[PATCH V2] tools/perf: Fix printing field separator in CSV metrics output

[Athira Rajeev]

In perf stat with CSV output option, number of fields
in metrics output is not matching with number of fields
in other event output lines.

Sample output below after applying patch to fix
printing os->prefix.

	# ./perf stat -x, --per-socket -a -C 1 ls
	S0,1,1.89,msec,cpu-clock,1887692,100.00,1.013,CPUs utilized
	S0,1,2,,context-switches,1885842,100.00,1.060,K/sec
	S0,1,0,,cpu-migrations,1885374,100.00,0.000,/sec
	S0,1,2,,page-faults,1884880,100.00,1.060,K/sec
	S0,1,189544,,cycles,1263158,67.00,0.100,GHz
	S0,1,64602,,stalled-cycles-frontend,1876146,100.00,34.08,frontend cycles idle
	S0,1,128241,,stalled-cycles-backend,1875512,100.00,67.66,backend cycles idle
	S0,1,95578,,instructions,1874676,100.00,0.50,insn per cycle
===>	S0,1,,,,,,,1.34,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 more separators.
Each csv output line is expected to have 8 field
separatorsi (for the 9 fields), where as last line
has 10 "," in the result. Patch fixes this issue.

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 fields printed in each line contains:
"Socket_id,aggr nr,Avg,unit,event_name,run,enable_percent,ratio,unit"

The metric output prints Socket_id, aggr nr, ratio
and unit. It has to skip through remaining five fields
ie, Avg,unit,event_name,run,enable_percent. The csv
line callback uses "os->nfields" to know the number of
fields to skip to match with other lines.
Currently it is set as:
	os.nfields = 3 + aggr_fields[config->aggr_mode] + (counter->cgrp ? 1 : 0);

But in case of aggregation modes, csv_sep already
gets printed along with each field (Function "aggr_printout"
in util/stat-display.c). So aggr_fields can be
removed from nfields. And fixed number of fields to
skip has to be "4". This is to skip fields for:
"avg, unit, event name, run, enable_percent"
Example from line for instructions:
"1.89,msec,cpu-clock,1887692,100.00"

This needs 4 csv separators. Patch removes aggr_fields
and uses 4 as fixed number of os->nfields to skip.

After the patch:

	# ./perf stat -x, --per-socket -a -C 1 ls
	S0,1,1.92,msec,cpu-clock,1917648,100.00,1.010,CPUs utilized
	S0,1,54,,context-switches,1916762,100.00,28.176,K/sec
	-------
	S0,1,528693,,instructions,1908854,100.00,0.36,insn per cycle
	S0,1,,,,,,1.81,stalled cycles per insn

Fixes: 92a61f6412d3 ("perf stat: Implement CSV metrics output")
Reported-by: Disha Goel <disgoel at linux.vnet.ibm.com>
Reviewed-By: Kajol Jain <kjain at linux.ibm.com>
Tested-by: Disha Goel<disgoel at linux.vnet.ibm.com>
Signed-off-by: Athira Rajeev <atrajeev at linux.vnet.ibm.com>
---
Changelog:
- Rebased on top of latest source.
- Added Reviewed-by and Tested-by from Kajol and
  Disha.

 tools/perf/util/stat-display.c | 13 +------------
 1 file changed, 1 insertion(+), 12 deletions(-)

diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
index ba66bb7fc1ca..5ce14bf18055 100644
--- a/tools/perf/util/stat-display.c
+++ b/tools/perf/util/stat-display.c
@@ -551,20 +551,9 @@ static void printout(struct perf_stat_config *config, struct aggr_cpu_id id, int
 	new_line_t nl;
 
 	if (config->csv_output) {
-		static const int aggr_fields[AGGR_MAX] = {
-			[AGGR_NONE] = 1,
-			[AGGR_GLOBAL] = 0,
-			[AGGR_SOCKET] = 2,
-			[AGGR_DIE] = 2,
-			[AGGR_CORE] = 2,
-			[AGGR_THREAD] = 1,
-			[AGGR_UNSET] = 0,
-			[AGGR_NODE] = 1,
-		};
-
 		pm = config->metric_only ? print_metric_only_csv : print_metric_csv;
 		nl = config->metric_only ? new_line_metric : new_line_csv;
-		os.nfields = 3 + aggr_fields[config->aggr_mode] + (counter->cgrp ? 1 : 0);
+		os.nfields = 4 + (counter->cgrp ? 1 : 0);
 	} else if (config->json_output) {
 		pm = config->metric_only ? print_metric_only_json : print_metric_json;
 		nl = config->metric_only ? new_line_metric : new_line_json;
-- 
2.31.1