perf sched timehist: Mark schedule function in callchains

The sched_switch event always captured from the scheduler function.  So
it'd be great omit them from the callchain.  This patch marks the
functions to be omitted by later patch.

Committer notes:

Testing it:

Before:

  [root@jouet experimental]# perf sched record -g ls
  Dockerfile  perf.data  x-mips64
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 1.355 MB perf.data (29 samples) ]
  [root@jouet experimental]# perf sched timehist
      time  cpu  task name         wait time sch delay run time
                 [tid/pid]             (msec) (msec) (msec)
  ----------- -----  ----------------- ------ ------ ------
  6.494998 [001] <idle>                0.000  0.000  0.000
  6.495027 [002] perf[519]             0.000  0.000  0.000 __schedule <- schedule <- schedule_hrtimeout_range_clock <- schedule_hrtimeou
  6.495096 [003] <idle>                0.000  0.000  0.000
  6.495100 [003] rcuos/0[9]            0.000  0.005  0.003 __schedule <- schedule <- rcu_nocb_kthread <- kthread <- ret_from_fork
  6.495113 [001] perf[520]             0.000  0.008  0.114 __schedule <- preempt_schedule_common <- _cond_resched <- wait_for_completion
  6.495121 [000] <idle>                0.000  0.000  0.000
  6.495129 [001] migration/1[17]       0.000  0.003  0.016 __schedule <- schedule <- smpboot_thread_fn <- kthread <- ret_from_fork
  6.496085 [002] <idle>                0.000  0.000  1.057
  6.496096 [002] kworker/u16:1[31169]  0.000  0.004  0.011 __schedule <- schedule <- worker_thread <- kthread <- ret_from_fork
  6.496096 [003] <idle>                0.003  0.000  0.996
  6.496169 [002] <idle>                0.011  0.000  0.072
  6.496171 [000] ls[520]               0.008  0.000  1.049 __schedule <- schedule <- do_exit <- do_group_exit <- [unknown]
  6.496172 [003] gnome-terminal-[4391] 0.000  0.003  0.076 __schedule <- schedule <- schedule_hrtimeout_range_clock <- schedule_hrtimeo

After:

  [root@jouet experimental]# perf sched timehist
      time  cpu  task name         wait time sch delay run time
                 [tid/pid]            (msec)  (msec)  (msec)
  ----------- -----  ----------------- -----  -----  ------
  6.494998 [001] <idle>                0.000  0.000  0.000
  6.495027 [002] perf[519]             0.000  0.000  0.000 schedule_hrtimeout_range_clock <- schedule_hrtimeout_range <- poll_schedule_t
  6.495096 [003] <idle>                0.000  0.000  0.000
  6.495100 [003] rcuos/0[9]            0.000  0.005  0.003 rcu_nocb_kthread <- kthread <- ret_from_fork
  6.495113 [001] perf[520]             0.000  0.008  0.114 preempt_schedule_common <- _cond_resched <- wait_for_completion <- stop_one_c
  6.495121 [000] <idle>                0.000  0.000  0.000
  6.495129 [001] migration/1[17]       0.000  0.003  0.016 smpboot_thread_fn <- kthread <- ret_from_fork
  6.496085 [002] <idle>                0.000  0.000  1.057
  6.496096 [002] kworker/u16:1[31169]  0.000  0.004  0.011 worker_thread <- kthread <- ret_from_fork
  6.496096 [003] <idle>                0.003  0.000  0.996
  6.496169 [002] <idle>                0.011  0.000  0.072
  6.496171 [000] ls[520]               0.008  0.000  1.049 do_exit <- do_group_exit <- [unknown]
  6.496172 [003] gnome-terminal-[4391] 0.000  0.003  0.076 schedule_hrtimeout_range_clock <- schedule_hrtimeout_range <- poll_schedule_
  [root@jouet experimental]#

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20161124011114.7102-1-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-sched.c

@@ -1966,7 +1966,28 @@ static bool is_idle_sample(struct perf_sched *sched,
 
 		return false;
 	}
+
 	callchain_cursor_commit(cursor);
+
+	while (true) {
+		struct callchain_cursor_node *node;
+		struct symbol *sym;
+
+		node = callchain_cursor_current(cursor);
+		if (node == NULL)
+			break;
+
+		sym = node->sym;
+		if (sym && sym->name) {
+			if (!strcmp(sym->name, "schedule") ||
+			    !strcmp(sym->name, "__schedule") ||
+			    !strcmp(sym->name, "preempt_schedule"))
+				sym->ignore = 1;
+		}
+
+		callchain_cursor_advance(cursor);
+	}
+
 	return false;
 }
 

tools/perf/util/symbol.h

@@ -58,6 +58,7 @@ struct symbol {
 	u16		namelen;
 	u8		binding;
 	u8		idle:1;
+	u8		ignore:1;
 	u8		arch_sym;
 	char		name[0];
 };