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Wang Yi - IEEE Xplore Author Profile

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Mixed-criticality (MC) systems have become indispensable in managing diverse tasks within unified computational environments, particularly in complex embedded systems like automotive and avionics industries. While traditional models adopt a pessimistic stance, discarding low-criticality tasks abruptly during high-criticality transitions, alternative strategies propose more gradual adjustments to m...Show More
Robot operating system (ROS) is a widely used robotic software development framework. In safety-critical applications that require timing guarantees, the first generation of ROS falls short. The introduction of ROS 2 has addressed some of these limitations, but its multithreaded executor still struggles to meet real-time requirements. To address this issue, we design a new multithreaded executor c...Show More
Many real-time systems process and react to external events by a chain of tasks, and have constraints on the maximum reaction time which describes how long it takes to respond to an external event. While a processing chain typically starts with a sampling task periodically triggered to sample the sensor data, other tasks in the chain could be triggered in two different ways: event-triggered or tim...Show More
ROS (Robot Operating System) is one of the most popular robotic software development frameworks. Robotic systems in safety-critical domains are usually subject to hard realtime constraints, so timing behaviors must be formally modeled and analyzed to guarantee that real-time constraints are always honored at run-time. Although a series of analysis techniques has been proposed to analyze the timing...Show More
Firmware update is an essential service on Internet-of-Things (IoT) devices to fix vulnerabilities and add new functionalities. Firmware update is energy-consuming since it involves intensive flash erase/write operations. Nowadays, IoT devices are increasingly powered by energy harvesting. As the energy output of the harvesters on IoT devices is typically tiny and unstable, a firmware update will ...Show More
In automotive systems, an important timing requirement is that the time disparity (the maximum difference among the timestamps of all raw data produced by sensors that an output originates from) must be bounded in a certain range, so that information from different sensors can be correctly synchronized and fused. In this paper, we study the problem of analyzing the worst-case time disparity in cau...Show More
A cause-effect chain is a sequence of multi-rate real-time tasks with data dependency. Cause-effect chains are generally subject to end-to-end timing constraints, especially in safety-critical systems. Communication paradigms greatly affect the end-to-end latency of cause-effect chains. This paper compares different communication paradigms (implicit communication, LET, DBP) with regards to the end...Show More
In mobile speech communication, the speech quality can be severely degraded when the mobile device users are in a noisy acoustic environment. To suppress environmental noises, deep learning based monaural speech separation methods have achieved remarkable progress on boosting the performance of the separation accuracy. However, the latency and computational cost of these methods remain far insuffi...Show More
The embedded system with energy harvest equipment collects the energy required for system operation from its working environment and releases it from the battery. However, the equipment can only provide intermittent power because environmental energy fluctuates. As a result, to assure the program’s progress, the program states must be stored timely and frequently. A promising paradigm for providin...Show More
Guaranteeing timing constraints for parallel real-time applications deployed on multicore platforms is challenging, especially for applications containing non-preemptive execution blocks, that suffer from priority inversions. In this article, we propose to model such applications using a sporadic directed acyclic graph (DAG) model where preemption may take place only between the nodes of a DAG tas...Show More
All existing work on real-time scheduling of parallel task graph models with shared resources assumes that a critical section must be contained inside a single vertex. However, this assumption does not hold in many realistic parallel real-time software. In this work, we conduct the first study on real-time scheduling and analysis of parallel task graphs where critical sections are allowed to cross...Show More
Many parallel real-time applications can be modeled as DAG tasks. Guaranteeing timing constraints of such applications executed on multicore systems is challenging, especially for the applications with non-preemptive execution blocks. The existing approach for timing analysis of such tasks with sporadic release relies on computing a bound on the interfering workload on a task, which depends on the...Show More
