Virtualization environments (e.g., containers and hypervisors) achieve isolation of multiple runtime entities but result in two mutually isolated guest and host layers. Such cross-ayer isolation could cause high latency and low throughput of the system. Previous aware scheduling and double scheduling fail to achieve bidirectional coordination between the guest and host layers. To address this challenge, we develop DCS3, a Dual-layer Co-aware Scheduler that combines stealing balance and synchronized priority. Stealing balancing migrates tasks between virtual CPU (vCPU) queues for load balance based on the workloads of physical CPUs (pCPUs). Synchronized priority dynamically adjusts the thread priorities running on the pCPUs according to the current vCPU workloads. The vCPUs and pC-PUs belong to the guest and host layers, respectively. Compared with aware scheduling, double scheduling, and DCS2 (i.e., DCS3 without synchronized priority), DCS3 has the following obvious advantages: 1) Requests Per Second (RPS) increases by up to 52%, 55%, and 2%, respectively; 2) request latency decreases by up to 72%, 71%, and 20%, respectively.

The microcomputer cluster is a group of connected microcomputers that work together to perform as a single system. Unlike high-performance computer clusters, microcomputer clusters are designed to provide reliable and efficient services for safety-critical embedded systems, which usually require low SWaP (Size, Weight, and Power) because of the high stability and cost control requirements. Considering that safety-critical systems have strict real-time constraints (i.e., deadline constraints) and resource constraints, each microcomputer usually needs to run a Real-Time Operating System (RTOS) instead of Linux to achieve precise scheduling and control, and a high-speed real-time network such as Time-Triggered Ethernet (TTE) is required for intra-cluster communication. In microcomputer clusters, a load imbalance between microcomputers usually leads to system instability, and a lightweight application distribution framework automatically migrates applications among microcomputers, thereby breaking resource isolation and improving resource utilization. However, mainstream application distribution frameworks, such as Kubernetes (K8s), MicroK8s, and K3s, can be applied neither to RTOS nor to TTE. In this study, we design a lightweight application distribution framework with automated and real-time computing and communication (ARC2). ARC2 monitors the microcomputer cluster resource state in real-time and introduces a resource hierarchical pooling method to utilize cluster resources flexibly. It employs TTE for application distribution combined with a real-time scheduling strategy, achieving low end-to-end latency and load balancing. It simplifies the existing application distribution framework and introduces a low-complexity cluster management logic to achieve low resource overhead. We conduct experimental evaluations on a heterogeneous platform. The results show that: (1) the load imbalance is reduced by at least 59.81% compared to the original system; (2) the deviation in real-time monitoring traffic is reduced by an average of 56.7 ms, with the application distribution success rate reaching 100% and an average distribution time of 393.0 ms; and (3) the CPU, memory, and bandwidth overhead are 9%, 3 MB, and 0.104 Mb/s, respectively.

5G mobile communication techniques are widely applied in ubiquitous communication scenarios (e.g., smart navigation and smart transportation), which require time synchronization among mobile devices. However, the built-in time synchronization software of Android phones presents large time offsets with hundreds of milliseconds (ms), and the mainstream time synchronization techniques have specific limitations: 1) the Network Time Protocol (NTP) has too large offset to meet the real-time information interaction among mobile devices; 2) the Linux Precision Time Protocol (LinuxPTP) exists hardware dependence and cannot be implemented on Android and 5G networks; and 3) the Global Navigation Satellite System (GNSS) requires installing a hardware receiver on each mobile device. In this study, we develop a Mobile Precision Time Protocol (MobiPTP), which is hardware-independent and compatible with various network types, including Wide-Area Network (WAN), Local-Area Network (LAN), wired and wireless networks. The main challenges include signal strength instability and uplink-downlink asymmetry. We propose a dynamic time synchronization algorithm and an asymmetry compensation strategy to overcome these challenges. Regardless of high-speed mobile or crowded conditions in 5G networks, MobiPTP demonstrates an average offset of 9 ms, outperforming the NTP-based open-source software Chrony (about 30 ms). MobiPTP has been successfully deployed in multiple real-world ubiquitous communication scenarios and always demonstrates much lower offsets than Chrony.