The 'perf stat' subcommand supports the request for a summary of the
interval counter readings.  But the summary lines break the CSV output
so it's hard for scripts to parse the result.

Before:

  # perf stat -x, -I1000 --interval-count 1 --summary
       1.001323097,8013.48,msec,cpu-clock,8013483384,100.00,8.013,CPUs utilized
       1.001323097,270,,context-switches,8013513297,100.00,0.034,K/sec
       1.001323097,13,,cpu-migrations,8013530032,100.00,0.002,K/sec
       1.001323097,184,,page-faults,8013546992,100.00,0.023,K/sec
       1.001323097,20574191,,cycles,8013551506,100.00,0.003,GHz
       1.001323097,10562267,,instructions,8013564958,100.00,0.51,insn per cycle
       1.001323097,2019244,,branches,8013575673,100.00,0.252,M/sec
       1.001323097,106152,,branch-misses,8013585776,100.00,5.26,of all branches
  8013.48,msec,cpu-clock,8013483384,100.00,7.984,CPUs utilized
  270,,context-switches,8013513297,100.00,0.034,K/sec
  13,,cpu-migrations,8013530032,100.00,0.002,K/sec
  184,,page-faults,8013546992,100.00,0.023,K/sec
  20574191,,cycles,8013551506,100.00,0.003,GHz
  10562267,,instructions,8013564958,100.00,0.51,insn per cycle
  2019244,,branches,8013575673,100.00,0.252,M/sec
  106152,,branch-misses,8013585776,100.00,5.26,of all branches

The summary line loses the timestamp column, which breaks the CSV
output.

We add a column at the original 'timestamp' position and it just says
'summary' for the summary line.

After:

  # perf stat -x, -I1000 --interval-count 1 --summary
       1.001196053,8012.72,msec,cpu-clock,8012722903,100.00,8.013,CPUs utilized
       1.001196053,218,,context-switches,8012753271,100.00,0.027,K/sec
       1.001196053,9,,cpu-migrations,8012769767,100.00,0.001,K/sec
       1.001196053,0,,page-faults,8012786257,100.00,0.000,K/sec
       1.001196053,15004518,,cycles,8012790637,100.00,0.002,GHz
       1.001196053,7954691,,instructions,8012804027,100.00,0.53,insn per cycle
       1.001196053,1590259,,branches,8012814766,100.00,0.198,M/sec
       1.001196053,82601,,branch-misses,8012824365,100.00,5.19,of all branches
           summary,8012.72,msec,cpu-clock,8012722903,100.00,7.986,CPUs utilized
           summary,218,,context-switches,8012753271,100.00,0.027,K/sec
           summary,9,,cpu-migrations,8012769767,100.00,0.001,K/sec
           summary,0,,page-faults,8012786257,100.00,0.000,K/sec
           summary,15004518,,cycles,8012790637,100.00,0.002,GHz
           summary,7954691,,instructions,8012804027,100.00,0.53,insn per cycle
           summary,1590259,,branches,8012814766,100.00,0.198,M/sec
           summary,82601,,branch-misses,8012824365,100.00,5.19,of all branches

Now it's easy for script to analyse the summary lines.

Of course, we also consider not to break possible existing scripts which
can continue to use the broken CSV format by using a new '--no-csv-summary.'
option.

  # perf stat -x, -I1000 --interval-count 1 --summary --no-csv-summary
       1.001213261,8012.67,msec,cpu-clock,8012672327,100.00,8.013,CPUs utilized
       1.001213261,197,,context-switches,8012703742,100.00,24.586,/sec
       1.001213261,9,,cpu-migrations,8012720902,100.00,1.123,/sec
       1.001213261,644,,page-faults,8012738266,100.00,80.373,/sec
       1.001213261,18350698,,cycles,8012744109,100.00,0.002,GHz
       1.001213261,12745021,,instructions,8012759001,100.00,0.69,insn per cycle
       1.001213261,2458033,,branches,8012770864,100.00,306.768,K/sec
       1.001213261,102107,,branch-misses,8012781751,100.00,4.15,of all branches
  8012.67,msec,cpu-clock,8012672327,100.00,7.985,CPUs utilized
  197,,context-switches,8012703742,100.00,24.586,/sec
  9,,cpu-migrations,8012720902,100.00,1.123,/sec
  644,,page-faults,8012738266,100.00,80.373,/sec
  18350698,,cycles,8012744109,100.00,0.002,GHz
  12745021,,instructions,8012759001,100.00,0.69,insn per cycle
  2458033,,branches,8012770864,100.00,306.768,K/sec
  102107,,branch-misses,8012781751,100.00,4.15,of all branches

This option can be enabled in perf config by setting the variable
'stat.no-csv-summary'.

  # perf config stat.no-csv-summary=true

  # perf config -l
  stat.no-csv-summary=true

  # perf stat -x, -I1000 --interval-count 1 --summary
       1.001330198,8013.28,msec,cpu-clock,8013279201,100.00,8.013,CPUs utilized
       1.001330198,205,,context-switches,8013308394,100.00,25.583,/sec
       1.001330198,10,,cpu-migrations,8013324681,100.00,1.248,/sec
       1.001330198,0,,page-faults,8013340926,100.00,0.000,/sec
       1.001330198,8027742,,cycles,8013344503,100.00,0.001,GHz
       1.001330198,2871717,,instructions,8013356501,100.00,0.36,insn per cycle
       1.001330198,553564,,branches,8013366204,100.00,69.081,K/sec
       1.001330198,54021,,branch-misses,8013375952,100.00,9.76,of all branches
  8013.28,msec,cpu-clock,8013279201,100.00,7.985,CPUs utilized
  205,,context-switches,8013308394,100.00,25.583,/sec
  10,,cpu-migrations,8013324681,100.00,1.248,/sec
  0,,page-faults,8013340926,100.00,0.000,/sec
  8027742,,cycles,8013344503,100.00,0.001,GHz
  2871717,,instructions,8013356501,100.00,0.36,insn per cycle
  553564,,branches,8013366204,100.00,69.081,K/sec
  54021,,branch-misses,8013375952,100.00,9.76,of all branches
Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Acked-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jin Yao <yao.jin@intel.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20210319070156.20394-1-yao.jin@linux.intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>