perf test: Add --metric-only to perf stat output tests

Add a test case for --metric-only for std, csv, json output mode using
shadow IPC metric from instructions and cycles events.  It should
produce 'insn per cycle' metric.

But currently JSON output has (none) 'GHz' as well.  It looks like a bug
but I don't have enough time to debug it for now so I made it pass. :(

  $ perf stat --metric-only -e instructions,cycles true

   Performance counter stats for 'true':

                    0.56

         0.002127319 seconds time elapsed

         0.002077000 seconds user
         0.000000000 seconds sys

  $ perf stat -x, --metric-only -e instructions,cycles true

  0.55,,

  $ perf stat -j --metric-only -e instructions,cycles true
  {"insn per cycle" : "0.53", "GHz" : "none"}

  $ perf test output -v
    5: Test data source output                                         : Ok
   31: Sort output of hist entries                                     : Ok
   88: perf stat CSV output linter                                     : Ok
   90: perf stat JSON output linter                                    : Ok
   92: perf stat STD output linter                                     : Ok

Tested-by: Thomas Falcon <thomas.falcon@intel.com>
Link: https://lore.kernel.org/r/20250304022837.1877845-2-namhyung@kernel.org
Suggested-by: Ian Rogers <irogers@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

tools/perf/tests/shell/lib/perf_json_output_lint.py

@@ -19,6 +19,7 @@ ap.add_argument('--per-cluster', action='store_true')
 ap.add_argument('--per-die', action='store_true')
 ap.add_argument('--per-node', action='store_true')
 ap.add_argument('--per-socket', action='store_true')
+ap.add_argument('--metric-only', action='store_true')
 ap.add_argument('--file', type=argparse.FileType('r'), default=sys.stdin)
 args = ap.parse_args()
 
@@ -64,6 +65,8 @@ def check_json_output(expected_items):
       'socket': lambda x: True,
       'thread': lambda x: True,
       'unit': lambda x: True,
+      'insn per cycle': lambda x: isfloat(x),
+      'GHz': lambda x: True,  # FIXME: it seems unintended for --metric-only
   }
   input = '[\n' + ','.join(Lines) + '\n]'
   for item in json.loads(input):
@@ -78,6 +81,8 @@ def check_json_output(expected_items):
         pass
       elif count - 1 in expected_items and 'metric-threshold' in item:
           pass
+      elif count in expected_items and 'insn per cycle' in item:
+          pass
       elif count not in expected_items:
         raise RuntimeError(f'wrong number of fields. counted {count} expected {expected_items}'
                            f' in \'{item}\'')
@@ -95,6 +100,8 @@ try:
     expected_items = [6, 8]
   elif args.per_core or args.per_socket or args.per_node or args.per_die or args.per_cluster or args.per_cache:
     expected_items = [7, 9]
+  elif args.metric_only:
+    expected_items = [1, 2]
   else:
     # If no option is specified, don't check the number of items.
     expected_items = -1

tools/perf/tests/shell/lib/stat_output.sh

@@ -148,6 +148,14 @@ check_per_socket()
 	echo "[Success]"
 }
 
+check_metric_only()
+{
+	echo -n "Checking $1 output: metric only "
+	perf stat --metric-only $2 -e instructions,cycles true
+	commachecker --metric-only
+	echo "[Success]"
+}
+
 # The perf stat options for per-socket, per-core, per-die
 # and -A ( no_aggr mode ) uses the info fetched from this
 # directory: "/sys/devices/system/cpu/cpu*/topology". For

tools/perf/tests/shell/stat+csv_output.sh

@@ -44,6 +44,7 @@ function commachecker()
 	;; "--per-die")		exp=8
 	;; "--per-cluster")	exp=8
 	;; "--per-cache")	exp=8
+	;; "--metric-only")	exp=2
 	esac
 
 	while read line
@@ -75,6 +76,7 @@ check_interval "CSV" "$perf_cmd"
 check_event "CSV" "$perf_cmd"
 check_per_thread "CSV" "$perf_cmd"
 check_per_node "CSV" "$perf_cmd"
+check_metric_only "CSV" "$perf_cmd"
 if [ $skip_test -ne 1 ]
 then
 	check_system_wide_no_aggr "CSV" "$perf_cmd"

tools/perf/tests/shell/stat+json_output.sh

@@ -173,6 +173,14 @@ check_per_socket()
 	echo "[Success]"
 }
 
+check_metric_only()
+{
+	echo -n "Checking json output: metric only "
+	perf stat -j --metric-only -e instructions,cycles -o "${stat_output}" true
+	$PYTHON $pythonchecker --metric-only --file "${stat_output}"
+	echo "[Success]"
+}
+
 # The perf stat options for per-socket, per-core, per-die
 # and -A ( no_aggr mode ) uses the info fetched from this
 # directory: "/sys/devices/system/cpu/cpu*/topology". For
@@ -207,6 +215,7 @@ check_interval
 check_event
 check_per_thread
 check_per_node
+check_metric_only
 if [ $skip_test -ne 1 ]
 then
 	check_system_wide_no_aggr

tools/perf/tests/shell/stat+std_output.sh

@@ -30,6 +30,7 @@ trap trap_cleanup EXIT TERM INT
 function commachecker()
 {
 	local prefix=1
+	local -i metric_only=0
 
 	case "$1"
 	in "--interval")	prefix=2
@@ -41,6 +42,7 @@ function commachecker()
 	;; "--per-die")		prefix=3
 	;; "--per-cache")	prefix=3
 	;; "--per-cluster")	prefix=3
+	;; "--metric-only")	metric_only=1
 	esac
 
 	while read line
@@ -60,6 +62,9 @@ function commachecker()
 		x=${main_body%#*}
 		[ "$x" = "" ] && continue
 
+		# Check metric only - if it has a non-empty result
+		[ $metric_only -eq 1 ] && return 0
+
 		# Skip metrics without event name
 		y=${main_body#*#}
 		for i in "${!skip_metric[@]}"; do
@@ -84,6 +89,8 @@ function commachecker()
 			exit 1;
 		}
 	done < "${stat_output}"
+
+	[ $metric_only -eq 1 ] && exit 1
 	return 0
 }
 
@@ -95,6 +102,7 @@ check_system_wide "STD" "$perf_cmd"
 check_interval "STD" "$perf_cmd"
 check_per_thread "STD" "$perf_cmd"
 check_per_node "STD" "$perf_cmd"
+check_metric_only "STD" "$perf_cmd"
 if [ $skip_test -ne 1 ]
 then
 	check_system_wide_no_aggr "STD" "$perf_cmd"