UC San Diego researchers are working with Google to build a private cloud from 2,000 retired Pixel Fold motherboards, demonstrating how discarded smartphones could provide useful, low-cost computing capacity. "The full smartphone cluster is expected to launch this fall," reports The Register. "Depending on how well the initial phase goes, we're told the cluster could grow even larger." From the report Once the phone's motherboards have been extracted from their shells, the researchers say that the chips hiding within remain more than potent enough to be useful for a variety of tasks. In many cases, the single-threaded performance of these chips is as good as, if not better than, what you'd find from a many-cored datacenter chip. The Pixel Fold smartphones, which will form the basis of the cluster, are powered by a Google Tensor G2 processor with two 2.85 GHz Cortex-X1, two 2.35 GHz Cortex-A78 and four 1.80 GHz Cortex-A55 Arm cores, a Mali-G710 MP7 GPU, and 12 GB of system memory. Early benchmarking using the SPEC suite suggests that 25-50 phones should deliver performance similar to that of a conventional server.

The major challenge, instead, is distributing workloads across multiple devices, each of which has a handful of cores of one or more varieties, and most have 8-12 GB of memory. UCSD researchers are approaching this challenge from a couple of different angles. The first is by targeting applications that can easily fit within a single device. The second is using Kubernetes to orchestrate container deployments across clusters of 25-50 phones. For this to work, the devices first need to be flashed with a Linux operating system suitable for the job. While Android makes for a great handheld experience, it is not intended for server duty. In the blog post, researchers note that Android includes functionality intended to stop rogue applications from chewing up excessive amounts of memory and draining your battery. In server context, these safety mechanisms are no longer necessary.

[Ryan Kastner, an associate professor of computer science at UCSD] told us this was by no means an easy task, but the team has made steady progress toward getting Linux running smoothly on these devices, including support for the phone's onboard GPUs. Access to some functionality, like the chip's integrated tensor processing unit, remains elusive. Clustering these devices will require networking the phones together. Normally these devices would connect over cellular or Wi-Fi, but at this scale, this not only isn't practical, but also has implications for security, he explained. Instead, the team will employ PCBs that both supply power and break out wired Ethernet networking.

The researchers suggest that many EdTech, grading, and research workloads commonly run by universities in the cloud are small enough to run on the cluster without issue. "The vast majority of these applications are within the capabilities of a single smartphone to host, with the standard grading backend running on small cloud instances," a blog post detailing the planned deployment reads. "Early experiments show that even a moderately-sized cluster of 20 phones is capable of supporting peak submission rates for a 75+ student class."

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