intermediate · latency
Five Seconds at 15% CPU
API p99 is 5 seconds. CPU is at 15%, memory is fine. What is going on?
Practical scenario
A reporting API has a p99 of 5.2 s. Every host graph is green: CPU 15%, memory 40%, network unremarkable. The database team says their metrics look normal too.
What it tests
- • Whether the candidate can distinguish waiting from working
- • Breadth of the "what could it be waiting for" list
- • Whether they know utilisation cannot detect waiting