Attach to running process

Profile an already-running process for 5 seconds

perf record -p 1234 sleep 5
tool
perf17 commands
tags
perfprofilingattachpid

More perf commands

  • Live CPU flame call graph
    perf top -g --call-graph dwarf

    Live top hot functions with caller chains; dwarf unwind works without frame pointers

  • System-wide sampled record
    perf record -F 99 -a -g -- sleep 30 && perf report --stdio

    Sample whole machine at 99Hz for 30s, then print collapsed report; 99Hz dodges lockstep aliasing

  • Flame graph pipeline
    perf script | stackcollapse-perf.pl | flamegraph.pl > flame.svg

    Turn perf.data into an interactive flame graph SVG (Brendan Gregg FlameGraph tools)

  • Detailed counter stats
    perf stat -d -d -d -- ./app

    Run with three -d for L1/LLC/TLB and stalled-cycle detail; reveals memory-bound vs CPU-bound

  • Scheduler latency analysis
    perf sched record -- sleep 10 && perf sched latency --sort max

    Record context switches then show per-task wakeup latency; find runqueue starvation

all 17 perf commands