linux-kernel - [PATCH 2/3] perf record: Check conflict between '--timestamp-filename' option and pipe mode before recording

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Date: Fri, 19 Jan 2024 04:03:03 +0000
From: Yang Jihong <yangjihong1@...wei.com>
To: <peterz@...radead.org>, <mingo@...hat.com>, <acme@...nel.org>,
	<namhyung@...nel.org>, <mark.rutland@....com>,
	<alexander.shishkin@...ux.intel.com>, <jolsa@...nel.org>,
	<irogers@...gle.com>, <adrian.hunter@...el.com>,
	<linux-perf-users@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC: <yangjihong1@...wei.com>
Subject: [PATCH 2/3] perf record: Check conflict between '--timestamp-filename' option and pipe mode before recording

In pipe mode, no need to switch perf data output, therefore,
'--timestamp-filename' option should not take effect.
Check the conflict before recording and output WARNING.
In this case, the check pipe mode in perf_data__switch() can be removed.

Before:

  # perf record --timestamp-filename -o- perf test -w noploop | perf report -i- --percent-limit=1
  # To display the perf.data header info, please use --header/--header-only options.
  #
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Dump -.2024011812110182 ]
  #
  # Total Lost Samples: 0
  #
  # Samples: 4K of event 'cycles:P'
  # Event count (approx.): 2176784359
  #
  # Overhead  Command  Shared Object         Symbol
  # ........  .......  ....................  ......................................
  #
      97.83%  perf     perf                  [.] noploop

  #
  # (Tip: Print event counts in CSV format with: perf stat -x,)
  #

After:

  # perf record --timestamp-filename -o- perf test -w noploop | perf report -i- --percent-limit=1
  WARNING: --timestamp-filename option is not available in pipe mode.
  # To display the perf.data header info, please use --header/--header-only options.
  #
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.000 MB - ]
  #
  # Total Lost Samples: 0
  #
  # Samples: 4K of event 'cycles:P'
  # Event count (approx.): 2185575421
  #
  # Overhead  Command  Shared Object          Symbol
  # ........  .......  .....................  .............................................
  #
      97.75%  perf     perf                   [.] noploop

  #
  # (Tip: Profiling branch (mis)predictions with: perf record -b / perf report)
  #

Fixes: ecfd7a9c044e ("perf record: Add '--timestamp-filename' option to append timestamp to output file name")
Signed-off-by: Yang Jihong <yangjihong1@...wei.com>
---
 tools/perf/builtin-record.c | 5 +++++
 tools/perf/util/data.c      | 2 --
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index fb8d4067b76c..5e3ea5cf1429 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -2472,6 +2472,11 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
 	if (data->is_pipe && rec->evlist->core.nr_entries == 1)
 		rec->opts.sample_id = true;
 
+	if (rec->timestamp_filename && perf_data__is_pipe(data)) {
+		rec->timestamp_filename = false;
+		pr_warning("WARNING: --timestamp-filename option is not available in pipe mode.\n");
+	}
+
 	evlist__uniquify_name(rec->evlist);
 
 	/* Debug message used by test scripts */
diff --git a/tools/perf/util/data.c b/tools/perf/util/data.c
index c29d8a382b19..550675ce0b78 100644
--- a/tools/perf/util/data.c
+++ b/tools/perf/util/data.c
@@ -430,8 +430,6 @@ int perf_data__switch(struct perf_data *data,
 {
 	int ret;
 
-	if (check_pipe(data))
-		return -EINVAL;
 	if (perf_data__is_read(data))
 		return -EINVAL;
 
-- 
2.34.1