perf top: Add error message for EMFILE

When a user tries to open so many events, perf_event_open syscall may
fail with EMFILE. Provide advise for that case.

Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1325957132-10600-3-git-send-email-namhyung@gmail.com
Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index d89dec9..8f80df8 100644 (file)
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -888,6 +888,10 @@ try_again:
                                ui__warning("The %s event is not supported.\n",
                                            event_name(counter));
                                goto out_err;
+                       } else if (err == EMFILE) {
+                               ui__warning("Too many events are opened.\n"
+                                           "Try again after reducing the number of events\n");
+                               goto out_err;
                        }
 
                        ui__warning("The sys_perf_event_open() syscall "