[PATCH 0/2] perf tools: Add --header/--header-only options

[PATCH 0/2] perf tools: Add --header/--header-only options

[Jiri Olsa]

Currently the perf.data header is always displayed for stdio
output, which is no always useful.

Disabling header information by default and adding following
options to control header output:
  --header      - display header information (old default)
  --header-only - display header information only w/o further
                  processing.

thanks,
jirka


Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: David Ahern <dsahern@gmail.com>
---
 tools/perf/Documentation/perf-report.txt |  6 ++++++
 tools/perf/Documentation/perf-script.txt |  6 ++++++
 tools/perf/builtin-report.c              | 19 ++++++++++++++++---
 tools/perf/builtin-script.c              | 13 ++++++++++---
 4 files changed, 38 insertions(+), 6 deletions(-)

[PATCH 1/2] perf report: Add --header/--header-only options

[Jiri Olsa]

Currently the perf.data header is always displayed for stdio
output, which is no always useful.

Disabling header information by default and adding following
options to control header output:
  --header      - display header information (old default)
  --header-only - display header information only w/o further
                  processing, forces stdio output

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: David Ahern <dsahern@gmail.com>
---
 tools/perf/Documentation/perf-report.txt |  6 ++++++
 tools/perf/builtin-report.c              | 19 ++++++++++++++++---
 2 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/tools/perf/Documentation/perf-report.txt b/tools/perf/Documentation/perf-report.txt
index 10a2798..e41cbfb 100644
--- a/tools/perf/Documentation/perf-report.txt
+++ b/tools/perf/Documentation/perf-report.txt
@@ -237,6 +237,12 @@ OPTIONS
 	Do not show entries which have an overhead under that percent.
 	(Default: 0).
 
+--header
+	Show perf.data header.
+
+--header-only
+	Show only perf.data header (forces --stdio).
+
 SEE ALSO
 --------
 linkperf:perf-stat[1], linkperf:perf-annotate[1]
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 8cf8e66..242fd6f 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -49,6 +49,8 @@ struct perf_report {
 	bool			show_threads;
 	bool			inverted_callchain;
 	bool			mem_mode;
+	bool			header;
+	bool			header_only;
 	int			max_stack;
 	struct perf_read_values	show_threads_values;
 	const char		*pretty_printing_style;
@@ -514,9 +516,6 @@ static int __cmd_report(struct perf_report *rep)
 			return ret;
 	}
 
-	if (use_browser <= 0)
-		perf_session__fprintf_info(session, stdout, rep->show_full_info);
-
 	if (rep->show_threads)
 		perf_read_values_init(&rep->show_threads_values);
 
@@ -820,6 +819,9 @@ int cmd_report(int argc, const char **argv, const char *prefix __maybe_unused)
 	OPT_BOOLEAN(0, "gtk", &report.use_gtk, "Use the GTK2 interface"),
 	OPT_BOOLEAN(0, "stdio", &report.use_stdio,
 		    "Use the stdio interface"),
+	OPT_BOOLEAN(0, "header", &report.header, "Show data header."),
+	OPT_BOOLEAN(0, "header-only", &report.header_only,
+		    "Show only data header."),
 	OPT_STRING('s', "sort", &sort_order, "key[,key2...]",
 		   "sort by key(s): pid, comm, dso, symbol, parent, cpu, srcline,"
 		   " dso_to, dso_from, symbol_to, symbol_from, mispredict,"
@@ -963,6 +965,10 @@ repeat:
 			goto error;
 	}
 
+	/* Force tty output for header output. */
+	if (report.header || report.header_only)
+		use_browser = 0;
+
 	if (strcmp(input_name, "-") != 0)
 		setup_browser(true);
 	else {
@@ -970,6 +976,13 @@ repeat:
 		perf_hpp__init();
 	}
 
+	if (report.header || report.header_only) {
+		perf_session__fprintf_info(session, stdout,
+					   report.show_full_info);
+		if (report.header_only)
+			return 0;
+	}
+
 	/*
 	 * Only in the TUI browser we are doing integrated annotation,
 	 * so don't allocate extra space that won't be used in the stdio
-- 
1.8.3.1

Re: [PATCH 1/2] perf report: Add --header/--header-only options

[Namhyung Kim]

On Mon,  9 Dec 2013 11:02:49 +0100, Jiri Olsa wrote:
> Currently the perf.data header is always displayed for stdio
> output, which is no always useful.
>
> Disabling header information by default and adding following
> options to control header output:
>   --header      - display header information (old default)
>   --header-only - display header information only w/o further
>                   processing, forces stdio output
>
[SNIP]
> +--header
> +	Show perf.data header.

