Risky Business

As I do at least twice every year, I changed my plans for this column at the very last minute. This time, some interesting hardware came into the lab rightfully deserving of analysis – a new single-board-computer (SBC) that is part of the first production run of the BeagleV-Ahead [1], the latest addition to the BeagleBone family [2] (Figure 1). This new entry is built around a CPU based on the up-and-coming RISC-V architecture [3] (Figure 2). RISC-V is a relatively recent open source CPU instruction set available royalty-free and has successfully drawn interest from more than a dozen chip suppliers so far. It cannot yet compete with x86 chips from Intel and AMD, or even the best many-core ARM offerings, but it shows great promise and is therefore worth tinkering with.

Figure 1: The BeagleV-Ahead board, seen installed in a Seeed Studio re_computer standard SBC case.

Figure 2: BeagleV-Ahead, bottom view.

What's in the Box?

Despite its different architecture, the BeagleV-Ahead is designed around the well-known BeagleBone Black form factor. Featuring a quad-core Xuantie C910 processor designed by Alibaba's team and later released as open source [4], this out-of-order, pipelined core is the fastest RISC-V CPU made available commercially to date. A modern 64-bit CPU, the chip is a product of T-Head, Alibaba's semiconductor unit, and it is apparently commercially restricted by the federal government, because I had to confirm that my order was not intended for export.

Modern politics aside, the CPU itself has some interesting extensions for artificial intelligence (TPU delivering 4 TOPS INT8 at 1GHz), includes a 50 GFLOPS GPU, and is accompanied by 4GB of RAM and 16GB of embedded multimedia card (eMMC) flash storage. Interfaces include USB3, micro-HDMI, microSD card, display serial interface (DSI), and camera serial interface (CSI) alongside the standard Beagle "cape" GPIO connectors. Connectivity options include gigahertz wired Ethernet and WiFi. The eMMC can be flashed to a different distribution over USB, and serial debugging interfaces are accessible. Power is supplied over a 2.1mm barrel connector at 5V, or directly over USB. See Figure 3 for a layout diagram and Table 1 for the full specifications.

Figure 3: The BeagleV-Ahead port and chip layout. © beagleboard.org

Once a piece of new hardware works, the immediate next challenge is the completeness and maintainability of the binary support package. I cannot speak to the latter as it pertains to the future, but the availability of a Yocto distribution (2023-06 preloaded in flash) [5] suggests one could self-support the board with custom builds easily enough once it is no longer the focus of the vendor's attention. For the former, the available port of Ubuntu (2023-07 based on Lunar Lobster) [6] makes the case nicely. It is worth noting that the Yocto image has no valid HDMI configuration, and switching to a text terminal (Ctrl+Alt+F1) is necessary.

To the Moon!

The Yocto image in built-in flash is a convenient, albeit sparse, development environment. For benchmarks, Ubuntu is the obvious choice between the two options. Flashing the much larger Ubuntu base image is a relatively painless process that I will not detail, for the sake of brevity (Figure 4). After flashing Ubuntu 23.04 "Lunar" to the on-board eMMC I have convenient online access to the full Main and Universe repositories to further my system exploration. With access to Ubuntu's RISC-V Universe repository, you can just install 7-Zip [7], as discussed in a previous article [8]:

$ sudo apt install p7zip-full

Figure 4: The Ubuntu image sets up a convenient (but slow) Xfce environment.

As I explained then, comparing systems should always involve a real workload, and comparing RISC-V with ARM on the grounds of how fast it can compress data feels more truthful than doing so on pure disjoint CPU operations. The benchmark has many switches, of course, but a first pass can be executed with just

$ 7z b

Listing 1 shows the RISC-V speeds posted by the SBC. The previous article [8] included results for a single-core virtualized Xeon core and an Apple M1 ARM Desktop, the latter extracted from the exceptional online library of CPU benchmarks that 7-Zip hosts [9]. A more apt comparison is found in Listing 2, with the results posted by a Raspberry Pi 400 [10], which is essentially a Raspberry Pi 4 (Broadcom BCM2711 Cortex-A72, ARM v8 quad-core running at 1.8GHz). The ARM chip in the Pi is posting 6.2 billion instructions per second compared with 4.5 for the RISC-V in the Beagle.

7-Zip 16.02 : Copyright (c) 1999-2016 Igor Pavlov : 2016-05-21
p7zip Version 16.02 (locale=C.UTF-8,Utf16=on,HugeFiles=on,64 bits,4 CPUs LE)
LE
CPU Freq: 64000000 64000000 - - - - - - -
RAM size:    2923 MB,  # CPU hardware threads:   4
RAM usage:    882 MB,  # Benchmark threads:      4
                       Compressing  |                  Decompressing
Dict     Speed Usage    R/U Rating  |      Speed Usage    R/U Rating
         KiB/s     %   MIPS   MIPS  |      KiB/s     %   MIPS   MIPS
22:       3252   300   1054   3164  |      73071   398   1566   6234
23:       3170   314   1029   3230  |      68302   399   1482   5910
24:       3086   320   1037   3318  |      66423   399   1463   5831
25:       2904   327   1014   3316  |      62838   397   1407   5593
----------------------------------  | ------------------------------
Avr:             315   1033   3257  |              398   1480   5892
Tot:             357   1256   4575

7-Zip [32] 16.02 : Copyright (c) 1999-2016 Igor Pavlov : 2016-05-21
p7zip Version 16.02 (locale=en_US.UTF-8,Utf16=on,HugeFiles=on,32 bits,4 CPUs LE)
LE
CPU Freq:   975  1181  1798  1798  1796  1798  1798  1798  1798
RAM size:    3838 MB,  # CPU hardware threads:   4
RAM usage:    882 MB,  # Benchmark threads:      4
                       Compressing  |                  Decompressing
Dict     Speed Usage    R/U Rating  |      Speed Usage    R/U Rating
         KiB/s     %   MIPS   MIPS  |      KiB/s     %   MIPS   MIPS
22:       3787   361   1021   3685  |     109383   399   2341   9332
23:       3656   363   1025   3725  |     106167   399   2304   9186
24:       3214   337   1027   3456  |      97910   383   2243   8595
25:       3294   362   1040   3762  |      91207   375   2165   8117
----------------------------------  | ------------------------------
Avr:             356   1028   3657  |              389   2263   8808
Tot:             372   1646   6232