Feature: Software and tools


Seeing inside the scheduler: RTOS trace and observability matter!


By Andreas Lifvendahl, CEO, Percepio


M 38 March 2026 www.electronicsworld.co.uk


odern embedded systems increasingly rely on real-time operating systems (RTOS) to manage growing soſtware complexity. Multithreading, pre-emptive scheduling and inter-task communication enable efficient use of hardware resources, but they also


introduce subtle timing and concurrency problems that are difficult to reason about from source code alone. As embedded applications move toward greater connectivity, tighter


timing requirements and multi-core architectures, the need for better visibility into RTOS behaviour at runtime has become harder to ignore.


The hidden complexity of RTOS-based systems RTOS applications rarely fail because a single task behaves incorrectly in isolation. Instead, problems emerge from interactions: a task blocked on a mutex, an unexpected priority inversion, a higher-priority interrupt arriving at an inconvenient moment, or timing variations that only occur under specific system load. Tese interactions are oſten invisible at the code level. While the


source may show which tasks use which synchronisation objects, it does not show when these interactions occur, how long tasks are blocked, or how scheduling decisions play out over time. On multi-core systems, additional sources of non-determinism such as cache effects and shared buses further complicate the picture. As a result, systems can appear stable during testing, only to exhibit elusive failures in the field that are nearly impossible to reproduce.


Traditional debugging falls short Conventional embedded debugging tools were not designed to answer system-level timing questions. Breakpoints and single stepping fundamentally disturb the timing of a real-time system, making them


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