Commit 12690401 authored Oct 05, 2025 by Ian Rogers Committed by Namhyung Kim Oct 13, 2025

perf stat: Additional verbose details for <not supported> events



If an event shows as "<not supported>" in perf stat output, in verbose
mode add the strerror output to help diagnose the issue.

Consider:
```
$ perf stat -e cycles,data_read,instructions true

 Performance counter stats for 'true':

           357,457      cycles:u
   <not supported> MiB  data_read:u
           156,182      instructions:u                   #    0.44  insn per cycle

       0.001250315 seconds time elapsed

       0.001283000 seconds user
       0.000000000 seconds sys
```

To understand why the data_read uncore event failed you can run it
again with -v option.  This change adds detailed message about the
error and suggestion how to fix it potentially.

  Warning:
  data_read:u event is not supported by the kernel.
  Invalid event (data_read:u) in per-thread mode, enable system wide with '-a'.

Signed-off-by: Ian Rogers <irogers@google.com>
[ simplified the commit message ]
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

parent 4b5dafe6

tools/perf/builtin-stat.c

+7 −5

Original line number	Diff line number	Diff line
		@@ -624,8 +624,9 @@ static enum counter_recovery stat_handle_error(struct evsel *counter, int err)
		*/
		if (err == EINVAL \|\| err == ENOSYS \|\| err == ENOENT \|\| err == ENXIO) {
		if (verbose > 0) {
		ui__warning("%s event is not supported by the kernel.\n",
		evsel__name(counter));
		evsel__open_strerror(counter, &target, err, msg, sizeof(msg));
		ui__warning("%s event is not supported by the kernel.\n%s\n",
		evsel__name(counter), msg);
		}
		return COUNTER_SKIP;
		}
		@@ -649,10 +650,11 @@ static enum counter_recovery stat_handle_error(struct evsel *counter, int err)
		}
		}
		if (verbose > 0) {
		evsel__open_strerror(counter, &target, err, msg, sizeof(msg));
		ui__warning(err == EOPNOTSUPP
		? "%s event is not supported by the kernel.\n"
		: "skipping event %s that kernel failed to open.\n",
		evsel__name(counter));
		? "%s event is not supported by the kernel.\n%s\n"
		: "skipping event %s that kernel failed to open.\n%s\n",
		evsel__name(counter), msg);
		}
		return COUNTER_SKIP;
		}