perf: Linux profiling with performance counters
This is the wiki page for the perf performance counters subsystem in Linux. Performance counters are CPU hardware registers that count hardware events such as instructions executed, cache-misses suffered, or branches mispredicted. They form a basis for profiling applications to trace dynamic control flow and identify hotspots.
perf provides rich generalized abstractions over hardware specific capabilities. Among others, it provides per task, per CPU and per-workload counters, counter groups, and sampling capabilities on top of those. The userspace perf tools present a simple to use interface with commands like
- perf stat: obtain event counts
- perf record: record events for later reporting
- perf report: break down events by process, function, etc.
- perf annotate: annotate assembly or source code with event counts
- perf top: see live event count
To learn more, see the examples in the Tutorial.