From: Athira Rajeev atrajeev@linux.vnet.ibm.com
[ Upstream commit ad353b710c7493df3d4fc2d3a51819126bed2e81 ]
'perf stat' with CSV output option prints an extra empty string as first field in metrics output line. Sample output below:
# ./perf stat -x, --per-socket -a -C 1 ls S0,1,1.78,msec,cpu-clock,1785146,100.00,0.973,CPUs utilized S0,1,26,,context-switches,1781750,100.00,0.015,M/sec S0,1,1,,cpu-migrations,1780526,100.00,0.561,K/sec S0,1,1,,page-faults,1779060,100.00,0.561,K/sec S0,1,875807,,cycles,1769826,100.00,0.491,GHz S0,1,85281,,stalled-cycles-frontend,1767512,100.00,9.74,frontend cycles idle S0,1,576839,,stalled-cycles-backend,1766260,100.00,65.86,backend cycles idle S0,1,288430,,instructions,1762246,100.00,0.33,insn per cycle ====> ,S0,1,,,,,,,2.00,stalled cycles per insn
The above command line uses field separator as "," via "-x," option and per-socket option displays socket value as first field. But here the last line for "stalled cycles per insn" has "," in the beginning.
Sample output using interval mode:
# ./perf stat -I 1000 -x, --per-socket -a -C 1 ls 0.001813453,S0,1,1.87,msec,cpu-clock,1872052,100.00,0.002,CPUs utilized 0.001813453,S0,1,2,,context-switches,1868028,100.00,1.070,K/sec ------ 0.001813453,S0,1,85379,,instructions,1856754,100.00,0.32,insn per cycle ====> 0.001813453,,S0,1,,,,,,,1.34,stalled cycles per insn
Above result also has an extra CSV separator after the timestamp. Patch addresses extra field separator in the beginning of the metric output line.
The counter stats are displayed by function "perf_stat__print_shadow_stats" in code "util/stat-shadow.c". While printing the stats info for "stalled cycles per insn", function "new_line_csv" is used as new_line callback.
The new_line_csv function has check for "os->prefix" and if prefix is not null, it will be printed along with cvs separator. Snippet from "new_line_csv": if (os->prefix) fprintf(os->fh, "%s%s", os->prefix, config->csv_sep);
Here os->prefix gets printed followed by "," which is the cvs separator. The os->prefix is used in interval mode option ( -I ), to print time stamp on every new line. But prefix is already set to contain CSV separator when used in interval mode for CSV option.
Reference: Function "static void print_interval" Snippet: sprintf(prefix, "%6lu.%09lu%s", ts->tv_sec, ts->tv_nsec, config->csv_sep);
Also if prefix is not assigned (if not used with -I option), it gets set to empty string. Reference: function printout() in util/stat-display.c Snippet: .prefix = prefix ? prefix : "",
Since prefix already set to contain cvs_sep in interval option, patch removes printing config->csv_sep in new_line_csv function to avoid printing extra field.
After the patch:
# ./perf stat -x, --per-socket -a -C 1 ls S0,1,2.04,msec,cpu-clock,2045202,100.00,1.013,CPUs utilized S0,1,2,,context-switches,2041444,100.00,979.289,/sec S0,1,0,,cpu-migrations,2040820,100.00,0.000,/sec S0,1,2,,page-faults,2040288,100.00,979.289,/sec S0,1,254589,,cycles,2036066,100.00,0.125,GHz S0,1,82481,,stalled-cycles-frontend,2032420,100.00,32.40,frontend cycles idle S0,1,113170,,stalled-cycles-backend,2031722,100.00,44.45,backend cycles idle S0,1,88766,,instructions,2030942,100.00,0.35,insn per cycle S0,1,,,,,,,1.27,stalled cycles per insn
Fixes: 92a61f6412d3a09d ("perf stat: Implement CSV metrics output") Reported-by: Disha Goel disgoel@linux.vnet.ibm.com Reviewed-By: Kajol Jain kjain@linux.ibm.com Signed-off-by: Athira Jajeev atrajeev@linux.vnet.ibm.com Tested-by: Disha Goel disgoel@linux.vnet.ibm.com Cc: Andi Kleen ak@linux.intel.com Cc: Ian Rogers irogers@google.com Cc: James Clark james.clark@arm.com Cc: Jiri Olsa jolsa@kernel.org Cc: linuxppc-dev@lists.ozlabs.org Cc: Madhavan Srinivasan maddy@linux.vnet.ibm.com Cc: Michael Ellerman mpe@ellerman.id.au Cc: Nageswara R Sastry rnsastry@linux.ibm.com Cc: Namhyung Kim namhyung@kernel.org Link: https://lore.kernel.org/r/20221018085605.63834-1-atrajeev@linux.vnet.ibm.com Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- tools/perf/util/stat-display.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c index aa9d9d2936e7..7c5f5219dbff 100644 --- a/tools/perf/util/stat-display.c +++ b/tools/perf/util/stat-display.c @@ -273,7 +273,7 @@ static void new_line_csv(struct perf_stat_config *config, void *ctx)
fputc('\n', os->fh); if (os->prefix) - fprintf(os->fh, "%s%s", os->prefix, config->csv_sep); + fprintf(os->fh, "%s", os->prefix); aggr_printout(config, os->evsel, os->id, os->nr); for (i = 0; i < os->nfields; i++) fputs(config->csv_sep, os->fh);