March 12, 2021

The Role of Open Source in Energy

This is my third blog post for the UVA class LPPS 4720.

The purpose of this assignment probably was to discuss how the Open Source movement will impact renewable energy, but I’m going to take this in a different direction and talk about computer chips. RISC-V is the first completely free and open CPU instruction set architecture (ISA) primarily for low-energy computers. According to its website, “the RISC-V ISA delivers a new level of free, extensible software and hardware freedom on architecture, paving the way for the next 50 years of computing design and innovation”.

The “brain” of a computer is a little piece of silicon called the Central Processing Unit, or CPU. This is what makes computers so powerful—you can do almost anything with a CPU. Historically, CPUs have been extremely expensive to design and manufacture due to their inherent complexity. In fact, the first Silicon Valley startup pioneered this industry and laid the foundation for the region’s technological dominance. Because of the high costs associated with the CPU industry, companies typically use patents and other forms of IP to protect their ISAs, the primary descriptions for how their CPUs are modeled. The vast majority of personal computers today use high-powered x86-64 Intel or AMD CPUs and most smartphones use low-powered ARM CPUs, both of which are proprietary. This is a problem for some applications because there is little transparency into how these chips actually work at a low-level, leading to closed ecosystems where only a few key players can innovate to create better processor designs.

Computers are pervasive in modern society, and while ARM processors are already incredibly efficient compared to equivalent x86-64 processors, an open source ISA can lead to more competition, driving companies to produce more energy-efficient CPUs. According to the United States Energy Information Administration, “computers and office equipment account for largest share of commercial sector electricity consumption” and this figure will likely continue to grow in the future. With the increasing popularity of IoT, the demand for low-power CPUs that can power all these new “smart” devices is rising. ARM, like RISC-V, is just an ISA, but the company is able to license this ISA to CPU manufacturers for a steep price, which is one of the reasons why many mobile CPUs are so expensive. Manufacturers who use RISC-V would not have to pay to license the technology because it is completely free and open source. This would in turn lower the cost of efficient low-power CPUs and help offset some of the massive energy usage of modern computing infrastructure.

Another benefit of an open source ISA is that CPU manufacturers can create custom chips that are extremely efficient at performing a specific task, in contrast to normal CPUs which are decent at performing a wide variety of tasks. This is important because according to Jim Hogan, “next generation SoCs will rely heavily on customized processors to implement domain-specific architectures (DSAs) to achieve the performance and power improvements that Moore’s law can no longer provide”. Better yet, “the heavy lifting of developing the ISA, toolchain and software stack no longer falls on a single company”, so the RISC-V community can work together in the true spirit of open source to build the next generation of microchip hardware. For example, it’s nearly impossible right now to build an IoT device capable of training sophisticated machine learning models for a reasonable price due to how much energy and computing power this requires; however, with a custom chip designed with hardware specifically optimized for machine learning, this may soon become a reality. Imagine something like a Google Home Mini that has best-in-class speech recognition without having to send massive amounts of data back to Google’s servers for processing—instead, everything can be localized to the device itself. Such a device would be a boon to both privacy and the energy grid since servers draw massive amounts of power.

While RISC-V CPUs may never fully replace ARM chips, they can fill an increasingly viable niche for low-power efficient custom SoCs that power the next generation of IoT devices. The open source community around RISC-V is steadily growing which will likely lead to revolutionary designs for the next generation of embedded systems that can strive to minimize energy consumption.

© Samarth Kishor 2020

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