perf tools: Emit clearer message for sys_perf_event_open ENOENT return

Resend of patch sent back in January 2011 in light of recent confusion around
unsupported events for a given platform.

Improve sys_perf_event_open ENOENT return handling in top and record, just
like 5a3446b does for stat.

Retry of Arnaldo's patch using ui_warning instead of die which allows the
fallback from hardware cycles to software clock.

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
LKML-Reference: <1301080271-20945-1-git-send-email-daahern@cisco.com>
Signed-off-by: David Ahern <daahern@cisco.com>
[ committer note: Some adjustments to make it apply to newer codebase ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

2 files changed, 15 insertions, 1 deletions

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 623695e18254..db6adecf46f1 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -301,11 +301,19 @@ try_again:
                                         && attr->config == PERF_COUNT_HW_CPU_CYCLES) {
 
                                 if (verbose)
-                                        warning(" ... trying to fall back to cpu-clock-ticks\n");
+                                        ui__warning("The cycles event is not supported, "
+                                                    "trying to fall back to cpu-clock-ticks\n");
                                 attr->type = PERF_TYPE_SOFTWARE;
                                 attr->config = PERF_COUNT_SW_CPU_CLOCK;
                                 goto try_again;
                         }
+
+                        if (err == ENOENT) {
+                                ui__warning("The %s event is not supported.\n",
+                                            event_name(pos));
+                                exit(EXIT_FAILURE);
+                        }
+
                         printf("\n");
                         error("sys_perf_event_open() syscall returned with %d (%s).  /bin/dmesg may provide additional information.\n",
                               err, strerror(err));
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index 935fc4fd878e..fc1273e976c5 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -870,6 +870,12 @@ try_again:
                                 goto try_again;
                         }
 
+                        if (err == ENOENT) {
+                                ui__warning("The %s event is not supported.\n",
+                                            event_name(counter));
+                                goto out_err;
+                        }
+
                         ui__warning("The sys_perf_event_open() syscall "
                                     "returned with %d (%s).  /bin/dmesg "
                                     "may provide additional information.\n"