[PATCH 5/5] perf record: Add -a as a default target

[Jiri Olsa <jolsa@kernel.org>]

Adding system wide (-a) option as a default target
if non is specified.

  # perf record
  Warning: No target specified, setting system-wide collection (-a).
  ...

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-tq11of2qlz8kxpxzva05d54l@git.kernel.org
---
 tools/perf/Documentation/perf-record.txt | 2 +-
 tools/perf/builtin-record.c              | 6 ++++--
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index 27256bc68eda..b16003ec14a7 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -157,7 +157,7 @@ OPTIONS
 
 -a::
 --all-cpus::
-        System-wide collection from all CPUs.
+        System-wide collection from all CPUs (default if no target is specified).
 
 -p::
 --pid=::
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 6cd6776052e7..dab23f6b10f3 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -1677,8 +1677,10 @@ int cmd_record(int argc, const char **argv, const char *prefix __maybe_unused)
 
 	argc = parse_options(argc, argv, record_options, record_usage,
 			    PARSE_OPT_STOP_AT_NON_OPTION);
-	if (!argc && target__none(&rec->opts.target))
-		usage_with_options(record_usage, record_options);
+	if (!argc && target__none(&rec->opts.target)) {
+		pr_warning("Warning: No target specified, setting system-wide collection (-a).\n");
+		rec->opts.target.system_wide = true;
+	}
 
 	if (nr_cgroups && !rec->opts.target.system_wide) {
 		usage_with_options_msg(record_usage, record_options,
-- 
2.7.4