[tip:sched/urgent] sched/stat: Expose /proc/pid/ schedstat if CONFIG_SCHED_INFO=y

[tip-bot for Naveen N. Rao]

Commit-ID:  74ed568374f0e74d80a63ab5496bf32db641ec60
Gitweb:     http://git.kernel.org/tip/74ed568374f0e74d80a63ab5496bf32db641ec60
Author:     Naveen N. Rao <naveen.n.rao@xxxxxxxxxxxxxxxxxx>
AuthorDate: Tue, 30 Jun 2015 14:36:03 +0530
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 1 Jul 2015 10:02:58 +0200

sched/stat: Expose /proc/pid/schedstat if CONFIG_SCHED_INFO=y

Expand /proc/pid/schedstat output:

 - enable it on CONFIG_TASK_DELAY_ACCT=y && !CONFIG_SCHEDSTATS kernels.

 - dump all zeroes on kernels that are booted with the 'nodelayacct'
   option, which boot option disables delay accounting on
   CONFIG_TASK_DELAY_ACCT=y kernels.

Signed-off-by: Naveen N. Rao <naveen.n.rao@xxxxxxxxxxxxxxxxxx>
Cc: Balbir Singh <bsingharora@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: a.p.zijlstra@xxxxxxxxx
Cc: ricklind@xxxxxxxxxx
Link: http://lkml.kernel.org/r/5ccbef17d4bc841084ea6e6421d4e4a23b7b806f.1435654789.git.naveen.n.rao@xxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 fs/proc/base.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 286a422..ad63fa3 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -304,14 +304,17 @@ static int proc_pid_stack(struct seq_file *m, struct pid_namespace *ns,
 }
 #endif
 
-#ifdef CONFIG_SCHEDSTATS
+#ifdef CONFIG_SCHED_INFO
 /*
  * Provides /proc/PID/schedstat
  */
 static int proc_pid_schedstat(struct seq_file *m, struct pid_namespace *ns,
 			      struct pid *pid, struct task_struct *task)
 {
-	seq_printf(m, "%llu %llu %lu\n",
+	if (unlikely(!sched_info_on()))
+		seq_printf(m, "0 0 0\n");
+	else
+		seq_printf(m, "%llu %llu %lu\n",
 		   (unsigned long long)task->se.sum_exec_runtime,
 		   (unsigned long long)task->sched_info.run_delay,
 		   task->sched_info.pcount);
@@ -2600,7 +2603,7 @@ static const struct pid_entry tgid_base_stuff[] = {
 #ifdef CONFIG_STACKTRACE
 	ONE("stack",      S_IRUSR, proc_pid_stack),
 #endif
-#ifdef CONFIG_SCHEDSTATS
+#ifdef CONFIG_SCHED_INFO
 	ONE("schedstat",  S_IRUGO, proc_pid_schedstat),
 #endif
 #ifdef CONFIG_LATENCYTOP
@@ -2948,7 +2951,7 @@ static const struct pid_entry tid_base_stuff[] = {
 #ifdef CONFIG_STACKTRACE
 	ONE("stack",      S_IRUSR, proc_pid_stack),
 #endif
-#ifdef CONFIG_SCHEDSTATS
+#ifdef CONFIG_SCHED_INFO
 	ONE("schedstat", S_IRUGO, proc_pid_schedstat),
 #endif
 #ifdef CONFIG_LATENCYTOP
--
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