[The Exiled]

ARM is the new RISC/Unix, RISC-V is the new ARM

When computer architectures change in the datacenter, the attack always comes from the bottom. And after more than a decade of sustained struggle, Arm Ltd and its platoons of licensees have finally stormed the glass house – well, more of a data warehouse (literally) than a cathedral with windows to show off technological prowess as early mainframe datacenters were – and are firmly encamped on the no longer tiled, but concrete, floors. The success of the proprietary minicomputers spawned a new breed of server makers, using computationally efficient RISC processors and operating systems that hewed to the Unix standard to various degrees that started off in scientific workstations in the mid-1980s. Intel expanded and hardened the X86 architecture, which was not initially as capacious or reliable as the RISC chips made by Sun, HP, Data General, ARM, and others. It didn’t need to be as computing on the Web was more distributed. What the Web-scale world needed was for datacenter compute to be was cheaper, and the X86 architecture was certainly cheaper than the RISC/Unix machines of the time. The relative affordability and absolute compatibility of the X86 architecture literally transformed the world.

And now the Arm CPU architecture that is in our tablets and smartphones and that took over as the embedded controller of choice from PowerPC, which displaced the Motorola 68K – and all four CPU architectures famously used in Apple machines – is pulling the X86 off that peak even as server volumes and revenues keep growing. If you ever wonder why Intel chief executive officer Pat Gelsinger is so hot to trot with opening up the Intel foundry business, this is why. Because, as we have been saying for more than a decade now, when Arm comes into the datacenter, another profit pool is going to be eliminated and the money is just going to end up in someone else’s pocket. Arm will very quickly become the CPU of choice on the clouds and among the hyperscalers unless Intel radically cuts prices on Xeon SP CPUs. With a 30 percent to 40 percent price/performance advantage for equivalent performance for a cloud instance, why would you deploy on an X86 instance instead of an Arm instance? Perhaps you buy a Xeon SP – and a back generation one at that – because AMD is sold out of Epyc CPUs and that is all you can get? Our point is that this is not just about mobile affecting servers.

John Cocke created a Reduced Instruction Set Computing architecture to try to make CPUs more efficient in the experimental 801 system in the 1970s, which ended up being used in IBM mainframe controllers and not much else. And along with the help of luminaries like David Patterson, Complex Instruction Set Computing (it wasn’t called until RISC made a distinction necessary) that prevailed in all CPU designs was replaced by the RISC method. Even the venerable X86 is a RISC computer at heart that is pretending to be a CISC machine, and has been for decades. We would not be surprised if IBM is, under the covers, doing the same thing with its System z mainframe motors.

The scale of Arm server deployments is on the order of hundreds of thousands of units against a few million units per quarter, but the Arm slice is growing fast. And the success of Arm is not being driven by performance per watt in the strictest sense, as was the drive early on with Arm server designs from a decade ago. This time, it is about an Arm CPU having equivalent or better performance than an X86 CPU, and much lower cost – and about the hyperscalers, cloud builders, and telcos having the option of customizing an Arm CPU design and having their own relationships with the few remaining advanced process chip foundries. This is all about IT organizations controlling their own fate.

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