[PATCH] perf record: print event causing perf_event_open() to fail

[Stephane Eranian <eranian@google.com>]

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>
---

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index c643ed6..2cb7434 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -297,8 +297,10 @@ static int perf_record__open(struct perf_record *rec)
 			}
 
 			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 &&