diff options
| author | Arnaldo Carvalho de Melo <acme@redhat.com> | 2024-11-12 21:12:13 +0300 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2024-12-10 21:16:27 +0300 |
| commit | 08b875b6bf6085894f5cc65e028ae76f371a805e (patch) | |
| tree | a286a58fc872e24cb69ca27cc331e943ad683a97 /tools/perf/util/bpf_ftrace.c | |
| parent | e8536dd47a98b5dbfac1dcdd2954b502bf656044 (diff) | |
| download | linux-08b875b6bf6085894f5cc65e028ae76f371a805e.tar.xz | |
perf ftrace latency: Introduce --min-latency to narrow down into a latency range
Things below and over will be in the first and last, outlier, buckets.
Without it:
# perf ftrace latency --use-nsec --use-bpf \
--bucket-range=200 \
-T switch_mm_irqs_off -a sleep 2
# DURATION | COUNT | GRAPH |
0 - 200 ns | 0 | |
200 - 400 ns | 44 | |
400 - 600 ns | 291 | # |
600 - 800 ns | 506 | ## |
800 - 1000 ns | 148 | |
1.00 - 1.20 us | 581 | ## |
1.20 - 1.40 us | 2199 | ########## |
1.40 - 1.60 us | 1048 | #### |
1.60 - 1.80 us | 1448 | ###### |
1.80 - 2.00 us | 1091 | ##### |
2.00 - 2.20 us | 517 | ## |
2.20 - 2.40 us | 318 | # |
2.40 - 2.60 us | 370 | # |
2.60 - 2.80 us | 271 | # |
2.80 - 3.00 us | 150 | |
3.00 - 3.20 us | 85 | |
3.20 - 3.40 us | 48 | |
3.40 - 3.60 us | 40 | |
3.60 - 3.80 us | 22 | |
3.80 - 4.00 us | 13 | |
4.00 - 4.20 us | 14 | |
4.20 - ... us | 626 | ## |
#
# perf ftrace latency --use-nsec --use-bpf \
--bucket-range=20 --min-latency=1200 \
-T switch_mm_irqs_off -a sleep 2
# DURATION | COUNT | GRAPH |
0 - 1200 ns | 1243 | ##### |
1.20 - 1.22 us | 141 | |
1.22 - 1.24 us | 202 | |
1.24 - 1.26 us | 209 | |
1.26 - 1.28 us | 219 | |
1.28 - 1.30 us | 208 | |
1.30 - 1.32 us | 245 | # |
1.32 - 1.34 us | 246 | # |
1.34 - 1.36 us | 224 | # |
1.36 - 1.38 us | 219 | |
1.38 - 1.40 us | 206 | |
1.40 - 1.42 us | 190 | |
1.42 - 1.44 us | 190 | |
1.44 - 1.46 us | 146 | |
1.46 - 1.48 us | 140 | |
1.48 - 1.50 us | 125 | |
1.50 - 1.52 us | 115 | |
1.52 - 1.54 us | 102 | |
1.54 - 1.56 us | 87 | |
1.56 - 1.58 us | 90 | |
1.58 - 1.60 us | 85 | |
1.60 - ... us | 5487 | ######################## |
#
Now we want focus on the latencies starting at 1.2us, with a finer
grained range of 20ns:
This is all on a live system, so statistically interesting, but not
narrowing down on the same numbers, so a 'perf ftrace latency record'
seems interesting to then use all on the same snapshot of latencies.
A --max-latency counterpart should come next, at first limiting the
max-latency to 20 * bucket-size, as we have a fixed buckets array with
20 + 2 entries (+ for the outliers) and thus would need to make it
larger for higher latencies.
We also may need a way to ask for not considering the out of range
values (first and last buckets) when drawing the buckets bars.
Co-developed-by: Gabriele Monaco <gmonaco@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20241112181214.1171244-4-acme@kernel.org
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/util/bpf_ftrace.c')
| -rw-r--r-- | tools/perf/util/bpf_ftrace.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/tools/perf/util/bpf_ftrace.c b/tools/perf/util/bpf_ftrace.c index b3cb68295e56..bc484e65fb8f 100644 --- a/tools/perf/util/bpf_ftrace.c +++ b/tools/perf/util/bpf_ftrace.c @@ -37,6 +37,7 @@ int perf_ftrace__latency_prepare_bpf(struct perf_ftrace *ftrace) } skel->rodata->bucket_range = ftrace->bucket_range; + skel->rodata->min_latency = ftrace->min_latency; /* don't need to set cpu filter for system-wide mode */ if (ftrace->target.cpu_list) { |