linux-kernel - Re: [PATCH 14/19] perf ftrace: add option -P/--no-pager to disable pager

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Date:   Sat, 6 Jun 2020 22:40:31 +0800
From:   Changbin Du <changbin.du@...il.com>
To:     Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
Cc:     Changbin Du <changbin.du@...il.com>, Jiri Olsa <jolsa@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 14/19] perf ftrace: add option -P/--no-pager to disable
 pager

On Wed, May 20, 2020 at 06:09:14PM -0300, Arnaldo Carvalho de Melo wrote:
> Em Sun, May 10, 2020 at 11:06:23PM +0800, Changbin Du escreveu:
> > Sometimes we want perf displays trace immediately. So this adds an option
> > '-P/--no-pager' to disable pager if needed.
> 
> 
> Try:
> 
> perf record sleep 5
> perf script
> 
> Then:
> 
> perf --no-pager script
> 
> I.e. its there already.
> 
> - Arnaldo
>
Yes, just tried this and it works:
perf --no-pager ftrace

So, the problem is that this option is not documented.
> > 
> > Signed-off-by: Changbin Du <changbin.du@...il.com>
> > ---
> >  tools/perf/builtin-ftrace.c | 17 ++++++++++++++---
> >  1 file changed, 14 insertions(+), 3 deletions(-)
> > 
> > diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
> > index a93fbdac6aa4..64c22f367ba2 100644
> > --- a/tools/perf/builtin-ftrace.c
> > +++ b/tools/perf/builtin-ftrace.c
> > @@ -48,6 +48,7 @@ struct perf_ftrace {
> >  	unsigned		tracing_thresh;
> >  	bool			trace_children;
> >  	unsigned		buffer_size_kb;
> > +	bool			no_pager;
> >  };
> >  
> >  struct filter_entry {
> > @@ -56,6 +57,7 @@ struct filter_entry {
> >  };
> >  
> >  static volatile int workload_exec_errno;
> > +static bool interrupted;
> >  static bool done;
> >  
> >  static void sig_handler(int sig __maybe_unused)
> > @@ -63,6 +65,12 @@ static void sig_handler(int sig __maybe_unused)
> >  	done = true;
> >  }
> >  
> > +static void sig_handler_int(int sig __maybe_unused)
> > +{
> > +	sig_handler(sig);
> > +	interrupted = 1;
> > +}
> > +
> >  /*
> >   * perf_evlist__prepare_workload will send a SIGUSR1 if the fork fails, since
> >   * we asked by setting its exec_error to the function below,
> > @@ -492,7 +500,7 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
> >  		return -1;
> >  	}
> >  
> > -	signal(SIGINT, sig_handler);
> > +	signal(SIGINT, sig_handler_int);
> >  	signal(SIGUSR1, sig_handler);
> >  	signal(SIGCHLD, sig_handler);
> >  	signal(SIGPIPE, sig_handler);
> > @@ -585,7 +593,8 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
> >  		goto out_reset;
> >  	}
> >  
> > -	setup_pager();
> > +	if (!ftrace->no_pager)
> > +		setup_pager();
> >  
> >  	trace_file = get_tracing_file("trace_pipe");
> >  	if (!trace_file) {
> > @@ -636,7 +645,7 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
> >  	}
> >  
> >  	/* read remaining buffer contents */
> > -	while (true) {
> > +	while (true && !interrupted) {
> >  		int n = read(trace_fd, buf, sizeof(buf));
> >  		if (n <= 0)
> >  			break;
> > @@ -731,6 +740,8 @@ int cmd_ftrace(int argc, const char **argv)
> >  		    "Trace children processes"),
> >  	OPT_UINTEGER('b', "buffer-size", &ftrace.buffer_size_kb,
> >  		     "size of per cpu buffer in kb"),
> > +	OPT_BOOLEAN('P', "no-pager", &ftrace.no_pager,
> > +		    "Do not use pager"),
> >  	OPT_END()
> >  	};
> >  
> > -- 
> > 2.25.1
> > 
> 
> -- 
> 
> - Arnaldo

-- 
Cheers,
Changbin Du