perf kwork: Implement perf kwork latency

Implements framework of perf kwork latency, which is used to report time
properties such as delay time and frequency.

Test cases:

  # perf kwork lat -h

   Usage: perf kwork latency [<options>]

      -C, --cpu <cpu>       list of cpus to profile
      -i, --input <file>    input file name
      -n, --name <name>     event name to profile
      -s, --sort <key[,key2...]>
                            sort by key(s): avg, max, count
          --time <str>      Time span for analysis (start,stop)

  # perf kwork lat -C 199
  Requested CPU 199 too large. Consider raising MAX_NR_CPUS
  Invalid cpu bitmap

  # perf kwork lat -i perf_no_exist.data
  failed to open perf_no_exist.data: No such file or directory

  # perf kwork lat -s avg1
    Error: Unknown --sort key: `avg1'

   Usage: perf kwork latency [<options>]

      -C, --cpu <cpu>       list of cpus to profile
      -i, --input <file>    input file name
      -n, --name <name>     event name to profile
      -s, --sort <key[,key2...]>
                            sort by key(s): avg, max, count
          --time <str>      Time span for analysis (start,stop)

  # perf kwork lat --time FFFF,
  Invalid time span

  # perf kwork lat

    Kwork Name                     | Cpu  | Avg delay     | Count    | Max delay     | Max delay start     | Max delay end       |
   --------------------------------------------------------------------------------------------------------------------------------
   --------------------------------------------------------------------------------------------------------------------------------
    INFO: 36.570% skipped events (31537 including 0 raise, 31537 entry, 0 exit)

Since there are no latency-enabled events, the output is empty.

Signed-off-by: Yang Jihong <yangjihong1@huawei.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Clarke <pc@us.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220709015033.38326-11-yangjihong1@huawei.com
[ Add {} for multiline if blocks ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 29 insertions, 0 deletions

diff --git a/tools/perf/Documentation/perf-kwork.txt b/tools/perf/Documentation/perf-kwork.txt
index b79b2c0d047e..069981457de1 100644
--- a/tools/perf/Documentation/perf-kwork.txt
+++ b/tools/perf/Documentation/perf-kwork.txt
@@ -19,9 +19,12 @@ There are several variants of 'perf kwork':
 
   'perf kwork report' to report the per kwork runtime.
 
+  'perf kwork latency' to report the per kwork latencies.
+
     Example usage:
         perf kwork record -- sleep 1
         perf kwork report
+        perf kwork latency
 
 OPTIONS
 -------
@@ -71,6 +74,32 @@ OPTIONS for 'perf kwork report'
 	stop time is not given (i.e, time string is 'x.y,') then analysis goes
 	to end of file.
 
+OPTIONS for 'perf kwork latency'
+----------------------------
+
+-C::
+--cpu::
+	Only show events for the given CPU(s) (comma separated list).
+
+-i::
+--input::
+	Input file name. (default: perf.data unless stdin is a fifo)
+
+-n::
+--name::
+	Only show events for the given name.
+
+-s::
+--sort::
+	Sort by key(s): avg, max, count
+
+--time::
+	Only analyze samples within given time window: <start>,<stop>. Times
+	have the format seconds.microseconds. If start is not given (i.e., time
+	string is ',x.y') then analysis starts at the beginning of the file. If
+	stop time is not given (i.e, time string is 'x.y,') then analysis goes
+	to end of file.
+
 SEE ALSO
 --------
 linkperf:perf-record[1]