Raspberry Pi 4 Model B Performance Benchmarks

Raspberry Pi Specification

• Broadcom BCM2711 SoC
• 1.5GHz Clock
• 4 x Arm Cortex-A72 cores, 64-bit armv8.0-a architecture
• 1 x 128 bit SIMD pipeline per core, capable of 2 floating point operations on 2 doubles per clock cycle using FMA instructions
• 4GB RAM

Baseline High Performance Linpack (HPL) Benchmarks

Software

HPL benchmarks Ubuntu 20.04 LTS 64-bit Pre-Installed Server default packages:

• OpenBLAS (serial) 0.3.8
• BLIS (serial) 0.6.1
• OpenMPI 4.0.3

HPL-2.3 built from source with -O3 -march=armv8-a -mtune=cortex-a72

Theoretical Maximum Performance

The theoretical maximum performance for a single node:

Rpeak = 1.5GHz clock * 4 cores * 4 floating point operations per clock cycle
Rpeak = 24 Gflops

Using 80% of memory results in a maximum achievable:

80% Rpeak = 19.2 Gflops per node
80% Rpeak =  4.8 Gflops per core

Benchmarks

Please note, these are not Problem Size vs Gflops benchmarks. I know in advance that I want to use a problem size which utilises 80% of available memory.

So, for each value of NB, N is selected to be an integer multiple of NB as close as possible to 80% of memory:

N = abs(0.8 * sqrt(4 * node_count x 1024^3) / NB) * NB

Gflops vs NB 1 Core 80% Memory

Gflops vs NB 1 Node (4 Cores) 80% Memory

Gflops vs NB 2 Nodes 80% Memory

Gflops vs Nodes 80% Memory

Rmax is the maximum observed Gflops using the following values of NB:

• OpenBLAS NB = 120
• BLIS NB = 168

These values achieved Rmax on the 2 node benchmark. The assumption that this extrapolates to the 8 node benchmark needs further investigation.