This explanation looks too terse.  How about this?

	Show header information in the perf.data file.  This includes
        various information like hostname, os and perf version, cpu/mem
        info, perf command line, event list and so on.  Currently only
        --stdio output supports this feature.

Thanks,
Namhyung

> +
> +--header-only
> +	Show only perf.data header (forces --stdio).
> +
>  SEE ALSO
>  --------
>  linkperf:perf-stat[1], linkperf:perf-annotate[1]

Re: [PATCH 1/2] perf report: Add --header/--header-only options

[Jiri Olsa]

On Tue, Dec 10, 2013 at 09:12:10AM +0900, Namhyung Kim wrote:
> On Mon,  9 Dec 2013 11:02:49 +0100, Jiri Olsa wrote:
> > Currently the perf.data header is always displayed for stdio
> > output, which is no always useful.
> >
> > Disabling header information by default and adding following
> > options to control header output:
> >   --header      - display header information (old default)
> >   --header-only - display header information only w/o further
> >                   processing, forces stdio output
> >
> [SNIP]
> > +--header
> > +	Show perf.data header.
> 
> This explanation looks too terse.  How about this?
> 
> 	Show header information in the perf.data file.  This includes
>         various information like hostname, os and perf version, cpu/mem
>         info, perf command line, event list and so on.  Currently only
>         --stdio output supports this feature.

sounds good, I will use it

thanks,
jirka

[tip:perf/core] perf report: Add --header/--header-only options

[tip-bot for Jiri Olsa]

Commit-ID:  5cfe2c82f3eb6876cf4b55e99decea0bd015d6b8
Gitweb:     http://git.kernel.org/tip/5cfe2c82f3eb6876cf4b55e99decea0bd015d6b8
Author:     Jiri Olsa <jolsa@redhat.com>
AuthorDate: Mon, 9 Dec 2013 11:02:49 +0100
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Tue, 10 Dec 2013 16:49:02 -0300

perf report: Add --header/--header-only options

Currently the perf.data header is always displayed for stdio output,
which is no always useful.

Disabling header information by default and adding following options to
control header output:

  --header      - display header information (old default)
  --header-only - display header information only w/o further
                  processing, forces stdio output

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: David Ahern <dsahern@gmail.com>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1386583370-1699-2-git-send-email-jolsa@redhat.com
[ Added single line explaining talking about the new --header* options,
  to address David Ahern comment; better man page entry for the new options,
  from Namhyung Kim ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/Documentation/perf-report.txt |  9 +++++++++
 tools/perf/builtin-report.c              | 22 +++++++++++++++++++---
 2 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/tools/perf/Documentation/perf-report.txt b/tools/perf/Documentation/perf-report.txt
index 10a2798..8eab8a4 100644
--- a/tools/perf/Documentation/perf-report.txt
+++ b/tools/perf/Documentation/perf-report.txt
@@ -237,6 +237,15 @@ OPTIONS
 	Do not show entries which have an overhead under that percent.
 	(Default: 0).
 
+--header::
+	Show header information in the perf.data file.  This includes
+	various information like hostname, OS and perf version, cpu/mem
+	info, perf command line, event list and so on.  Currently only
+	--stdio output supports this feature.
+
+--header-only::
+	Show only perf.data header (forces --stdio).
+
 SEE ALSO
 --------
 linkperf:perf-stat[1], linkperf:perf-annotate[1]
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 8cf8e66..3a14dbe 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -49,6 +49,8 @@ struct perf_report {
 	bool			show_threads;
 	bool			inverted_callchain;
 	bool			mem_mode;
+	bool			header;
+	bool			header_only;
 	int			max_stack;
 	struct perf_read_values	show_threads_values;
 	const char		*pretty_printing_style;
@@ -514,9 +516,6 @@ static int __cmd_report(struct perf_report *rep)
 			return ret;
 	}
 