Deep neural networks (DNNs) have been widely used in many cyber–physical systems (CPSs). However, it is still a challenging work to deploy DNNs in real-time systems. In particular, the execution time of DNN inference must be predictable, s.t. it could be known whether the runtime inference can complete within a required timing constraint. Moreover, the timing constraints may change dynamically wit...Show More
Designing timing-anomaly free multiprocessor scheduling algorithms is a notoriously hard problem, especially for parallel tasks with non-preemptive execution regions. In this paper, we first propose a simple yet expressive model which abstracts a parallel task as a single computation unit, and then, present a sufficient condition for timing-anomaly free scheduling of such units. On top of this, we...Show More
The Round Robin scheduling policy is used in many real-time embedded systems because of its simplicity and low overhead. In this paper, we study a variation of Round Robin used in practical systems, named Lazy Round Robin, which is simpler to implement and has lower runtime overhead than ordinary Round Robin. The key difference between Round Robin and Lazy Round Robin lies in when the scheduler re...Show More
OpenMP is a popular programming framework in both general and high-performance computing and has recently drawn much interest in embedded and real-time computing. Although the execution semantics of OpenMP are similar to the DAG task model, the constraints posed by the OpenMP specification make them significantly more challenging to analyze. A tied task is an important feature in OpenMP that must ...Show More
In automotive industry, the production line for assembling mechanical parts of vehicles must place and weld hundreds of components on the right positions of the platform. The accuracy of deploying the components has great impact on the quality and performance of the produced vehicle. To ensure the assembly accuracy, a critical task in the production process is the so-called dimension quality contr...Show More
Locking protocol is an essential component in resource management of real-time systems, which coordinates mutually exclusive accesses to shared resources from different tasks. Although the design and analysis of locking protocols have been intensively studied for sequential real-time tasks, there has been a little work on this topic for parallel real-time tasks. In this article, we study the analy...Show More
Locking protocol is an essential component in resource management of real-time systems, which coordinates mutually exclusive accesses to shared resources from different tasks. OpenMP is a promising framework for multi-core realtime embedded systems as well as provides spin locks to protect shared resources. In this paper, we propose a resource model for analyzing OpenMP programs with spin locks. B...Show More
ROS (Robot Operating System) is currently the most popular robotic software development framework. Robotic software in safe-critical domain are usually subject to hard real-time constraints, so designers must formally model and analyze their timing behaviors to guarantee that real-time constraints are always honored at runtime. This paper studies real-time scheduling and analysis of processing cha...Show More
Most current real-time parallel applications can be modeled as a directed acyclic graph (DAG) task. Existing worst-case response time (WCRT) bounds (e.g., Graham's bound) derived for DAGs may be very pessimistic. No one precisely knows the gap between the WCRT bound and the actual WCRT. In this paper, we aim to derive the exact WCRT of a DAG task under the list scheduling upon multi-core platforms...Show More
Recent work has shown that the timing behavior of a real-time system can be utilized by attackers for various adverse purposes via schedule-based timing side-channel attacks. An important assumption in this type of attacks is the prior knowledge of attackers about the task parameter information, including the number of tasks in the system and the period and execution time of each task. The attacke...Show More
The hardness of analyzing conditional directed acyclic graph (DAG) tasks remains unknown so far. For example, previous researches asserted that the conditional DAG's volume can be solved in polynomial time. However, these researches all assume well-nested structures that are recursively composed by single-source-single-sink parallel and conditional components. For conditional DAGs in general that ...Show More
OpenMP is a promising framework to develop parallel real-time software on multi-cores. Although similar to the DAG task model, OpenMP task systems are significantly more difficult to analyze due to constraints posed by OpenMP specifications. One of the most interesting features in OpenMP is the support for nested parallelism, enjoying benefits in enhancing performance transparency of parallel libr...Show More
Capacity augmentation bound (CAB) is a widely used quantitative metric in theoretical analysis for directed acyclic graph (DAG) parallel real-time tasks, which reveals the key factors the schedulability of DAG tasks heavily depending on: the normalized utilization (the ratio of the total utilization to the core numbers) and the tensity (the maximum ratio of task's longest path length to task's dea...Show More