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>

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 7006f848f87a6333f941b77629d95e87397feacf..84e06ec09cc270dee93336f1806d900e58b27bf9 100644 (file)
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -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;
 }