linux-kernel - [PATCH 08/12] perf sched timehist: Enlarge max stack depth by 2

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Message-Id: <1480086747-2393-9-git-send-email-acme@kernel.org>
Date:   Fri, 25 Nov 2016 12:12:23 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     linux-kernel@...r.kernel.org, Namhyung Kim <namhyung@...nel.org>,
        Andi Kleen <andi@...stfloor.org>,
        David Ahern <dsahern@...il.com>, Jiri Olsa <jolsa@...nel.org>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Stephane Eranian <eranian@...gle.com>,
        Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: [PATCH 08/12] perf sched timehist: Enlarge max stack depth by 2

From: Namhyung Kim <namhyung@...nel.org>

When it records callchains, they will always have 2 scheduler functions
(__schedule + schedule or __schedule + preempt_schedule) and get
ignored.  So it should collect 2 more functions to show the expected
number of callchains to user.

Committer Notes:

Example of final result, using the same perf.data file as in the
previous cset comment, but this time redirecting the output of 'perf
sched timehist' to a file instead of copy'n'pasting from xterm:

  [root@...et experimental]# perf sched timehist > /tmp/bla
  [root@...et experimental]# cat /tmp/bla
      time  cpu task name        wait time sch delay run time
                 [tid/pid]            (msec) (msec) (msec)
  -------- ----  -------------------- ------ ------ -----
  6.494998 [01] <idle>                0.000  0.000  0.000
  6.495027 [02] perf[519]             0.000  0.000  0.000 schedule_hrtimeout_range_clock <- schedule_hrtimeout_range <- poll_schedule_timeout <- do_sys_poll <- sys_poll
  6.495096 [03] <idle>                0.000  0.000  0.000
  6.495100 [03] rcuos/0[9]            0.000  0.005  0.003 rcu_nocb_kthread <- kthread <- ret_from_fork
  6.495113 [01] perf[520]             0.000  0.008  0.114 preempt_schedule_common <- _cond_resched <- wait_for_completion <- stop_one_cpu <- sched_exec <- do_execveat_common.isra.35
  6.495121 [00] <idle>                0.000  0.000  0.000
  6.495129 [01] migration/1[17]       0.000  0.003  0.016 smpboot_thread_fn <- kthread <- ret_from_fork
  6.496085 [02] <idle>                0.000  0.000  1.057
  6.496096 [02] kworker/u16:1[31169]  0.000  0.004  0.011 worker_thread <- kthread <- ret_from_fork
  6.496096 [03] <idle>                0.003  0.000  0.996
  6.496169 [02] <idle>                0.011  0.000  0.072
  6.496171 [00] ls[520]               0.008  0.000  1.049 do_exit <- do_group_exit <- [unknown] <- entry_SYSCALL_64_fastpath
  6.496172 [03] gnome-terminal-[4391] 0.000  0.003  0.076 schedule_hrtimeout_range_clock <- schedule_hrtimeout_range <- poll_schedule_timeout <- do_sys_poll <- sys_poll

Signed-off-by: Namhyung Kim <namhyung@...nel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Andi Kleen <andi@...stfloor.org>
Cc: David Ahern <dsahern@...il.com>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Stephane Eranian <eranian@...gle.com>
Link: http://lkml.kernel.org/r/20161124011114.7102-3-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/builtin-sched.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index 06be809a02ab..a49a032f5b15 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -1960,7 +1960,7 @@ static bool is_idle_sample(struct perf_sched *sched,
 		return false;
 
 	if (thread__resolve_callchain(thread, cursor, evsel, sample,
-				      NULL, NULL, sched->max_stack) != 0) {
+				      NULL, NULL, sched->max_stack + 2) != 0) {
 		if (verbose)
 			error("Failed to resolve callchain. Skipping\n");
 
-- 
2.7.4