perf ftrace latency: Introduce --min-latency to narrow down into a latency range

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>