perf record: Print event causing perf_event_open() to fail

Got tired of not getting the event that caused the perf_event_open()
syscall to fail. So I fixed the error message. This is very useful when
monitoring lots of events in a single run.

Signed-off-by: Stephane Eranian <eranian@google.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20120920161945.GA7064@quad
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index c643ed669ef9..2cb74343de3e 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -297,8 +297,10 @@ try_again:
                         }
 
                         printf("\n");
-                        error("sys_perf_event_open() syscall returned with %d (%s).  /bin/dmesg may provide additional information.\n",
-                              err, strerror(err));
+                        error("sys_perf_event_open() syscall returned with %d "
+                              "(%s) for event %s. /bin/dmesg may provide "
+                              "additional information.\n",
+                              err, strerror(err), perf_evsel__name(pos));
 
 #if defined(__i386__) || defined(__x86_64__)
                         if (attr->type == PERF_TYPE_HARDWARE &&