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Why Arm Is Making All Cortex-A Mobile Cores 64-bit Only

Move will help Arm partners deliver greater security alongside performance gains of up to 20 percent for faster app loading times and better user experiences

David Whaley Headshot
Posted on 25th May 2021 By David Whaley, Director, Strategic Partnerships, Client Line of Business, Arm
Mobile Devices
Reading Time: 5 mins
Why Arm Is Making All Cortex-A Mobile Cores 64-bit Only

As part of today’s Total Compute Solutions launch, we are announcing that all Arm Cortex-A CPU mobile cores will be 64-bit only from 2023.

In order to deliver the best possible processors for the next generation of mobile devices, Arm is transitioning both “big” and “LITTLE” CPU mobile cores to 64-bit. This move will help our partners deliver greater performance and more security features, with 64-bit only mobile devices expected to arrive by 2023.

Arm’s big.LITTLE architecture, launched in 2011, couples power efficient processor cores (“LITTLE”) with more performant cores (“big”) to deliver mobile devices with long battery life, yet have the performance to deliver immersive experiences when required.

The big.LITTLE architecture then evolved with the introduction of DynamIQ technology that combines “big” and “LITTLE” CPUs into a single, fully integrated cluster, resulting in new and enhanced power and performance benefits. More recently, this has been accelerated further with the introduction of Armv9 CPU architecture.

64-bit brings performance and security benefits

The 64-bit instruction set featured in the Armv9 CPU architecture provides the compute performance and capabilities to make common mobile usage faster and more responsive, with performance gains of up to 20 percent for faster app loading times and better user experiences.

It also meets the growing demands of new compute-intensive workloads such as artificial intelligence (AI), Augmented Reality (AR), Virtual Reality (VR) and high-fidelity gaming. One reason is because 64-bit CPUs can fetch, move, and process larger chunks of data within a smaller interval of time than a 32-bit processor, resulting in better performance.

The 64-bit architecture also offers enhanced security through features such as MTE (or Memory Tagging Extensions) which is used to detect common programmer errors when dealing with memory and prevent the most common memory safety vulnerabilities afflicting the mobile ecosystem. Hardware and software-based security features are adopted and enhanced as part of the new Armv9 CPUs to further benefit device security.

64-bit now everywhere

The number of 32-bit mobile devices have been in decline since 64-bit capable mobile Android devices first appeared in 2014. Today, we estimate just over two percent of all mobile devices worldwide remain 32-bit only.

A wide majority of today’s Android devices deploy a version of the OS (version 5.0 and above) capable of simultaneously supporting both 64 and 32-bit Android runtimes, but that comes at a cost of additional memory, development, and testing.

Prioritizing 64-bit application development allows the Android ecosystem to focus on supporting newer features and technologies, with advanced performance and robustness not possible in the 32-bit architecture. This also permits an eventual transition to more modern and future-looking 64-bit only devices.

Influencing the global ecosystem

A major enabler behind the transition of Android applications to support 64-bit architectures is Google. The Google Play store started the 64-bit Android transition by mandating any new apps or updates to current Play apps must provide 64-bit versions.

Additionally, beginning in August 2021, Google Play will stop serving 32-bit apps to 64-bit capable mobile devices, meaning 32-bit apps will no longer be visible to 64-bit capable mobile devices within the Play store.

This does not mean 32-bit apps are going away but addressing the entire Android device market will require that a developer provides 64-bit versions of their apps.

64-bit Android: Progress in China

This activity towards wider support of 64-bit has been filtering through to other global markets. In China, five of the top app stores – Xiaomi, OPPO, vivo, Tencent, and Baidu – recently co-announced their support for migrating the Android ecosystem to 64-bit.  Several of these partners went even further and stated all applications published to their stores need to be 64-bit compliant by the end of 2021.

This will ensure that applications are 64-bit capable and ready to take advantage of the performance and security benefits that the 64-bit architecture provides. This shows that the China ecosystem is largely consistent with the global ecosystem of supporting more 64-bit Android apps to get ready for 64-only devices.

If they have not already, developers need to get on board

As we have said previously on Arm Blueprint, developers need to start building 64-bit versions of their applications and submit them to app stores now. In the future, app development on purely 64-bit mobile devices will bring further benefits, including reduced device complexity, lower development and testing costs, an improved time-to-market, and a stronger, healthier, and more robust and focused ecosystem.

In many cases, developers improve performance with their code by simply recompiling and targeting 64-bit.  For example, we are seeing an overall performance uplift for 64-bit vs. 32-bit on Arm Cortex A76 CPU-based devices of about 15 percent on the commonly used Android benchmark, GeekBench.

Other benchmarks such as LZBench Memcpy Compression/Decompression show a 91/80 percent uplift!  Additionally, through our partnership with Unity, we were able to run analysis across a range of content on the Unity 2018 game engine and saw an overall frame rate uplift ranging from 9.5 to 16.7 percent on 64-bit applications.

Supporting the ecosystem in transition to 64-bit

The move to 64-bit on mobile represents a ‘win-win’ for the entire ecosystem, providing performance and security benefits. Arm is fully prepared to commit to all our Cortex-A CPU mobile cores, both “big” and ”LITTLE”, being 64-bit only from 2023.

Arm is supporting the global Android ecosystem to ensure that everyone is ready to make the transition to 64-bit. We have technical resources, such as a whitepaper, developer materials, and links to technical articles to support developers making their apps compatible with 64-bit mobile devices.

 The 64-bit transition for most developers should be relatively pain-free, but developers should also be aware that Google has some great 64-bit coding and best practices material available if they have any questions or issues.

More on Mobile Computing solutions

Discover more information about the Total Compute solutions launch and the latest Armv9 big and LITTLE CPUs


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