-	if (use_browser <= 0)
-		perf_session__fprintf_info(session, stdout, rep->show_full_info);
-
 	if (rep->show_threads)
 		perf_read_values_init(&rep->show_threads_values);
 
@@ -820,6 +819,9 @@ int cmd_report(int argc, const char **argv, const char *prefix __maybe_unused)
 	OPT_BOOLEAN(0, "gtk", &report.use_gtk, "Use the GTK2 interface"),
 	OPT_BOOLEAN(0, "stdio", &report.use_stdio,
 		    "Use the stdio interface"),
+	OPT_BOOLEAN(0, "header", &report.header, "Show data header."),
+	OPT_BOOLEAN(0, "header-only", &report.header_only,
+		    "Show only data header."),
 	OPT_STRING('s', "sort", &sort_order, "key[,key2...]",
 		   "sort by key(s): pid, comm, dso, symbol, parent, cpu, srcline,"
 		   " dso_to, dso_from, symbol_to, symbol_from, mispredict,"
@@ -963,6 +965,10 @@ repeat:
 			goto error;
 	}
 
+	/* Force tty output for header output. */
+	if (report.header || report.header_only)
+		use_browser = 0;
+
 	if (strcmp(input_name, "-") != 0)
 		setup_browser(true);
 	else {
@@ -970,6 +976,16 @@ repeat:
 		perf_hpp__init();
 	}
 
+	if (report.header || report.header_only) {
+		perf_session__fprintf_info(session, stdout,
+					   report.show_full_info);
+		if (report.header_only)
+			return 0;
+	} else if (use_browser == 0) {
+		fputs("# To display the perf.data header info, please use --header/--header-only options.\n#\n",
+		      stdout);
+	}
+
 	/*
 	 * Only in the TUI browser we are doing integrated annotation,
 	 * so don't allocate extra space that won't be used in the stdio

[PATCH 2/2] perf script: Add --header/--header-only options

[Jiri Olsa]

Currently the perf.data header is always displayed for stdio
output, which is no always useful.

Disabling header information by default and adding following
options to control header output:
  --header      - display header information
  --header-only - display header information only w/o further
                  processing

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: David Ahern <dsahern@gmail.com>
---
 tools/perf/Documentation/perf-script.txt |  6 ++++++
 tools/perf/builtin-script.c              | 13 ++++++++++---
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/tools/perf/Documentation/perf-script.txt b/tools/perf/Documentation/perf-script.txt
index cfdbb1e..ab3ce09 100644
--- a/tools/perf/Documentation/perf-script.txt
+++ b/tools/perf/Documentation/perf-script.txt
@@ -209,6 +209,12 @@ OPTIONS
 --show-mmap-events
 	Display mmap related events (e.g. MMAP, MMAP2).
 
+--header
+	Show perf.data header.
+
+--header-only
+	Show only perf.data header.
+
 SEE ALSO
 --------
 linkperf:perf-record[1], linkperf:perf-script-perl[1],
diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index 4484886..495b3b8 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -1484,6 +1484,8 @@ static int have_cmd(int argc, const char **argv)
 int cmd_script(int argc, const char **argv, const char *prefix __maybe_unused)
 {
 	bool show_full_info = false;
+	bool header = false;
+	bool header_only = false;
 	char *rec_script_path = NULL;
 	char *rep_script_path = NULL;
 	struct perf_session *session;
@@ -1522,6 +1524,8 @@ int cmd_script(int argc, const char **argv, const char *prefix __maybe_unused)
 	OPT_STRING('i', "input", &input_name, "file", "input file name"),
 	OPT_BOOLEAN('d', "debug-mode", &debug_mode,
 		   "do various checks like samples ordering and lost events"),
+	OPT_BOOLEAN(0, "header", &header, "Show data header."),
+	OPT_BOOLEAN(0, "header-only", &header_only, "Show only data header."),
 	OPT_STRING('k', "vmlinux", &symbol_conf.vmlinux_name,
 		   "file", "vmlinux pathname"),
 	OPT_STRING(0, "kallsyms", &symbol_conf.kallsyms_name,
@@ -1738,6 +1742,12 @@ int cmd_script(int argc, const char **argv, const char *prefix __maybe_unused)
 	if (session == NULL)
 		return -ENOMEM;
 
