linux-kernel - Re: [PATCH 2/2] perf ftrace: Fix display for range of the first bucket

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Message-ID: <Z4Eqh5R1M5dElkYN@x1>
Date: Fri, 10 Jan 2025 11:11:19 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Namhyung Kim <namhyung@...nel.org>
Cc: Ian Rogers <irogers@...gle.com>, Kan Liang <kan.liang@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>, LKML <linux-kernel@...r.kernel.org>,
	linux-perf-users@...r.kernel.org,
	Gabriele Monaco <gmonaco@...hat.com>
Subject: Re: [PATCH 2/2] perf ftrace: Fix display for range of the first
 bucket

On Fri, Jan 10, 2025 at 11:08:48AM -0300, Arnaldo Carvalho de Melo wrote:
> On Wed, Jan 08, 2025 at 01:00:15PM -0800, Namhyung Kim wrote:
> > When min_latency is not given, it prints 0 - 0.  It should be 0 - 1.
> > 
> > Before:
> >   $ sudo ./perf ftrace latency -a -T do_futex sleep 1
> >   #   DURATION     |      COUNT | GRAPH                                          |
> >        0 -    0 us |        321 | ###########                                    |
> >   ...
> > 
> > After:
> >   $ sudo ./perf ftrace latency -a -T do_futex sleep 1
> >   #   DURATION     |      COUNT | GRAPH                                          |
> >        0 -    1 us |        699 | ############                                   |
> >   ...
> > 
> > Fixes: b875b6bf608589 ("perf ftrace latency: Introduce --min-latency to narrow down into a latency range")
> 
> I couldn't find the above cset in perf-tools not perf-tools-next nor in
> upstream, I fixed it up to:

It is just in perf-tools-next, so probably I did some rebase and that
explains this. Anyway, that should be stable now.

- Arnaldo
 
> Fixes: 08b875b6bf608589 ("perf ftrace latency: Introduce --min-latency to narrow down into a latency range")
> 
> Thanks,
> 
> - Arnaldo
> 
> > Cc: Gabriele Monaco <gmonaco@...hat.com>
> > Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> > ---
> >  tools/perf/builtin-ftrace.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
> > index 90cf2c9915a7e35b..cfd770ec72867d77 100644
> > --- a/tools/perf/builtin-ftrace.c
> > +++ b/tools/perf/builtin-ftrace.c
> > @@ -840,7 +840,7 @@ static void display_histogram(struct perf_ftrace *ftrace, int buckets[])
> >  	bar_len = buckets[0] * bar_total / total;
> >  
> >  	printf("  %4d - %4d %s | %10d | %.*s%*s |\n",
> > -	       0, min_latency, use_nsec ? "ns" : "us",
> > +	       0, min_latency ?: 1, use_nsec ? "ns" : "us",
> >  	       buckets[0], bar_len, bar, bar_total - bar_len, "");
> >  
> >  	for (i = 1; i < NUM_BUCKET - 1; i++) {
> > -- 
> > 2.47.1.613.gc27f4b7a9f-goog