perf trace: Beautify sched_[gs]et_attr return value

Commit-ID:  f0bbd602268e69f4f428075c645391d64bdd6c9f
Gitweb:     http://git.kernel.org/tip/f0bbd602268e69f4f428075c645391d64bdd6c9f
Author:     Arnaldo Carvalho de Melo <[email protected]>
AuthorDate: Wed, 28 Sep 2016 13:45:38 -0300
Committer:  Arnaldo Carvalho de Melo <[email protected]>
CommitDate: Wed, 28 Sep 2016 13:48:04 -0300

perf trace: Beautify sched_[gs]et_attr return value

Both return errno, show the string associated then.

More work needed to capture the sched_attr arg to beautify it in turn, probably using BPF.

Before:

     0.210 ( 0.001 ms): sched_setattr(uattr: 0x7ffc684f02b0) = -22

After the patch, for this sched_attr, all other parms are zero, so not shown:

struct sched_attr attr = {
.size = sizeof(attr),
.sched_policy = SCHED_DEADLINE,
.sched_runtime = 10 * USECS_PER_SEC,
.sched_period = 30 * USECS_PER_SEC,
.sched_deadline = attr.sched_period,
};

0.321 ( 0.002 ms): sched_setattr(uattr: 0x7ffc44116da0) = -1 EINVAL Invalid argument

[root@jouet c]# perf trace -e sched_setattr ./sched_deadline Couldn't negotiate deadline: Invalid argument

     0.229 ( 0.003 ms): sched_setattr(uattr: 0x7ffd8dcd8df0) = -1 EINVAL Invalid argument

[root@jouet c]#

Now to figure out the reason for this EINVAL.

---
 tools/perf/builtin-trace.c | 2 ++
 1 file changed, 2 insertions(+)

index b4fc1ab..1a54ce9 100644
@@ -742,6 +742,8 @@ static struct syscall_fmt {
 	  .arg_scnprintf = { [1] = SCA_SIGNUM, /* sig */ }, },
 	{ .name	    = "rt_tgsigqueueinfo", .errmsg = true,
 	  .arg_scnprintf = { [2] = SCA_SIGNUM, /* sig */ }, },
+	{ .name	    = "sched_getattr",	      .errmsg = true, },
+	{ .name	    = "sched_setattr",	      .errmsg = true, },
 	{ .name	    = "sched_setscheduler",   .errmsg = true,
 	  .arg_scnprintf = { [1] = SCA_SCHED_POLICY, /* policy */ }, },
 	{ .name	    = "seccomp", .errmsg = true,