perf evsel: Improve error message for uncore events

When a group has multiple events and the leader fails it can yield
errors like:

  $ perf stat -e '{uncore_imc/cas_count_read/},instructions' /bin/true
  Error:
  The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (uncore_imc/cas_count_read/).
  /bin/dmesg | grep -i perf may provide additional information.

However, when not the group leader <not supported> is given:

  $ perf stat -e '{instructions,uncore_imc/cas_count_read/}' /bin/true
  ...
           1,619,057      instructions
     <not supported> MiB  uncore_imc/cas_count_read/

This is necessary because get_group_fd will fail if the leader fails and
is the direct result of the check on line 750 of builtin-stat.c in
stat_handle_error that returns COUNTER_SKIP for the latter case.

This patch improves the error message to:

  $ perf stat -e '{uncore_imc/cas_count_read/},instructions' /bin/true
  Error:
  Invalid event (uncore_imc/cas_count_read/) in per-thread mode, enable system wide with '-a'.

v2. Changed the test to use !target__has_cpu as suggested by Namhyung Kim.

Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: https://lore.kernel.org/r/20211223183948.3423989-2-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 656c30b..a0acf53 100644 (file)
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -2931,6 +2931,10 @@ int evsel__open_strerror(struct evsel *evsel, struct target *target,
                        return scnprintf(msg, size, "wrong clockid (%d).", clockid);
                if (perf_missing_features.aux_output)
                        return scnprintf(msg, size, "The 'aux_output' feature is not supported, update the kernel.");
+               if (!target__has_cpu(target))
+                       return scnprintf(msg, size,
+       "Invalid event (%s) in per-thread mode, enable system wide with '-a'.",
+                                       evsel__name(evsel));
                break;
        case ENODATA:
                return scnprintf(msg, size, "Cannot collect data source with the load latency event alone. "