perf kwork: Add workqueue latency support

Implements workqueue latency function.

Test cases:

# perf kwork -k workqueue lat

Kwork Name | Cpu | Avg delay | Count | Max delay | Max delay start | Max delay end |
--------------------------------------------------------------------------------------------------------------------------------
(w)vmstat_update | 0001 | 5.004 ms | 1 | 5.004 ms | 44001.745646 s | 44001.750650 s |
(w)vmstat_update | 0006 | 1.773 ms | 1 | 1.773 ms | 44000.830840 s | 44000.832613 s |
(w)vmstat_shepherd | 0000 | 0.992 ms | 8 | 2.474 ms | 44007.717845 s | 44007.720318 s |
(w)vmstat_update | 0000 | 0.974 ms | 5 | 2.624 ms | 44004.785970 s | 44004.788594 s |
(w)e1000_watchdog | 0002 | 0.687 ms | 5 | 2.632 ms | 44005.009334 s | 44005.011966 s |
(w)vmstat_update | 0002 | 0.307 ms | 1 | 0.307 ms | 44004.817395 s | 44004.817702 s |
(w)vmstat_update | 0004 | 0.296 ms | 1 | 0.296 ms | 43997.913677 s | 43997.913973 s |
(w)mix_interrupt_randomness | 0000 | 0.283 ms | 285 | 3.724 ms | 44006.790889 s | 44006.794613 s |
(w)neigh_managed_work | 0001 | 0.271 ms | 1 | 0.271 ms | 43997.665542 s | 43997.665813 s |
(w)vmstat_update | 0005 | 0.261 ms | 1 | 0.261 ms | 44007.820542 s | 44007.820803 s |
(w)neigh_managed_work | 0004 | 0.220 ms | 1 | 0.220 ms | 44002.953287 s | 44002.953507 s |
(w)neigh_periodic_work | 0004 | 0.217 ms | 1 | 0.217 ms | 43999.929718 s | 43999.929935 s |
(w)mix_interrupt_randomness | 0002 | 0.199 ms | 5 | 0.310 ms | 44005.012316 s | 44005.012625 s |
(w)vmstat_update | 0003 | 0.199 ms | 4 | 0.307 ms | 44005.714391 s | 44005.714699 s |
(w)gc_worker | 0001 | 0.071 ms | 173 | 1.128 ms | 44002.062579 s | 44002.063707 s |
--------------------------------------------------------------------------------------------------------------------------------
INFO: 0.020% skipped events (17 including 10 raise, 7 entry, 0 exit)

Signed-off-by: Yang Jihong <[e-mail]>
Tested-by: Arnaldo Carvalho de Melo <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Paul Clarke <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/builtin-kwork.c

···
 };
 
 static struct kwork_class kwork_workqueue;
+static int process_workqueue_activate_work_event(struct perf_tool *tool,
+						 struct evsel *evsel,
+						 struct perf_sample *sample,
+						 struct machine *machine)
+{
+	struct perf_kwork *kwork = container_of(tool, struct perf_kwork, tool);
+
+	if (kwork->tp_handler->raise_event)
+		return kwork->tp_handler->raise_event(kwork, &kwork_workqueue,
+						    evsel, sample, machine);
+
+	return 0;
+}
+
 static int process_workqueue_execute_start_event(struct perf_tool *tool,
 						 struct evsel *evsel,
 						 struct perf_sample *sample,
···
 }
 
 const struct evsel_str_handler workqueue_tp_handlers[] = {
-	{ "workqueue:workqueue_activate_work", NULL, },
+	{ "workqueue:workqueue_activate_work", process_workqueue_activate_work_event, },
 	{ "workqueue:workqueue_execute_start", process_workqueue_execute_start_event, },
 	{ "workqueue:workqueue_execute_end",   process_workqueue_execute_end_event,   },
 };