Raspberry Pi 3 Model B+ is the newest offering from the Raspberry Pi Foundation sharing much of the same features as the Raspberry Pi 3 Model B with small but significant improvements on many fronts while maintaining the same price. Below is some highlights.
- Increased CPU clock speed from 1.2GHz to 1.4GHz
- Increased memory throughput
- Integrated Heat Spreader (IHS) for SoC
- Integrated MxL7704 PMIC for power management and delivery
- Modularized WiFi/BT Radio with 5GHz and improved performance
- Gigabit Ethernet (albeit still over USB 2.0)
- Ethernet headers for PoE addon
We ran a comprehensive set of benchmarks on the new model, old model, and our boards to compare performance and power consumption.
We begin with heavily optimized C applications like C-Ray and SciMark2. Raspberry Pi 3 Model B+ is still utilizing 32-bit kernel and userland like its predecessor. Raspbian, the official OS of Raspberry Pi, has not moved to 64-bit ARMv8 despite the ARM Cortex-A53 CPU cores supporting it. Legacy 32-bit can help performance for this specific benchmark since some data structures and pointers are smaller than in 64-bit ARMv8 mode. Performance increases around 20% from the Model B, which means that the Raspberry Pi 3 Model B+ matches the performance of similarly clocked ROC-RK3328-CC. It is still slightly behind the AML-S905X-CC since that is about 100MHz faster.
Now we move onto server based workloads. Redis is a good test of overall system performance as it stresses not just the CPU but also the interrupt and memory subsystems. We see the Raspberry Pi 3 Model B+ improving greatly in performance over the previous Model B but still not enough to catch up with modern 28nm SoCs with faster DDR3/4 running ARMv8 kernel and userland.
Java benefits heavily from having native 64-bit arithmetic and performs signficantly faster on the boards running true 64-bit OSes. Despite nearly a 30% increase in performance, the Raspberry Pi 3 Model B+ is left behind.
Sysbench results should be taken with a grain of salt when comparing different binaries but this demonstrates the necessity of true 64-bit ARMv8 kernel and userland. Even with the performance gains, Raspberry Pi products are still held back by 32-bit ARMv7 Raspbian OS. Both the Renegade and Le Potato boards deliver more than 10x the performance.
Raspberry Pi 3 Model B+ uses a newly revised BCM2837B0. There are four limiting features of this SoC just like the previous BCM2837 in the Model B. First, it is missing ARM ISA’s Crypto Extensions. For encryption and decryption workloads such as VPN, SSL, SSH, and HTTPS, it’s NEON accelerated implementation is roughly 15x slower. This is one of the critical missing features that make the Raspberry Pi 3 Model B+ a poor choice for server based workloads that depend on these security instructions.
The second limiting feature has to do with the GPU which is a 30-bit design limited to 512MB of RAM. It only supports DDR2 so we haven’t seen the Raspberry Pi move to faster memory like LP/DDR3 like on Le Potato or LP/DDR4 on Renegade. As a result, memory intensive workloads will be much slower although the Model B+ is marginally faster than the Model B.