Install and run perf

Most Linux distros enable perf_events subsystem in kernel and ship perf utility by default. If not, the distro should provide package already. E.g., On Arch Linux, setting up perf is easy: 

  1. # pacman -S perf

BTW, Acme is the maintainer of perf, so you can always build and try state-of-the-art feature from his perf/core branch: 

  1. # git clone git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux -b perf/core
  2. # cd linux/tools/perf
  3. # make menuconfig
  4. # make

When perf is ready, you can launch it in terminal: 

  1. # perf
  3.  usage: perf [--version] [--help] [OPTIONS] COMMAND [ARGS]
  5.  The most commonly used perf commands are:
  6.    annotate        Read perf.data (created by perf record) and display annotated code
  7.    archive         Create archive with object files with build-ids found in perf.data file
  8.    bench           General framework for benchmark suites
  9. ......

This will list all supported perf commands (The main function code of perf is here).

There is a /proc/sys/kernel/perf_event_paranoid file which controls use of the performance events system by unprivileged users (without CAP_SYS_ADMIN), and the default value is 2: 

  1. # cat  /proc/sys/kernel/perf_event_paranoid
  2. 2

The meaning of its value is like following:

-1: Allow use of (almost) all events by all users
Ignore mlock limit after perf_event_mlock_kb without CAP_IPC_LOCK
>=0: Disallow ftrace function tracepoint by users without CAP_SYS_ADMIN
Disallow raw tracepoint access by users without CAP_SYS_ADMIN
>=1: Disallow CPU event access by users without CAP_SYS_ADMIN
>=2: Disallow kernel profiling by users without CAP_SYS_ADMIN

This means you may not use some functions of perf if you are not privileged user (e.g., perf mem). So if you meet something strange, such as perf can’t sample data, please try run as privileged user (i.e., sudo) or check the value of /proc/sys/kernel/perf_event_paranoid file.