Does PREEMPT_RT guarantee a Linux application's response deadline?

PREEMPT_RT changes kernel behavior to improve preemptibility, but the application, drivers and hardware still affect timing. Identify the complete path from input event to output action, including interrupt handling, scheduling, computation and I/O completion.

Measure under representative worst-case load, including storage, networking and relevant device interrupts. Avoid allocation, page faults or blocking operations in the critical path where the design requires bounded execution. Priority assignments must account for shared resources and lower-priority work that the task depends on.

Report tail latency, deadline misses and test conditions rather than only an average. Scheduling benchmarks can reveal one part of the system, but the application needs its own end-to-end test. Use hardware timing or a dedicated controller where the required bound cannot be established on the selected Linux platform.