Micro-core architectures combine many low memory, low power computing cores together in a single package. These are attractive for use as accelerators but due to limited on-chip memory and multiple levels of memory hierarchy, the way in which programmers offload kernels needs to be carefully considered. In this paper we use Python as a vehicle for exploring the semantics and abstractions of higher level programming languages to support the offloading of computational kernels to these devices. By moving to a pass by reference model, along with leveraging memory kinds, we demonstrate the ability to easily and efficiently take advantage of multiple levels in the memory hierarchy, even ones that are not directly accessible to the micro-cores. Using a machine learning benchmark, we perform experiments on both Epiphany-III and MicroBlaze based micro-cores, demonstrating the ability to compute with data sets of arbitrarily large size. To provide context of our results, we explore the performance and power efficiency of these technologies, demonstrating that whilst these two micro-core technologies are competitive within their own embedded class of hardware, there is still a way to go to reach HPC class GPUs.

Micro-core architectures combine many simple, low memory, low power-consuming CPU cores onto a single chip. Potentially providing significant performance and low power consumption, this technology is not only of great interest in embedded, edge, and IoT uses, but also potentially as accelerators for data-center workloads. Due to the restricted nature of such CPUs, these architectures have traditionally been challenging to program, not least due to the very constrained amounts of memory (often around 32KB) and idiosyncrasies of the technology. However, more recently, dynamic languages such as Python have been ported to a number of micro-cores, but these are often delivered as interpreters which have an associated performance limitation.Targeting the four objectives of performance, unlimited code-size, portability between architectures, and maintaining the programmer productivity benefits of dynamic languages, the limited memory available means that classic techniques employed by dynamic language compilers, such as just-intime (JIT), are simply not feasible. In this paper we describe the construction of a compilation approach for dynamic languages on micro-core architectures which aims to meet these four objectives, and use Python as a vehicle for exploring the application of this in replacing the existing micro-core interpreter. Our experiments focus on the metrics of performance, architecture portability, minimum memory size, and programmer productivity, comparing our approach against that of writing native C code. The outcome of this work is the identification of a series of techniques that are not only suitable for compiling Python code, but also applicable to a wide variety of dynamic languages on micro-cores.

Micro-core architectures combine many simple, low memory, low power computing cores together in a single package. These can be used as a co-processor or standalone but due to limited on-chip memory and esoteric nature of the hardware, writing efficient parallel codes for these chips is challenging. In this paper we discuss our very low memory implementation of Python, ePython, supporting the rapid development of parallel Python codes for these co-processors. An offload abstraction is introduced, where programmers decorate specific functions in their Python code, running under any Python interpreter on the host CPU, with the underlying technology then taking care of the low level data movement, scheduling and ePython execution on the microcore co-processor. A benchmark solving Laplace's equation for diffusion via Jacobi iteration is used to explore the performance of ePython on three different micro-core architectures, and introduces work around native compilation for micro-cores and the performance advantages that this can provide.

Leveraging real-time data to detect disasters such as wildfires, extreme weather, earthquakes, tsunamis, human health emergencies, or global diseases is an important opportunity. However, much of this data is generated in the field and the volumes involved mean that it is impractical for transmission back to a central data-centre for processing. Instead, edge devices are required to generate insights from sensor data streaming in, but an important question given the severe performance and power constraints that these must operate under is that of the most suitable CPU architecture. One class of device that we believe has a significant role to play here is that of micro-cores, which combine many simple low-power cores in a single chip. However, there are many to choose from, and an important question is which is most suited to what situation. This paper presents the Eithne framework, designed to simplify benchmarking of micro-core architectures. Three benchmarks, LINPACK, DFT and FFT, have been implemented atop of this framework and we use these to explore the key characteristics and concerns of common micro-core designs within the context of operating on the edge for disaster detection. The result of this work is an extensible framework that the community can use help develop and test these devices in the future.