风险驱动的安全关键实时任务调度

 安全关键系统面临着日趋严峻的安全威胁，如何降低安全关键实时应用的风险成为挑战。通过结合风险评估与实时调度，给出一种风险驱动的任务调度方案。在分析非周期实时任务可调度性的基础上，提出一种基于处理器瞬态利用率、系统安全风险最小的在线调度近似算法。在不违背关键任务的时间约束和安全约束的前提下，该算法能够在低时间复杂度内得到安全性能确保的次优解。实验结果显示所提算法能明显降低安全关键实时应用的风险。具体来讲，最大安全风险可降低22.2%，并且在安全风险近似率上界为110%情况下，真实近似率最小为102.4%。

Risk-driven Scheduling Mechanism for Security-critical Real Time Tasks

Security-critical systems tend to be subjected to much more serious security threats, therefore it poses a great challenge to reduce the risk of security-critical applications. This article proposes a risk-driven task scheduling mechanism by incorporating risk assessment with real time scheduling. Based on the concept of synthetic utilization of aperiodic tasks, an online task scheduling algorithm is designed to schedule security-sensitive aperiodic tasks with minimal security risk. This algorithm is an approximate algorithm, which can yield security performance guaranteed near-optimal solution in low time complexity without violating the security-critical and time-critical constraints of tasks. Simulation results show that the proposed algorithm can signifi-cantly reduce the risk of security-critical real time applications and satisfy the bound of risk approximation ratio. Specifically, maximal security risk reduction of up to 22.2% is achieved, and minimal approximation ratio of security risk can decrease to 102.4% for the bound of 110%.