perf ftrace latency: Add --max-latency option

This patch adds a max-latency option as discussed, in case the number of
buckets is more than 22, we don't observe the setting (for now, let's
say).

By default or if 0 is passed, the value is automatically determined
based on the number of buckets, range and minimum, so that we fill all
available buffers (equivalent to the behaviour before this patch).

We now get something like this:

  # perf ftrace latency --bucket-range=20 \
			--min-latency 10 \
			--max-latency=100 \
			-T switch_mm_irqs_off -a sleep 2
  #   DURATION     |      COUNT | GRAPH             |
       0 -   10 us |       1731 | ################  |
      10 -   30 us |          1 |                   |
      30 -   50 us |          0 |                   |
      50 -   70 us |          0 |                   |
      70 -   90 us |          0 |                   |
      90 -  100 us |          0 |                   |
     100 -  ... us |          0 |                   |

Note the maximum is observed also if it doesn't cover completely a full
range (the second to last range is 10us long to let the last start at
100 sharp), this looks to me more sensible and eases the computations,
since we don't need to account for the range while filling the buckets.

Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
Tested-by: Arnaldo Carvalho de Melo <acme@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/20241112181214.1171244-5-acme@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

0 files changed, 0 insertions, 0 deletions