Re: [PATCH] perf, tools, stat: Print warning when no metric with --metric-only

[Jiri Olsa]

On Thu, Mar 10, 2016 at 06:27:17AM -0800, Andi Kleen wrote:
> From: Andi Kleen <ak@xxxxxxxxxxxxxxx>
> 
> Print a warning when --metric-only is specified, but the events
> define no metric. Requested by Jiri.
> 
> % perf stat -e cycles --metric-only true
> 
>  Performance counter stats for 'true':
> 
> No metrics defined by configured events
> 
>        0.001612070 seconds time elapsed
> 

how about printing the 'time' column and keeping the warning on the header line?


[jolsa@krava perf]$ sudo ./perf stat -a -I 1000 --metric-only 
            time insn per cycle       branch-misses of all branches 
     1.000370422    0.30                6.77%                      
     2.000749536    0.40                5.75%                      
     3.001007542    0.28                5.38%                      
     4.001324779    0.57                5.83%                      
^C     4.011558899    0.01                0.12%                      

[jolsa@krava perf]$ sudo ./perf stat -a -I 1000 --metric-only -e cycles
            time No metrics defined by configured events
     1.000211156 
     2.000432519 


thanks,
jirka


---
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 91188047be6a..9ce4138a8065 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -1302,7 +1302,7 @@ static void print_metric_headers(char *prefix)
 	};
 
 	if (prefix)
-		fprintf(stat_config.output, "%s", prefix);
+		fprintf(stat_config.output, "%16s ", "time");
 
 	if (!csv_output)
 		fprintf(stat_config.output, "%*s",
@@ -1319,9 +1319,9 @@ static void print_metric_headers(char *prefix)
 					      0,
 					      &out);
 	}
-	fputc('\n', stat_config.output);
 	if (os.nheaders == 0)
-		pr_warning("No metrics defined by configured events\n");
+		pr_warning("No metrics defined by configured events");
+	fputc('\n', stat_config.output);
 }
 
 static void print_interval(char *prefix, struct timespec *ts)