+	if (header || header_only) {
+		perf_session__fprintf_info(session, stdout, show_full_info);
+		if (header_only)
+			return 0;
+	}
+
 	script.session = session;
 
 	if (cpu_list) {
@@ -1745,9 +1755,6 @@ int cmd_script(int argc, const char **argv, const char *prefix __maybe_unused)
 			return -1;
 	}
 
-	if (!script_name && !generate_script_lang)
-		perf_session__fprintf_info(session, stdout, show_full_info);
-
 	if (!no_callchain)
 		symbol_conf.use_callchain = true;
 	else
-- 
1.8.3.1

[tip:perf/core] perf script: Add --header/--header-only options

[tip-bot for Jiri Olsa]

Commit-ID:  e90debddf8f26094cd90162b9af2a8ed37ed57cb
Gitweb:     http://git.kernel.org/tip/e90debddf8f26094cd90162b9af2a8ed37ed57cb
Author:     Jiri Olsa <jolsa@redhat.com>
AuthorDate: Mon, 9 Dec 2013 11:02:50 +0100
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Tue, 10 Dec 2013 16:51:07 -0300

perf script: Add --header/--header-only options

Currently the perf.data header is always displayed for stdio output,
which is no always useful.

Disabling header information by default and adding following options to
control header output:

  --header      - display header information
  --header-only - display header information only w/o further
                  processing

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/n/tip-0ehaawv5xc83w6ag03c5hi10@git.kernel.org
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1386583370-1699-3-git-send-email-jolsa@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/Documentation/perf-script.txt |  6 ++++++
 tools/perf/builtin-script.c              | 13 ++++++++++---
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/tools/perf/Documentation/perf-script.txt b/tools/perf/Documentation/perf-script.txt
index c2a5071..05f9a0a 100644
--- a/tools/perf/Documentation/perf-script.txt
+++ b/tools/perf/Documentation/perf-script.txt
@@ -209,6 +209,12 @@ OPTIONS
 --show-mmap-events
 	Display mmap related events (e.g. MMAP, MMAP2).
 
+--header
+	Show perf.data header.
+
+--header-only
+	Show only perf.data header.
+
 SEE ALSO
 --------
 linkperf:perf-record[1], linkperf:perf-script-perl[1],
diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index 7a571fb..f8ab125 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -1494,6 +1494,8 @@ static int have_cmd(int argc, const char **argv)
 int cmd_script(int argc, const char **argv, const char *prefix __maybe_unused)
 {
 	bool show_full_info = false;
+	bool header = false;
+	bool header_only = false;
 	char *rec_script_path = NULL;
 	char *rep_script_path = NULL;
 	struct perf_session *session;
@@ -1532,6 +1534,8 @@ int cmd_script(int argc, const char **argv, const char *prefix __maybe_unused)
 	OPT_STRING('i', "input", &input_name, "file", "input file name"),
 	OPT_BOOLEAN('d', "debug-mode", &debug_mode,
 		   "do various checks like samples ordering and lost events"),
+	OPT_BOOLEAN(0, "header", &header, "Show data header."),
+	OPT_BOOLEAN(0, "header-only", &header_only, "Show only data header."),
 	OPT_STRING('k', "vmlinux", &symbol_conf.vmlinux_name,
 		   "file", "vmlinux pathname"),
 	OPT_STRING(0, "kallsyms", &symbol_conf.kallsyms_name,
@@ -1748,6 +1752,12 @@ int cmd_script(int argc, const char **argv, const char *prefix __maybe_unused)
 	if (session == NULL)
 		return -ENOMEM;
 
+	if (header || header_only) {
+		perf_session__fprintf_info(session, stdout, show_full_info);
+		if (header_only)
+			return 0;
+	}
+
 	script.session = session;
 
 	if (cpu_list) {
@@ -1755,9 +1765,6 @@ int cmd_script(int argc, const char **argv, const char *prefix __maybe_unused)
 			return -1;
 	}
 
-	if (!script_name && !generate_script_lang)
-		perf_session__fprintf_info(session, stdout, show_full_info);
-
 	if (!no_callchain)
 		symbol_conf.use_callchain = true;
 	else

Re: [PATCH 0/2] perf tools: Add --header/--header-only options

[David Ahern]

[Added Stephane given that he added the header output]

