Achieving Performance Balance for Dual-Criticality System Based on ARM TrustZone

Many mixed-criticality systems are composed of a RTOS (Real-Time Operating System) and a GPOS (General Purpose Operating System), and we define this as a mixed-timesensitive system. Complexity, isolation, real-time latency, and overhead are the main metrics to design such a mixed-timesensitive system. These metrics may conflict with each other, so it is difficult for them to be consistently optimized. Most existing implementations only optimize with part of the above metrics but not all. As the first contribution, this paper provides a detailed analysis of performance influencing factors which are exerted by various runtime mechanisms of existing mixed-time-sensitive systems. We figure out the difference in performance across system designs such as task switching, memory management, interrupt handling, and resource isolation. We propose the philosophy of utilizing TrustZone characteristics to optimize various mechanisms in mixed-time-sensitive systems. The second contribution of the paper is to propose a Trustzonebased solution - termed TZDKS - for mixed-time sensitive system. Appropriate utilization of TrustZone extensions helps TZDKS to implements (i) virtualization environment for GPOS and RTOS, (ii) high efficiency task switching, memory accessing, interrupt handling and device accessing which are verified by experiments. Therefore, TZDKS can achieve a full-scale balance amongst aforementioned metrics.