Google Develops In-House Arm 'Axion' CPU for Datacenters

Google was among the first hyperscalers build custom silicon for its services, starting first with tensor processing units (TPUs) for its AI initiatives, and then video transcoding units (VCUs) for the YouTube service. But unlike its industry peers, the company has been slower to adopt custom CPU designs, prefering to stick to off-the-shelf chips from the major CPUs. This is finally changing at Google, with the announcement that the company has developed its own in-house datacenter CPU, the Axion.

Google's Axion processor is based on the Arm Neoverse V2 (Arm v9) platform, which is Arm's current-generation design for high-performance server CPUs, and is already employed in other chips such as NVIDIA's Grace and Amazon's Graviton4. Within Google, Axion is aimed at a wide variety of workloads, including web and app servers, data analytics, microservices, and AI training. Google claims that the Axion processors boast up to 50% higher performance and up to 60% better energy efficiency compared to current-generation x86-based processors, as well as offer a 30% higher performance compared to competing Arm-based CPUs for datacenters. Though as is increasingly common for the cryptic cloud side of Google's business, least for now the company isn't specifying what processors they're comparing Axion to in these metrics.

While Google is not disclosing core counts or the full specifications of its Axion CPUs, the company is revealing that they are incorporating their own secret sauce into the silicon in the form of the company's Titanium purpose-built microcontrollers. These microcontrollers are designed to handle basic operations like networking and security, as well as offload storage I/O processing to Hyperdisk block storage service. As a result of this offloading, virtually all of the CPU core resources should be available to actual workloads. As for the chip's memory subsystem, Axion uses conventional dual-rank DDR5 memory modules.

"Google's announcement of the new Axion CPU marks a significant milestone in delivering custom silicon that is optimized for Google's infrastructure, and built on our high-performance Arm Neoverse V2 platform," said Rene Haas, CEO of Arm. "Decades of ecosystem investment, combined with Google's ongoing innovation and open-source software contributions ensure the best experience for the workloads that matter most to customers running on Arm everywhere." 

Google has previously deployed Arm-based processors for its own services, including BigTable, Spanner, BigQuery, and YouTube Ads and is ready to offer instances based on its Armv9-based Axion CPUs to its customers that can use software developed for Arm architectures.

Sources: Google, Wall Street Journal