[tip:perf/core] perf record: Force enable --timestamp-filename when --switch-output is provided

[tip-bot for Wang Nan]

Commit-ID:  eca857ab381858450ec2f91f5aaae7f2f7a7a180
Gitweb:     http://git.kernel.org/tip/eca857ab381858450ec2f91f5aaae7f2f7a7a180
Author:     Wang Nan <wangnan0@xxxxxxxxxx>
AuthorDate: Wed, 20 Apr 2016 18:59:51 +0000
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Thu, 28 Apr 2016 09:58:59 -0300

perf record: Force enable --timestamp-filename when --switch-output is provided

Without this patch, the last output doesn't have timestamp appended if
--timestamp-filename is not explicitly provided. For example:

  # perf record -a --switch-output &
  [1] 11224
  # kill -s SIGUSR2 11224
  [ perf record: dump data: Woken up 1 times ]
  # [ perf record: Dump perf.data.2015122622372823 ]

  # fg
  perf record -a --switch-output
  ^C[ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.027 MB perf.data (540 samples) ]

  # ls -l
  total 836
  -rw------- 1 root root  33256 Dec 26 22:37 perf.data   <---- *Odd*
  -rw------- 1 root root 817156 Dec 26 22:37 perf.data.2015122622372823

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Tested-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Zefan Li <lizefan@xxxxxxxxxx>
Cc: pi3orama@xxxxxxx
Link: http://lkml.kernel.org/r/1461178794-40467-5-git-send-email-wangnan0@xxxxxxxxxx
Signed-off-by: He Kuang <hekuang@xxxxxxxxxx>
[ Updated man page, that also got an entry for --timestamp-filename ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/Documentation/perf-record.txt | 5 +++++
 tools/perf/builtin-record.c              | 3 +++
 2 files changed, 8 insertions(+)

diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index a77a431..79a8a14 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -347,6 +347,9 @@ Configure all used events to run in kernel space.
 --all-user::
 Configure all used events to run in user space.
 
+--timestamp-filename
+Append timestamp to output file name.
+
 --switch-output::
 Generate multiple perf.data files, timestamp prefixed, switching to a new one
 when receiving a SIGUSR2.
@@ -355,6 +358,8 @@ A possible use case is to, given an external event, slice the perf.data file
 that gets then processed, possibly via a perf script, to decide if that
 particular perf.data snapshot should be kept or not.
 
+Implies --timestamp-filename.
+
 SEE ALSO
 --------
 linkperf:perf-stat[1], linkperf:perf-list[1]
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 8ebe953..80b805b 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -1351,6 +1351,9 @@ int cmd_record(int argc, const char **argv, const char *prefix __maybe_unused)
 		return -EINVAL;
 	}
 
+	if (rec->switch_output)
+		rec->timestamp_filename = true;
+
 	if (!rec->itr) {
 		rec->itr = auxtrace_record__init(rec->evlist, &err);
 		if (err)