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Message-ID: <20250207080446.77630-2-gmonaco@redhat.com>
Date: Fri, 7 Feb 2025 09:04:45 +0100
From: Gabriele Monaco <gmonaco@...hat.com>
To: linux-kernel@...r.kernel.org,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Namhyung Kim <namhyung@...nel.org>,
linux-perf-users@...r.kernel.org
Cc: Gabriele Monaco <gmonaco@...hat.com>
Subject: [PATCH 2/2] perf ftrace latency: allow to hide empty buckets
Especially while using several buckets, it isn't uncommon to have some
of them empty and reading the histogram may be a bit more complex:
# perf ftrace latency -a -T mutex_lock --bucket-range 5 --max-latency 200
# DURATION | COUNT | GRAPH |
0 - 5 us | 14816 | ###################################### |
5 - 10 us | 1228 | ### |
10 - 15 us | 438 | # |
15 - 20 us | 106 | |
20 - 25 us | 21 | |
25 - 30 us | 11 | |
30 - 35 us | 1 | |
35 - 40 us | 2 | |
40 - 45 us | 4 | |
45 - 50 us | 0 | |
50 - 55 us | 1 | |
55 - 60 us | 0 | |
60 - 65 us | 1 | |
65 - 70 us | 1 | |
70 - 75 us | 1 | |
75 - 80 us | 2 | |
80 - 85 us | 0 | |
85 - 90 us | 1 | |
90 - 95 us | 0 | |
95 - 100 us | 1 | |
100 - 105 us | 0 | |
105 - 110 us | 0 | |
110 - 115 us | 0 | |
115 - 120 us | 0 | |
120 - 125 us | 1 | |
125 - 130 us | 0 | |
130 - 135 us | 0 | |
135 - 140 us | 1 | |
140 - 145 us | 0 | |
145 - 150 us | 0 | |
150 - 155 us | 0 | |
155 - 160 us | 0 | |
160 - 165 us | 0 | |
165 - 170 us | 0 | |
170 - 175 us | 0 | |
175 - 180 us | 0 | |
180 - 185 us | 0 | |
185 - 190 us | 0 | |
190 - 195 us | 0 | |
195 - 200 us | 0 | |
200 - ... us | 2 | |
Allow the optional flag --hide-empty to remove buckets with no element
and produce a more compact graph. This feature could be misleading since
there is no clear indication for missing buckets, for this reason it's
disabled by default.
# perf ftrace latency -a -T mutex_lock --bucket-range 5 --max-latency --hide-empty 200
# DURATION | COUNT | GRAPH |
0 - 5 us | 14816 | ###################################### |
5 - 10 us | 1228 | ### |
10 - 15 us | 438 | # |
15 - 20 us | 106 | |
20 - 25 us | 21 | |
25 - 30 us | 11 | |
30 - 35 us | 1 | |
35 - 40 us | 2 | |
40 - 45 us | 4 | |
50 - 55 us | 1 | |
60 - 65 us | 1 | |
65 - 70 us | 1 | |
70 - 75 us | 1 | |
75 - 80 us | 2 | |
85 - 90 us | 1 | |
95 - 100 us | 1 | |
120 - 125 us | 1 | |
135 - 140 us | 1 | |
200 - ... us | 2 | |
Signed-off-by: Gabriele Monaco <gmonaco@...hat.com>
---
tools/perf/builtin-ftrace.c | 14 +++++++++++---
tools/perf/util/ftrace.h | 1 +
2 files changed, 12 insertions(+), 3 deletions(-)
diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
index 4f76094ea06d4..7caa18d5ffc38 100644
--- a/tools/perf/builtin-ftrace.c
+++ b/tools/perf/builtin-ftrace.c
@@ -841,14 +841,17 @@ 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 ?: 1, use_nsec ? "ns" : "us",
- buckets[0], bar_len, bar, bar_total - bar_len, "");
+ if (!ftrace->hide_empty || buckets[0])
+ printf(" %4d - %4d %s | %10d | %.*s%*s |\n",
+ 0, min_latency ?: 1, use_nsec ? "ns" : "us",
+ buckets[0], bar_len, bar, bar_total - bar_len, "");
for (i = 1; i < bucket_num - 1; i++) {
unsigned int start, stop;
const char *unit = use_nsec ? "ns" : "us";
+ if (ftrace->hide_empty && !buckets[i])
+ continue;
if (!ftrace->bucket_range) {
start = (1 << (i - 1));
stop = 1 << i;
@@ -884,6 +887,8 @@ static void display_histogram(struct perf_ftrace *ftrace, int buckets[])
}
bar_len = buckets[bucket_num - 1] * bar_total / total;
+ if (ftrace->hide_empty && !buckets[bucket_num - 1])
+ goto print_stats;
if (!ftrace->bucket_range) {
printf(" %4d - %-4s %s", 1, "...", use_nsec ? "ms" : "s ");
} else {
@@ -902,6 +907,7 @@ static void display_histogram(struct perf_ftrace *ftrace, int buckets[])
printf(" | %10d | %.*s%*s |\n", buckets[bucket_num - 1],
bar_len, bar, bar_total - bar_len, "");
+print_stats:
printf("\n# statistics (in %s)\n", ftrace->use_nsec ? "nsec" : "usec");
printf(" total time: %20.0f\n", latency_stats.mean * latency_stats.n);
printf(" avg time: %20.0f\n", latency_stats.mean);
@@ -1645,6 +1651,8 @@ int cmd_ftrace(int argc, const char **argv)
"Minimum latency (1st bucket). Works only with --bucket-range."),
OPT_UINTEGER(0, "max-latency", &ftrace.max_latency,
"Maximum latency (last bucket). Works only with --bucket-range."),
+ OPT_BOOLEAN(0, "hide-empty", &ftrace.hide_empty,
+ "Hide empty buckets in the histogram"),
OPT_PARENT(common_options),
};
const struct option profile_options[] = {
diff --git a/tools/perf/util/ftrace.h b/tools/perf/util/ftrace.h
index 395f97b203ead..a9bc47da83a56 100644
--- a/tools/perf/util/ftrace.h
+++ b/tools/perf/util/ftrace.h
@@ -25,6 +25,7 @@ struct perf_ftrace {
unsigned int min_latency;
unsigned int max_latency;
unsigned int bucket_num;
+ bool hide_empty;
int graph_depth;
int func_stack_trace;
int func_irq_info;
--
2.48.1
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