linux-kernel - [BUG] perf sched broken

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Date:	Wed, 12 Jan 2011 10:29:05 +0100
From:	Stephane Eranian <eranian@...gle.com>
To:	LKML <linux-kernel@...r.kernel.org>
Cc:	Frédéric Weisbecker <fweisbec@...il.com>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>, mingo@...e.hu,
	Robert Richter <robert.richter@....com>
Subject: [BUG] perf sched broken

Hi,

I am trying to use perf sched from tip-x86 but it fails for all my attempts.

First of, I think the event list is stale. This is not so much the
events themselves
but rather the flags.

Looks to me like the :r modifier is not supported anymore, so a patch like the
one below is needed. That helps collect a trace. But then, you can dump
the trace.

$ perf sched rec dd if=/dev/zero of=/dev/null count=1000000
1000000+0 records in
1000000+0 records out
512000000 bytes (512 MB) copied, 0.589981 s, 868 MB/s
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.481 MB perf.data (~20997 samples) ]

$ perf sched rep
run measurement overhead: 2934 nsecs
sleep measurement overhead: 90502 nsecs
the run test took 999149 nsecs
the sleep test took 1092248 nsecs
  Fatal: no trace data in the file

$ perf sched trace -D
 usage: perf sched [<options>] {record|latency|map|replay|trace}

    -i, --input <file>    input file name
    -v, --verbose         be more verbose (show symbol address, etc)
    -D, --dump-raw-trace  dump raw trace in ASCII

Note that this is not specific to pref sched. If I use perf record directly,
I run into the same issue:
$ perf record -R -a -c 1 -e sched:sched_switch -- sleep 1
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.365 MB perf.data (~15962 samples) ]
$./perf report -D
  Fatal: no trace data in the file

Now that perf trace is gone, how to I dump the trace?


Drop :r modifier for tracepoints

Signed-off-by: Stephane Eranian <eranian@...gle.com>
---

diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index abd4b84..29e7ffd 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -1843,15 +1843,15 @@ static const char *record_args[] = {
        "-f",
        "-m", "1024",
        "-c", "1",
-       "-e", "sched:sched_switch:r",
-       "-e", "sched:sched_stat_wait:r",
-       "-e", "sched:sched_stat_sleep:r",
-       "-e", "sched:sched_stat_iowait:r",
-       "-e", "sched:sched_stat_runtime:r",
-       "-e", "sched:sched_process_exit:r",
-       "-e", "sched:sched_process_fork:r",
-       "-e", "sched:sched_wakeup:r",
-       "-e", "sched:sched_migrate_task:r",
+       "-e", "sched:sched_switch",
+       "-e", "sched:sched_stat_wait",
+       "-e", "sched:sched_stat_sleep",
+       "-e", "sched:sched_stat_iowait",
+       "-e", "sched:sched_stat_runtime",
+       "-e", "sched:sched_process_exit",
+       "-e", "sched:sched_process_fork",
+       "-e", "sched:sched_wakeup",
+       "-e", "sched:sched_migrate_task",
 };
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