Profiling CPU, Allocation, Locks, and I/O
Different profilers answer different questions. CPU samples, allocation events, lock waits, scheduler traces, and I/O traces cannot be collapsed into one universal profile.
Planned model
Inject known CPU, allocation, contention, and I/O delays into a pipeline, then reveal what sampling, tracing, and instrumentation observe or miss.
Questions
- Is time spent running, runnable, sleeping, or waiting on a resource?
- What bias and overhead does the collection method introduce?
- Can symbols and timestamps be trusted?
Exercise
Choose evidence needed to distinguish a hot loop, lock convoy, page fault, and scheduler delay that produce the same wall-clock symptom.