Microsoft claims its latest Arm-powered Azure virtual machines can provide up to 50 percent better price-performance than similar instances using x86 processors. The keywords here are “up to” as it matters whether or not you’re relying on hyperthreading on the x86 systems.
The computing giant announced Monday that it is now previewing new D- and E-series VMs that use the Arm-compatible Altra server processors from chip startup Ampere Computing. The new Dpsv5 series is built for a variety of Linux enterprise application types, from web servers and .NET applications to open-source databases and application servers, while the new Epsv5 series is meant for memory-intensive Linux workloads, which includes data analytics, in-memory caching applications and gaming.
Evan Burness, principal program manager for Microsoft’s Azure HPC business, offered some important context to the 50 percent price-performance claim on Twitter. He said the Altra Arm-based VMs are capable of providing such an uplift when compared to similar x86 instances that have hyperthreading, or simultaneous multi-threading, turned on and in use. When hyperthreading is enabled on the x86 VMs, each physical processor core is represented by two virtual cores.
These hardware threads to software appear to be bonafide individual CPU cores, but in actual fact, each pair of hardware threads shares the same CPU core. Typically, each hardware thread in a physical core is doing work that doesn’t contend too much with its sibling hardware thread, or not at all, but sometimes, depending on the workload, they do contend for resources within the processor and that introduces some degree of slowdown. The Altra Arm Neoverse-based CPU cores are single-threaded. Thus with the Arm CPU cores, you have one core, one hardware thread; and with x86, you have one core, two hardware threads that vary a little with workload.
Burness said disabling hyperthreading so that when you spin up, say, a virtual machine with 16 x86 cores, you really are getting 16 physical CPU cores, and the gap between this x86 VM and its Altra VM equivalent is closed.
“Customers can close or eliminate gap just by disabling [hyperthreading] on the x86 D/E series,” he said.
Neither Burness or Microsoft’s blog post about the new Arm instances said whether the comparable x86 instances were based on Intel or AMD CPUs, both of which support hyperthreading, unlike Ampere’s that, as we said, support one hardware thread per CPU core.
The new Dpsv5 and Epsv5 VMs feature up to 64 virtual CPUs, and each vCPU can support memory configurations of 2GB, 4GB and 8GB for a total of 208GB for the entire instance. They also support up to 40 Gbps for networking, and there’s an option for high-performance local SSD storage.
The VMs support a range of operating systems, including Canonical Ubuntu Linux, CentOS and Windows 11 Professional and Enterprise Edition on Arm. Microsoft also plans future support for Red Hat Enterprise Linux, SUSE Linux Enterprise Server, Debian, AlmaLinux, and Flatcar.
The VMs have container support, too, via Azure Kubernetes Service.
For developers, Microsoft said the .NET5 and .NET6 platforms support Arm architecture. It’s also supported by Microsoft Visual C++ tools, the Visual Studio Code editor and Java through Microsoft’s recent JEP 388 contribution to OpenJDK.
Executives at Ampere and Arm said this is evidence that their CPU cores are ready for cloud primetime.
“The new Microsoft Azure VMs, powered by the Arm Neoverse-based Ampere Altra platform, highlight our deep collaboration with industry change-makers, and deliver on the power of choice to the cloud computing market,” said Chris Bergey, senior vice president and general manager of Arm’s infrastructure line of business.
As for whether anyone’s using the new Arm-based Azure instances, Microsoft offered as an example one company, Amadeus, which provides IT services for the travel industry.
“With Azure Arm64 VMs, we will be able to deliver higher throughput and even better experiences than the x86 VM that we’ve used in the past,” said Denis Lacroix, senior vice president of Amadeus’ cloud transformation program in a canned statement. “Azure Arm64 VM series have proven to be a reliable platform for our applications, and we’ve accelerated our plans to deploy Arm64-based Azure solutions.”
Executives at Linux shops Canonical, Red Hat and SUSE seem enthused too, but for the sake of brevity we’ll only pull from one of the quotes Microsoft provided.
“We see companies using Arm based architectures as a way of reducing both cost and energy consumption,” said Alexander Gallagher, vice president of public cloud at Canonical.
This push for more Arm-based cloud instances is expected to grow the CPU architecture’s penetration rate in datacenter servers to 22 percent by 2025, according to a recent report by research firm TrendForce, which pointed to Amazon Web Services’ homegrown CPUs as the major catalyst. ®