews.
  • NetMage - Tuesday, July 8, 2014 - link

    So, never released then? :)
  • darwinosx - Thursday, July 3, 2014 - link

    They can't and even if they could Apple has nothing to worry about.
  • Alexey291 - Sunday, July 6, 2014 - link

    you're really mad ain't ya :)
  • sprockkets - Tuesday, July 8, 2014 - link

    He's our favorite apple troll. In reality he probably can't even afford to buy an apple ipod, so his mom got one for him.
  • Alexey291 - Wednesday, July 9, 2014 - link

    yup but his arguments are so inane... its almost as if he's paid to do this...
  • Impulses - Wednesday, July 2, 2014 - link

    Seems the rumor is the old Nexus 7 might not see L... It'll be over two years old by the time L arrives officially, and being based on an old Tegra perform that not much else is using anymore it's chances are probably on the low side. I think ART was never enabled as a dev option under KK for it either but don't hold me to that, you can check yourself tho (I've got a 2013, gave my sister a 2012 as a gift tho).
  • uhuznaa - Wednesday, July 2, 2014 - link

    Google has just released the L-sources for the Nexus 7 2012.

    Good update, although I find it interesting that all of a sudden Android after all WAS not as smooth as iOS (which it indeed never was, really).

    What I'm still missing (and I hope L will address this at some point) are more privacy controls. If (stock) Android grows a way to manage permissions after an app is installed I would be very glad.
  • nathanddrews - Wednesday, July 2, 2014 - link

    Yeah, I thought "butter" took care of that.

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