[tip:perf/core] perf record: Print event causing perf_event_open() to fail

[tip-bot for Stephane Eranian]

Commit-ID:  1863fbbb781b1129da0cfdad46ef875370a34117
Gitweb:     http://git.kernel.org/tip/1863fbbb781b1129da0cfdad46ef875370a34117
Author:     Stephane Eranian <eranian@xxxxxxxxxx>
AuthorDate: Thu, 20 Sep 2012 18:19:45 +0200
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Thu, 20 Sep 2012 14:44:17 -0300

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@xxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20120920161945.GA7064@quad
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/builtin-record.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

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 @@ 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 &&
--
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