Re: [PATCH v8 13/18] perf ftrace: add support for trace option tracing_thresh

[Changbin Du <changbin.du@gmail.com>]

On Fri, Aug 14, 2020 at 09:33:10AM -0300, Arnaldo Carvalho de Melo wrote:
> Em Sat, Aug 08, 2020 at 10:31:36AM +0800, Changbin Du escreveu:
> > This adds an option '--graph-opts thresh' to setup trace duration
> > threshold for funcgraph tracer.
> 
> Applied, please consider making --duration an alias for this, as this is
> also available in 'perf trace':
> 
> [root@quaco ~]# perf trace --duration 500 --max-events=5
>    369.860 gnome-shell/2084 poll(ufds: 0x559577983080, nfds: 21, timeout_msecs: 7194) = 1
>    493.654 pool-geoclue/386046 futex(uaddr: 0x56024843b610, op: WAIT|PRIVATE_FLAG, val: 1201, utime: 0x7f32bd7f9cc0) = -1 ETIMEDOUT (Connection timed out)
>     71.604 WebRTC_Worker/111634 futex(uaddr: 0x7fb4c364d608, op: WAIT_BITSET|PRIVATE_FLAG, val: 0, utime: 0x7fb4c364d410, val3: MATCH_ANY) = -1 ETIMEDOUT (Connection timed out)
>    601.645 pool-gsd-smart/2469 clock_nanosleep(which_clock: 0, flags: 0, rqtp: 0x7fb82cbd1cf0, rmtp: 0x7fb82cbd1d00) = 0
>    623.823 chromium-brows/92363 futex(uaddr: 0x7ffcfd064e38, op: WAIT_BITSET|PRIVATE_FLAG, val: 0, utime: 0x7ffcfd064c40, val3: MATCH_ANY) = -1 ETIMEDOUT (Connection timed out)
> [root@quaco ~]#
> 
>   $ perf trace -h duration
> 
>         --duration <float>
>                           show only events with duration > N.M ms
> 
>   $
> 
> This way one would be able to do:
> 
>   # perf trace --duration N.M
> 
> To see at syscall level, then add 'f':
> 
>   # perf ftrace --duration N.M
> 
> To see at kernel function level. Switching from one perf tool to another
> with such ease is the main objective here, I'd say :-)
>
Sure. Currently the unit for ftrace is 'ns'. I could change it to 'ms' at perf
level.

> - Arnaldo
>  
> > $ sudo ./perf ftrace -G '*' --graph-opts thresh=100
> >  3) ! 184.060 us  |    } /* schedule */
> >  3) ! 185.600 us  |  } /* exit_to_usermode_loop */
> >  2) ! 225.989 us  |    } /* schedule_idle */
> >  2) # 4140.051 us |  } /* do_idle */
> > 
> > Signed-off-by: Changbin Du <changbin.du@gmail.com>
> > ---
> >  tools/perf/Documentation/perf-ftrace.txt |  1 +
> >  tools/perf/builtin-ftrace.c              | 26 +++++++++++++++++++++++-
> >  2 files changed, 26 insertions(+), 1 deletion(-)
> > 
> > diff --git a/tools/perf/Documentation/perf-ftrace.txt b/tools/perf/Documentation/perf-ftrace.txt
> > index a2056aaf2ece..6fa927e5971b 100644
> > --- a/tools/perf/Documentation/perf-ftrace.txt
> > +++ b/tools/perf/Documentation/perf-ftrace.txt
> > @@ -107,6 +107,7 @@ OPTIONS
> >  	  nosleep-time - Measure on-CPU time only for function_graph tracer.
> >  	  noirqs       - Ignore functions that happen inside interrupt.
> >  	  verbose      - Show process names, PIDs, timestamps, etc.
> > +	  thresh=<n>   - Setup trace duration threshold in microseconds.
> >  
> >  SEE ALSO
> >  --------
> > diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
> > index 8ee5287bd84a..ca61f8b8bbf6 100644
> > --- a/tools/perf/builtin-ftrace.c
> > +++ b/tools/perf/builtin-ftrace.c
> > @@ -48,6 +48,7 @@ struct perf_ftrace {
> >  	int			graph_nosleep_time;
> >  	int			graph_noirqs;
> >  	int			graph_verbose;
> > +	int			graph_thresh;
> >  };
> >  
> >  struct filter_entry {
> > @@ -234,6 +235,9 @@ static int reset_tracing_files(struct perf_ftrace *ftrace __maybe_unused)
> >  	if (write_tracing_file("max_graph_depth", "0") < 0)
> >  		return -1;
> >  
> > +	if (write_tracing_file("tracing_thresh", "0") < 0)
> > +		return -1;
> > +
> >  	reset_tracing_filters();
> >  	reset_tracing_options(ftrace);
> >  	return 0;
> > @@ -446,6 +450,20 @@ static int set_tracing_funcgraph_verbose(struct perf_ftrace *ftrace)
> >  	return 0;
> >  }
> >  
> > +static int set_tracing_thresh(struct perf_ftrace *ftrace)
> > +{
> > +	int ret;
> > +
> > +	if (ftrace->graph_thresh == 0)
> > +		return 0;
> > +
> > +	ret = write_tracing_file_int("tracing_thresh", ftrace->graph_thresh);
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	return 0;
> > +}
> > +
> >  static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
> >  {
> >  	char *trace_file;
> > @@ -545,6 +563,11 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
> >  		goto out_reset;
> >  	}
> >  
> > +	if (set_tracing_thresh(ftrace) < 0) {
> > +		pr_err("failed to set tracing thresh\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;
> > @@ -727,6 +750,7 @@ static int parse_graph_tracer_opts(const struct option *opt,
> >  		{ .name = "nosleep-time",	.value_ptr = &ftrace->graph_nosleep_time },
> >  		{ .name = "noirqs",		.value_ptr = &ftrace->graph_noirqs },
> >  		{ .name = "verbose",		.value_ptr = &ftrace->graph_verbose },
> > +		{ .name = "thresh",		.value_ptr = &ftrace->graph_thresh },
> >  		{ .name = NULL, }
> >  	};
> >  
> > @@ -798,7 +822,7 @@ int cmd_ftrace(int argc, const char **argv)
> >  	OPT_INTEGER('D', "graph-depth", &ftrace.graph_depth,
> >  		    "Max depth for function graph tracer"),
> >  	OPT_CALLBACK(0, "graph-opts", &ftrace, "options",
> > -		     "graph tracer options, available options: nosleep-time,noirqs,verbose",
> > +		     "graph tracer options, available options: nosleep-time,noirqs,verbose,thresh=<n>",
> >  		     parse_graph_tracer_opts),
> >  	OPT_CALLBACK('m', "buffer-size", &ftrace.percpu_buffer_size, "size",
> >  		     "size of per cpu buffer", parse_buffer_size),
> > -- 
> > 2.25.1
> > 
> 
> -- 
> 
> - Arnaldo

-- 
Cheers,
Changbin Du