Manually Inserted Instrumentation

From TracingWiki

Manually inserted instrumentation is present in most large systems for logging or tracing purposes. Libraries exist to provide simple, single line, instrumentation statements in most programming languages. For instance, the Linux kernel used printk statements from the very beginning, even though they are relatively low performance and not optimized for multi-processors or real-time.

Tracepoints are manually inserted at locations in the source code where significant events occur, which may help to understand the system behavior for performance tuning, monitoring or troubleshooting.