linux-kernel - Re: [PATCH 13/19] perf ftrace: add option '-b/--buffer-size' to set per-cpu buffer size

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Date:   Sat, 6 Jun 2020 22:43:38 +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 13/19] perf ftrace: add option '-b/--buffer-size' to set
 per-cpu buffer size

On Wed, May 20, 2020 at 06:08:14PM -0300, Arnaldo Carvalho de Melo wrote:
> Em Sun, May 10, 2020 at 11:06:22PM +0800, Changbin Du escreveu:
> > This adds an option '-b/--buffer-size' to allow us set the size of per-cpu
> > tracing buffer.
> 
> -m
>
sure.

> > Signed-off-by: Changbin Du <changbin.du@...il.com>
> > ---
> >  tools/perf/builtin-ftrace.c | 45 ++++++++++++++++++++++++++++---------
> >  1 file changed, 35 insertions(+), 10 deletions(-)
> > 
> > diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
> > index 8fd95c109fe8..a93fbdac6aa4 100644
> > --- a/tools/perf/builtin-ftrace.c
> > +++ b/tools/perf/builtin-ftrace.c
> > @@ -47,6 +47,7 @@ struct perf_ftrace {
> >  	bool			long_info;
> >  	unsigned		tracing_thresh;
> >  	bool			trace_children;
> > +	unsigned		buffer_size_kb;
> >  };
> >  
> >  struct filter_entry {
> > @@ -187,6 +188,17 @@ static int read_tracing_file_to_stdout(const char *name)
> >  	return ret;
> >  }
> >  
> > +static int write_tracing_file_int(const char *name, int value)
> > +{
> > +	char buf[16];
> > +
> > +	snprintf(buf, sizeof(buf), "%d", value);
> > +	if (write_tracing_file(name, buf) < 0)
> > +		return -1;
> > +
> > +	return 0;
> > +}
> > +
> >  static int reset_tracing_cpu(void);
> >  static void reset_tracing_filters(void);
> >  
> > @@ -360,8 +372,6 @@ static void reset_tracing_filters(void)
> >  
> >  static int set_tracing_depth(struct perf_ftrace *ftrace)
> >  {
> > -	char buf[16];
> > -
> >  	if (ftrace->graph_depth == 0)
> >  		return 0;
> >  
> > @@ -370,9 +380,7 @@ static int set_tracing_depth(struct perf_ftrace *ftrace)
> >  		return -1;
> >  	}
> >  
> > -	snprintf(buf, sizeof(buf), "%d", ftrace->graph_depth);
> > -
> > -	if (write_tracing_file("max_graph_depth", buf) < 0)
> > +	if (write_tracing_file_int("max_graph_depth", ftrace->graph_depth) < 0)
> >  		return -1;
> >  
> >  	return 0;
> > @@ -419,14 +427,10 @@ static int set_tracing_long_info(struct perf_ftrace *ftrace)
> >  
> >  static int set_tracing_thresh(struct perf_ftrace *ftrace)
> >  {
> > -	char buf[16];
> > -
> >  	if (ftrace->tracing_thresh == 0)
> >  		return 0;
> >  
> > -	snprintf(buf, sizeof(buf), "%d", ftrace->tracing_thresh);
> > -
> > -	if (write_tracing_file("tracing_thresh", buf) < 0)
> > +	if (write_tracing_file_int("tracing_thresh", ftrace->tracing_thresh) < 0)
> >  		return -1;
> >  
> >  	return 0;
> > @@ -454,6 +458,20 @@ static int set_tracing_trace_children(struct perf_ftrace *ftrace)
> >  	return 0;
> >  }
> >  
> > +static int set_tracing_buffer_size_kb(struct perf_ftrace *ftrace)
> > +{
> > +	int ret;
> > +
> > +	if (ftrace->buffer_size_kb == 0)
> > +		return 0;
> > +
> > +	ret = write_tracing_file_int("buffer_size_kb", ftrace->buffer_size_kb);
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	return 0;
> > +}
> > +
> >  static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
> >  {
> >  	char *trace_file;
> > @@ -557,6 +575,11 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
> >  		goto out_reset;
> >  	}
> >  
> > +	if (set_tracing_buffer_size_kb(ftrace) < 0) {
> > +		pr_err("failed to set tracing per-cpu buffer size\n");
> > +		goto out_reset;
> > +	}
> > +
> >  	if (write_tracing_file("current_tracer", ftrace->tracer) < 0) {
> >  		pr_err("failed to set current_tracer to %s\n", ftrace->tracer);
> >  		goto out_reset;
> > @@ -706,6 +729,8 @@ int cmd_ftrace(int argc, const char **argv)
> >  		     "Only show functions of which the duration is greater than <n>µs"),
> >  	OPT_BOOLEAN(0, "trace-children", &ftrace.trace_children,
> >  		    "Trace children processes"),
> > +	OPT_UINTEGER('b', "buffer-size", &ftrace.buffer_size_kb,
> > +		     "size of per cpu buffer in kb"),
> >  	OPT_END()
> >  	};
> >  
> > -- 
> > 2.25.1
> > 
> 
> -- 
> 
> - Arnaldo

-- 
Cheers,
Changbin Du