On 12/9/13, 3:02 AM, Jiri Olsa wrote:
> Currently the perf.data header is always displayed for stdio
> output, which is no always useful.
>
> Disabling header information by default and adding following
> options to control header output:
>    --header      - display header information (old default)
>    --header-only - display header information only w/o further
>                    processing.
>
> thanks,
> jirka
>
>
> Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Ingo Molnar <mingo@elte.hu>
> Cc: Namhyung Kim <namhyung@kernel.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
> Cc: David Ahern <dsahern@gmail.com>
> ---
>   tools/perf/Documentation/perf-report.txt |  6 ++++++
>   tools/perf/Documentation/perf-script.txt |  6 ++++++
>   tools/perf/builtin-report.c              | 19 ++++++++++++++++---
>   tools/perf/builtin-script.c              | 13 ++++++++++---
>   4 files changed, 38 insertions(+), 6 deletions(-)
>

I've been getting annoyed but that as well. Very useful on the first 
run; overhead after that.

Acked-by: David Ahern <dsahern@gmail.com>

Re: [PATCH 0/2] perf tools: Add --header/--header-only options

[Arnaldo Carvalho de Melo]

Em Mon, Dec 09, 2013 at 04:25:29PM -0700, David Ahern escreveu:
> [Added Stephane given that he added the header output]

Yeah, I added him to the CC list in the patch when I merged it, Ingo had
asked me to do this quite some time ago, I also usually did:

$ perf report | grep -v ^#

When looking for the first few entries in a profile.

I think that with Namhyung's improvement to the man page + the single
line stating that --header should be used to get the previous behavior
we are ok, no?
 
> On 12/9/13, 3:02 AM, Jiri Olsa wrote:
> >Currently the perf.data header is always displayed for stdio
> >output, which is no always useful.

> >Disabling header information by default and adding following
> >options to control header output:
> >   --header      - display header information (old default)
> >   --header-only - display header information only w/o further
> >                   processing.

> I've been getting annoyed but that as well. Very useful on the first
> run; overhead after that.

> Acked-by: David Ahern <dsahern@gmail.com>

I'll add this since I'll have to reprocess the last batch due to the
dso__delete problem.

- Arnaldo

Re: [PATCH 0/2] perf tools: Add --header/--header-only options

[Namhyung Kim]

Hi Jiri,

On Mon,  9 Dec 2013 11:02:48 +0100, Jiri Olsa wrote:
> Currently the perf.data header is always displayed for stdio
> output, which is no always useful.
>
> Disabling header information by default and adding following
> options to control header output:

Hmm.. I'm not sure it's OK to change the user-visible default behavior.
At least we can provide help message for old users?

Thanks,
Namhyung


>   --header      - display header information (old default)
>   --header-only - display header information only w/o further
>                   processing.
>
> thanks,
> jirka
>
>
> Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Ingo Molnar <mingo@elte.hu>
> Cc: Namhyung Kim <namhyung@kernel.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
> Cc: David Ahern <dsahern@gmail.com>
> ---
>  tools/perf/Documentation/perf-report.txt |  6 ++++++
>  tools/perf/Documentation/perf-script.txt |  6 ++++++
>  tools/perf/builtin-report.c              | 19 ++++++++++++++++---
>  tools/perf/builtin-script.c              | 13 ++++++++++---
>  4 files changed, 38 insertions(+), 6 deletions(-)

Re: [PATCH 0/2] perf tools: Add --header/--header-only options

[Jiri Olsa]

On Tue, Dec 10, 2013 at 09:06:53AM +0900, Namhyung Kim wrote:
> Hi Jiri,
> 
> On Mon,  9 Dec 2013 11:02:48 +0100, Jiri Olsa wrote:
> > Currently the perf.data header is always displayed for stdio
> > output, which is no always useful.
> >
> > Disabling header information by default and adding following
> > options to control header output:
> 
> Hmm.. I'm not sure it's OK to change the user-visible default behavior.
> At least we can provide help message for old users?

maybe we could display on the first line something like:
 
  $ perf report --stdio
  # To display data file header, please use --header/--header-only options.
  #
  # Samples: 12  of event 'cycles'
  # Event count (approx.): 3741156
  #
  # Overhead  Command      Shared Object                     Symbol
  # ........  .......  .................  .........................
  ...


jirka