The --show-prio option is used to display the priority of task.

It is disabled by default, which is consistent with original behavior.

The display format is xxx (priority does not change during task running)
or xxx->yyy (priority changes during task running)

Testcase:

  # perf sched record nice -n 9 true
  [ perf record: Woken up 0 times to write data ]
  [ perf record: Captured and wrote 0.497 MB perf.data ]

  # perf sched timehist -h

   Usage: perf sched timehist [<options>]

      -C, --cpu <cpu>       list of cpus to profile
      -D, --dump-raw-trace  dump raw trace in ASCII
      -f, --force           don't complain, do it
      -g, --call-graph      Display call chains if present (default on)
      -I, --idle-hist       Show idle events only
      -i, --input <file>    input file name
      -k, --vmlinux <file>  vmlinux pathname
      -M, --migrations      Show migration events
      -n, --next            Show next task
      -p, --pid <pid[,pid...]>
                            analyze events only for given process id(s)
      -s, --summary         Show only syscall summary with statistics
      -S, --with-summary    Show all syscalls and summary with statistics
      -t, --tid <tid[,tid...]>
                            analyze events only for given thread id(s)
      -V, --cpu-visual      Add CPU visual
      -v, --verbose         be more verbose (show symbol address, etc)
      -w, --wakeups         Show wakeup events
          --kallsyms <file>
                            kallsyms pathname
          --max-stack <n>   Maximum number of functions to display backtrace.
          --show-prio       Show task priority
          --state           Show task state when sched-out
          --symfs <directory>
                            Look for files with symbols relative to this directory
          --time <str>      Time span for analysis (start,stop)

  # perf sched timehist
  Samples of sched_switch event do not have callchains.
             time    cpu  task name                       wait time  sch delay   run time
                          [tid/pid]                          (msec)     (msec)     (msec)
  --------------- ------  ------------------------------  ---------  ---------  ---------
     23952.006537 [0000]  perf[534]                           0.000      0.000      0.000
     23952.006593 [0000]  migration/0[19]                     0.000      0.014      0.056
     23952.006899 [0001]  perf[534]                           0.000      0.000      0.000
     23952.006947 [0001]  migration/1[22]                     0.000      0.015      0.047
     23952.007138 [0002]  perf[534]                           0.000      0.000      0.000
  <SNIP>

  # perf sched timehist --show-prio
  Samples of sched_switch event do not have callchains.
             time    cpu  task name                       prio      wait time  sch delay   run time
                          [tid/pid]                                    (msec)     (msec)     (msec)
  --------------- ------  ------------------------------  --------  ---------  ---------  ---------
     23952.006537 [0000]  perf[534]                       120           0.000      0.000      0.000
     23952.006593 [0000]  migration/0[19]                 0             0.000      0.014      0.056
     23952.006899 [0001]  perf[534]                       120           0.000      0.000      0.000
  <SNIP>
     23952.034843 [0003]  nice[535]                       120->129      0.189      0.024     23.314
  <SNIP>
     23952.053838 [0005]  rcu_preempt[16]                 120           3.993      0.000      0.023
     23952.053990 [0005]  <idle>                          120           0.023      0.023      0.152
     23952.054137 [0006]  <idle>                          120           1.427      1.427     17.855
     23952.054278 [0007]  <idle>                          120           0.506      0.506      1.650
Signed-off-by: Yang Jihong <yangjihong@bytedance.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240819033016.2427235-2-yangjihong@bytedance.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>