perf record: Show precise number of samples
authorNamhyung Kim <namhyung@kernel.org>
Thu, 29 Jan 2015 08:06:44 +0000 (17:06 +0900)
committerArnaldo Carvalho de Melo <acme@redhat.com>
Thu, 29 Jan 2015 19:37:20 +0000 (16:37 -0300)
commite3d5911221f5cf71e1f0306256d4e42d34a365d2
tree2184bb4ec461ba141d8a89b2df2e63705d4cdfed
parent4ac30cf74b308fb01338e660d3471cd490a7958a
perf record: Show precise number of samples

After perf record finishes, it prints file size and number of samples in
the file but this info is wrong since it assumes typical sample size of
24 bytes and divides file size by the value.

However as we post-process recorded samples for build-id, it can show
correct number like below.  If build-id post-processing is not requested
just omit the wrong number of samples.

  $ perf record noploop 1
    [ perf record: Woken up 1 times to write data ]
    [ perf record: Captured and wrote 0.159 MB perf.data (3989 samples) ]

  $ perf report --stdio -n
  # To display the perf.data header info, please use --header/--header-only options.
  #
  # Samples: 3K of event 'cycles'
  # Event count (approx.): 3771330663
  #
  # Overhead       Samples  Command  Shared Object     Symbol
  # ........  ............  .......  ................  ..........................
  #
      99.90%          3982  noploop  noploop           [.] main
       0.09%             1  noploop  ld-2.17.so        [.] _dl_check_map_versions
       0.01%             1  noploop  [kernel.vmlinux]  [k] setup_arg_pages
       0.00%             5  noploop  [kernel.vmlinux]  [k] intel_pmu_enable_all

Reported-by: Milian Wolff <mail@milianw.de>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1422518843-25818-4-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
tools/perf/builtin-record.c