Minimally-Intrusive Data Monitoring for Real-Time Linux Applications

Real-time systems often require close inspection of what’s happening in memory, especially when trying to validate behavior under dynamic conditions. But conventional memory monitoring tools either disrupt system performance or require the application to be stopped entirely.

NightProbe was built to avoid those limitations. It’s a data monitoring tool that lets developers observe, record, and even modify program variables without interrupting application execution. Whether you’re debugging a simulation, injecting faults for testing, or building a prototype interface, NightProbe gives you access to the system’s internal state without affecting its timing or stability.

Monitoring Without Interference

At the core of NightProbe is a non-intrusive approach to monitoring. Instead of inserting hooks into the application or altering control flow, it maps the target’s memory space and samples data directly. This approach lets you observe the system in its natural operating state.

NightProbe can read from:

• Running programs
• Shared memory segments
• Static memory devices

It supports both synchronous (clocked) and asynchronous (on-demand) sampling, allowing you to configure how and when data is captured. If needed, it can also write values back into memory, enabling live data modification or targeted fault injection.

Flexible Data Views and Formats

NightProbe supports a wide range of data types, including scalar variables, arrays, and structures in C, C++, Ada, and Fortran. You can view this data in multiple formats, including:

• Tables
• Graphs
• Lists
• Spreadsheets

These views are interactive. If you want to change a value say, set a buffer length or simulate a sensor spike you can type the new value directly into the interface. The system will apply the change without restarting the application or recompiling code.

This is particularly useful during development, when you need to test edge cases or explore how your software handles unexpected conditions.

Integrated with NightTrace

NightProbe works alongside NightTrace, Concurrent Real-Time’s event tracing tool. You can log data points using tracepoints and analyze them in the context of system events, interrupts, or process scheduling.

This makes it easier to correlate application-level data with broader system behavior. For example:

• How did a PID controller variable shift during a spike in CPU usage?
• What was the buffer fill level at the time of a missed deadline?
• Did a memory value change just before a thread was blocked?

By combining variable data with system traces, NightProbe helps paint a fuller picture of what’s going wrong and when.

No Source Code Changes Required

One of NightProbe’s advantages is that it doesn’t require access to your application’s source code. As long as the binary contains symbol table and debug information, NightProbe can find variables and monitor them.

This allows you to work with legacy code, vendor binaries, or complex systems without needing to rebuild or recompile. Developers can search symbol tables or browse variables directly through the interface.

This is especially valuable in safety-critical environments where source access may be restricted or changes to production code are discouraged.

Use Cases: From Debugging to Production

NightProbe can be used throughout the software lifecycle:

• During development, it helps test algorithm behavior under different input conditions without altering the application.
• In debugging, it allows for real-time fault reproduction by adjusting values on the fly.
• In production, it can serve as a lightweight monitoring panel, visualizing key variables over time.

NightProbe also supports recording to disk, so you can log data for later playback and analysis. This is useful for post-mortem reviews or repeating test cases exactly as they happened.

Minimal System Overhead

NightProbe was designed for performance. Its memory mapping and sampling techniques minimize CPU overhead and avoid introducing latency. This makes it well-suited for real-time systems where every microsecond counts.

Because it operates independently from the application thread, there is no contention for resources or disruption of scheduling. You can confidently use NightProbe on live systems without risk to determinism.