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* [PATCH] tools lib traceevent: Fix prev/next_prio for deadline tasks
@ 2017-01-03 11:42 Daniel Bristot de Oliveira
  2017-01-03 14:46 ` Arnaldo Carvalho de Melo
                   ` (2 more replies)
  0 siblings, 3 replies; 7+ messages in thread
From: Daniel Bristot de Oliveira @ 2017-01-03 11:42 UTC (permalink / raw)
  To: Arnaldo Carvalho de Melo, Steven Rostedt, linux-kernel
  Cc: Daniel Bristot de Oliveiva, Ingo Molnar, Peter Zijlstra,
	Alexander Shishkin, Jiri Olsa

From: Daniel Bristot de Oliveiva <bristot@redhat.com>

Currently, the sched:sched_switch tracepoint reports deadline tasks
with priority -1. But when reading the trace via perf script I've
got the following output:

  # ./d & # (d is a deadline task, see [1])
  # perf record -e sched:sched_switch -a sleep 1
  # perf script
      ...
         swapper     0 [000]  2146.962441: sched:sched_switch: swapper/0:0 [120] R ==> d:2593 [4294967295]
               d  2593 [000]  2146.972472: sched:sched_switch: d:2593 [4294967295] R ==> g:2590 [4294967295]

The task d reports the wrong priority [4294967295]. This happens because
the "int prio" is stored in an unsigned long long val. Although it is
set as a %lld, as int is shorter than unsigned long long,
trace_seq_printf prints it as a positive number.

The fix is just to cast the val as an int, and print it as a %d,
as in the sched:sched_switch tracepoint's "format".

The output with the fix is:

  # ./d &
  # perf record -e sched:sched_switch -a sleep 1
  # perf script
      ...
         swapper     0 [000]  4306.374037: sched:sched_switch: swapper/0:0 [120] R ==> d:10941 [-1]
               d 10941 [000]  4306.383823: sched:sched_switch: d:10941 [-1] R ==> swapper/0:0 [120]

[1] gcc -o d d.c - from http://bristot.me/lkml/d.c

Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: linux-kernel@vger.kernel.org

diff --git a/tools/lib/traceevent/plugin_sched_switch.c b/tools/lib/traceevent/plugin_sched_switch.c
index f1ce600..ec30c2f 100644
--- a/tools/lib/traceevent/plugin_sched_switch.c
+++ b/tools/lib/traceevent/plugin_sched_switch.c
@@ -111,7 +111,7 @@ static int sched_switch_handler(struct trace_seq *s,
 	trace_seq_printf(s, "%lld ", val);
 
 	if (pevent_get_field_val(s, event, "prev_prio", record, &val, 0) == 0)
-		trace_seq_printf(s, "[%lld] ", val);
+		trace_seq_printf(s, "[%d] ", (int) val);
 
 	if (pevent_get_field_val(s,  event, "prev_state", record, &val, 0) == 0)
 		write_state(s, val);
@@ -129,7 +129,7 @@ static int sched_switch_handler(struct trace_seq *s,
 	trace_seq_printf(s, "%lld", val);
 
 	if (pevent_get_field_val(s, event, "next_prio", record, &val, 0) == 0)
-		trace_seq_printf(s, " [%lld]", val);
+		trace_seq_printf(s, " [%d]", (int) val);
 
 	return 0;
 }
-- 
2.9.3

^ permalink raw reply related	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2017-01-05  7:55 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2017-01-03 11:42 [PATCH] tools lib traceevent: Fix prev/next_prio for deadline tasks Daniel Bristot de Oliveira
2017-01-03 14:46 ` Arnaldo Carvalho de Melo
2017-01-03 15:01   ` Daniel Bristot de Oliveira
2017-01-03 15:12     ` Arnaldo Carvalho de Melo
2017-01-03 15:29       ` Daniel Bristot de Oliveira
2017-01-03 15:00 ` Steven Rostedt
2017-01-05  7:52 ` [tip:perf/urgent] " tip-bot for Daniel Bristot de Oliveira

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