Modern UAV architectures increasingly aim to unify high-level autonomy and low-level flight control on a single General-Purpose Operating System (GPOS). However, complex multi-core System-on-Chips (SoCs) introduce significant timing indeterminism due to shared resource contention. This paper performs an architectural analysis of the PREEMPT RT Linux kernel on a Raspberry Pi 5, specifically isolating the impact of kernel activation paths (deferred execution SoftIRQs versus real-time direct activation) on a 250 Hz control loop. Results show that under heavy stress, the standard kernel is unsuitable, exhibiting worst-case latencies exceeding 9 ms. In contrast, PREEMPT RT reduced the worst-case latency by nearly 88 percent to under 225 microseconds, enforcing a direct wake-up path that mitigates OS noise. These findings demonstrate that while PREEMPT RT resolves scheduling variance, the residual jitter on modern SoCs is primarily driven by hardware memory contention.

翻译：现代无人机架构日益趋向于在单一通用操作系统（GPOS）上统一高层自主性与低层飞行控制。然而，复杂的多核片上系统（SoC）由于共享资源争用引入了显著的时间不确定性。本文对树莓派5上的PREEMPT_RT Linux内核进行了架构分析，特别隔离了内核激活路径（延迟执行的软中断与实时直接激活）对250 Hz控制回路的影响。结果表明，在重负载压力下，标准内核不适用，其最差情况延迟超过9毫秒。相比之下，PREEMPT_RT将最差情况延迟降低了近88%，降至225微秒以下，通过强制执行直接唤醒路径来抑制操作系统噪声。这些发现表明，尽管PREEMPT_RT解决了调度方差问题，但现代SoC上的残余抖动主要由硬件内存争用驱动。