perf stat: Avoid printing cpus with no counters

perf_evlist's user_requested_cpus can contain CPUs not present in any
evsel's cpus, for example uncore counters. Avoid printing the prefix and
trailing \n until the first valid counter is encountered.

Reviewed-by: Adrian Hunter <[email protected]>
Signed-off-by: Ian Rogers <[email protected]>
Cc: Alexander Antonov <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Alexei Starovoitov <[email protected]>
Cc: Alexey Bayduraev <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Andrii Nakryiko <[email protected]>
Cc: Daniel Borkmann <[email protected]>
Cc: German Gomez <[email protected]>
Cc: James Clark <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: John Fastabend <[email protected]>
Cc: John Garry <[email protected]>
Cc: KP Singh <[email protected]>
Cc: Kajol Jain <[email protected]>
Cc: Leo Yan <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Martin KaFai Lau <[email protected]>
Cc: Mathieu Poirier <[email protected]>
Cc: Mike Leach <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Riccardo Mancini <[email protected]>
Cc: Song Liu <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: Suzuki Poulouse <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Yonghong Song <[email protected]>
Link: http://lore.kernel.org/lkml/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

1 files changed, 4 insertions, 3 deletions

diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
index d9629a83aa78..13f705737367 100644
--- a/tools/perf/util/stat-display.c
+++ b/tools/perf/util/stat-display.c
@@ -948,8 +948,6 @@ static void print_no_aggr_metric(struct perf_stat_config *config,
 		struct evsel *counter;
 		bool first = true;
 
-		if (prefix)
-			fputs(prefix, config->output);
 		evlist__for_each_entry(evlist, counter) {
 			u64 ena, run, val;
 			double uval;
@@ -961,6 +959,8 @@ static void print_no_aggr_metric(struct perf_stat_config *config,
 
 			id = aggr_cpu_id__cpu(cpu, /*data=*/NULL);
 			if (first) {
+				if (prefix)
+					fputs(prefix, config->output);
 				aggr_printout(config, counter, id, 0);
 				first = false;
 			}
@@ -972,7 +972,8 @@ static void print_no_aggr_metric(struct perf_stat_config *config,
 			printout(config, id, 0, counter, uval, prefix,
 				 run, ena, 1.0, &rt_stat);
 		}
-		fputc('\n', config->output);
+		if (!first)
+			fputc('\n', config->output);
 	}
 }