perf

perf is a performance analyzing tool for Linux-based systems. Available via command-line interface, it is capable of statistical profiling of the entire system (both kernel and user code).

Commands

  • To list the supported commands, execute

    perf
     usage: perf [--version] [--help] [OPTIONS] COMMAND [ARGS]

 The most commonly used perf commands are:
   annotate        Read perf.data (created by perf record) and display annotated code
   archive         Create archive with object files with build-ids found in perf.data file
   bench           General framework for benchmark suites
   buildid-cache   Manage build-id cache.
   buildid-list    List the buildids in a perf.data file
   config          Get and set variables in a configuration file.
   data            Data file related processing
   diff            Read perf.data files and display the differential profile
   evlist          List the event names in a perf.data file
   inject          Filter to augment the events stream with additional information
   kmem            Tool to trace/measure kernel memory properties
   kvm             Tool to trace/measure kvm guest os
   list            List all symbolic event types
   lock            Analyze lock events
   mem             Profile memory accesses
   record          Run a command and record its profile into perf.data
   report          Read perf.data (created by perf record) and display the profile
   sched           Tool to trace/measure scheduler properties (latencies)
   script          Read perf.data (created by perf record) and display trace output
   stat            Run a command and gather performance counter statistics
   test            Runs sanity tests.
   timechart       Tool to visualize total system behavior during a workload
   top             System profiling tool.
   probe           Define new dynamic tracepoints
   trace           strace inspired tool

    Certain commands require special support in the kernel and may not be available.

  • To obtain the list of options for each command, simply type the command name followed by -h:

    perf record -h

Sampling

  • There are several commands associated with sampling: record, report and annotate. You must first collect the samples using perf record. This generates an output binary file called perf.data. That file can then be analyzed, possibly on another machine, using the perf report and perf annotate commands.

    perf record -F 1000 --call-graph dwarf -e cycles:u ./program
    perf report

    By default, samples are sorted by functions with the most samples first.

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