[PATCH 2/2] tools/perf: Fix printing field separator in CSV metrics output

[Athira Rajeev]

> On 18-Oct-2022, at 2:26 PM, Athira Rajeev <atrajeev at linux.vnet.ibm.com> wrote:
> 
> 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>
> Signed-off-by: Athira Rajeev <atrajeev at linux.vnet.ibm.com>

Hi All,

Looking for review comments for this change.

Thanks
Athira

> ---
> 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 879874a4bc07..5ca151adf826 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] = 0,
> -		};
> -
> 		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
>