Embedded Linux or RTOS: which requirements decide?

Define the deadlines the system must meet

Replace the generic question of which system is better with observable requirements. Which tasks have deadlines? What happens when a deadline is missed? What is the acceptable delay between an input and its response? How long may the product take to start?

An RTOS provides mechanisms to organize tasks and priorities, but predictability depends on the complete implementation: interrupts, drivers, critical sections and workload. Selecting an operating system does not replace measurements on actual hardware.

Assess the application and its dependencies

Linux may suit a product that needs a broad software stack, isolated processes, network interfaces and complex applications. It also introduces responsibilities for the system image, updates, storage and package maintenance.

An RTOS may suit a focused control workload and a resource-constrained platform. Include the effort to integrate protocols, diagnose failures and maintain libraries over time in the decision.

Consider separating responsibilities

Some architectures use a microcontroller for control and a Linux processor for connectivity and applications. The interface between them must define states, timing, recovery from failure and compatibility across versions.

Before committing to a platform, run a proof of concept with critical tasks, expected communication load and error conditions. Record latency, memory use, startup and recovery behavior. Choose the architecture using that evidence.