[PATCH 0/4] perf ftrace: Add 'profile' subcommand (v1)

[Namhyung Kim <namhyung@kernel.org>]

Hello,

This is an attempt to extend perf ftrace command to show a kernel function
profile using the function_graph tracer.  This is useful to see detailed
info like total, average, max time (in usec) and number of calls for each
function.

  $ sudo perf ftrace profile -- sync | head
  # Total (us)   Avg (us)   Max (us)      Count   Function
      7638.372   7638.372   7638.372          1   __do_sys_sync
      7638.059   7638.059   7638.059          1   ksys_sync
      5893.959   1964.653   3747.963          3   iterate_supers
      5214.181    579.353   1688.752          9   schedule
      3585.773     44.269   3537.329         81   sync_inodes_one_sb
      3566.179     44.027   3537.078         81   sync_inodes_sb
      1976.901    247.113   1968.070          8   filemap_fdatawait_keep_errors
      1974.367    246.796   1967.895          8   __filemap_fdatawait_range
      1935.407     37.219   1157.627         52   folio_wait_writeback

While the kernel also provides the similar functionality IIRC under
CONFIG_FUNCTION_PROFILER, it's often not enabled on disto kernels so I
implemented it in user space.

Also it can support function filters like 'perf ftrace trace' so users
can focus on some target functions and change the buffer size if needed.

  $ sudo perf ftrace profile -h
  
   Usage: perf ftrace [<options>] [<command>]
      or: perf ftrace [<options>] -- [<command>] [<options>]
      or: perf ftrace {trace|latency|profile} [<options>] [<command>]
      or: perf ftrace {trace|latency|profile} [<options>] -- [<command>] [<options>]
  
      -a, --all-cpus        System-wide collection from all CPUs
      -C, --cpu <cpu>       List of cpus to monitor
      -G, --graph-funcs <func>
                            Trace given functions using function_graph tracer
      -g, --nograph-funcs <func>
                            Set nograph filter on given functions
      -m, --buffer-size <size>
                            Size of per cpu buffer, needs to use a B, K, M or G suffix.
      -N, --notrace-funcs <func>
                            Do not trace given functions
      -p, --pid <pid>       Trace on existing process id
      -s, --sort <key>      Sort result by key: total (default), avg, max, count, name.
      -T, --trace-funcs <func>
                            Trace given functions using function tracer
      -v, --verbose         Be more verbose
          --tid <tid>       Trace on existing thread id (exclusive to --pid)


The code is also available in 'perf/ftrace-profile-v1' branch at
git://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git

Thanks,
Namhyung


Namhyung Kim (4):
  perf ftrace: Add 'tail' option to --graph-opts
  perf ftrace: Factor out check_ftrace_capable()
  perf ftrace: Add 'profile' command
  perf ftrace: Add -s/--sort option to profile sub-command

 tools/perf/Documentation/perf-ftrace.txt |  48 ++-
 tools/perf/builtin-ftrace.c              | 439 +++++++++++++++++++++--
 tools/perf/util/ftrace.h                 |   3 +
 3 files changed, 463 insertions(+), 27 deletions(-)

-- 
2.46.0.rc1.232.g9752f9e123-goog