OS-capable embedded systems exhibiting a very low power consumption are available at an extremely low price point. It makes them highly compelling in a datacenter context. We show that sharing long-running, compute-intensive datacenter workloads between a server machine and one or a few connected embedded boards of negligible cost and power consumption can yield significant performance and energy benefits. Our approach, named Heterogeneous EXecution Offloading (HEXO), selectively offloads Virtual Machines (VMs) from server-class machines to embedded boards. Our design tackles several challenges. We address the Instruction Set Architecture (ISA) difference between typical servers (x86) and embedded systems (ARM) through hypervisor and guest OS-level support for heterogeneous-ISA runtime VM migration. We cope with the low amount of resources in embedded systems by using lightweight VMs – unikernels – and by using the server's free RAM as remote memory for embedded boards through a transparent lightweight memory disaggregation mechanism for heterogeneous server-embedded clusters, called Netswap. VMs are offloaded based on an estimation of the slowdown expected from running on a given board. We build a prototype of HEXO and demonstrate significant increases in throughput (up to 67%) and energy efficiency (up to 56%) using benchmarks representative of compute-intensive long-running workloads.

Edge computing is a recent computing paradigm that brings cloud services closer to the client. Among other features, edge computing offers extremely low client/server latencies. To consistently provide such low latencies, services should run on edge nodes that are physically as close as possible to their clients. Thus, when the physical location of a client changes, a service should migrate between edge nodes to maintain proximity. Differently from cloud nodes, edge nodes integrate CPUs of different Instruction Set Architectures (ISAs), hence a program natively compiled for a given ISA cannot migrate to a server equipped with a CPU of a different ISA. This hinders migration to the closest node. We introduce H-Container, a system that migrates natively compiled containerized applications across compute nodes featuring CPUs of different ISAs. H-Container advances over existing heterogeneous-ISA migration systems by being (a) highly compatible – no user’s source-code nor compiler toolchain modifications are needed; (b) easily deployable – fully implemented in user space, thus without any OS or hypervisor dependency, and (c) largely Linux-compliant – it can migrate most Linux software, including server applications and dynamically linked binaries. H-Container targets Linux and its already-compiled executables, adopts LLVM, extends CRIU, and integrates with Docker. Experiments demonstrate that H-Container adds no overheads during program execution, while 10–100 ms are added during migration. Furthermore, we show the benefits of H-Container in real-world scenarios, demonstrating, for example, up to 94% increase in Redis throughput when client/server proximity is maintained through heterogeneous container migration.

Edge computing is a recent computing paradigm that brings cloud services closer to the client. Among other features, edge computing offers extremely low client/server latencies. To consistently provide such low latencies, services need to run on edge nodes that are physically as close as possible to their clients. Thus, when a client changes its physical location, a service should migrate between edge nodes to maintain proximity. Differently from cloud nodes, edge nodes are built with CPUs of different Instruction Set Architectures (ISAs), hence a server program natively compiled for one ISA cannot migrate to another. This hinders migration to the closest node.

OS-capable embedded systems exhibiting a very low power consumption are available at an extremely low price point. It makes them highly compelling in a datacenter context. In this paper we show that sharing long-running, compute-intensive datacenter HPC workloads between a server machine and one or a few connected embedded boards of negligible cost and power consumption can bring significant benefits in terms of consolidation. Our approach, named Heterogeneous EXecution Offloading (HEXO), selectively offloads Virtual Machines (VMs) from server class machines to embedded boards. Our design tackles several challenges. We address the Instruction Set Architecture (ISA) difference between typical servers (x86) and embedded systems (ARM) through hypervisor and guest OS-level support for heterogeneous-ISA runtime VM migration. We cope with the low amount of resources in embedded systems by using lightweight VMs: unikernels. VMs are offloaded based on an estimation of the slowdown expected from running on a given board. We build a prototype of HEXO and demonstrate significant increase in throughput (up to 67%) and energy efficiency (up to 56%) over a set of macro-benchmarks running datacenter compute-intensive jobs.

In this paper, we investigate the effectiveness of multiprocessor architectures with ISA-different cores for executing HPC workloads. Our envisioned design point in the heterogeneous architecture space is one with multiple cache-coherency domains, with each domain hosting cores of a different ISA and no coherency between domains. We prototype such an architecture using an Intel Xeon x86-64 server and a Cavium ThunderX ARMv8 server, interconnected using a high-speed network fabric. We design, implement, and evaluate policies for scheduling HPC applications with the goal of maximizing workload makespan. Our results reveal that such an architecture is most effective for workloads that exhibit diverse execution times on ISA-different CPUs, with gains exceeding 60% over ISA-homogeneous architectures. Furthermore, cross-ISA execution migration can yield gains up to 38%.