Add scheduler stats to record number of times preemption delay was granted
or denied.

Signed-off-by: Prakash Sangappa <prakash.sangappa@oracle.com>
---
 include/linux/sched.h |  8 ++++++++
 kernel/sched/core.c   | 12 ++++++++++++
 kernel/sched/debug.c  |  4 ++++
 mm/task_shared.c      |  2 ++
 4 files changed, 26 insertions(+)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index b53e7a878a01..e3f5760632f4 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -327,6 +327,10 @@ extern void io_schedule_finish(int token);
 extern long io_schedule_timeout(long timeout);
 extern void io_schedule(void);
 extern void hrtick_local_start(u64 delay);
+#ifdef CONFIG_TASKSHARED
+extern void update_stat_preempt_delayed(struct task_struct *t);
+extern void update_stat_preempt_denied(struct task_struct *t);
+#endif
 
 /**
  * struct prev_cputime - snapshot of system and user cputime
@@ -532,6 +536,10 @@ struct sched_statistics {
 	u64				nr_wakeups_affine_attempts;
 	u64				nr_wakeups_passive;
 	u64				nr_wakeups_idle;
+#ifdef CONFIG_TASKSHARED
+	u64				nr_preempt_delay_granted;
+	u64				nr_preempt_delay_denied;
+#endif
 
 #ifdef CONFIG_SCHED_CORE
 	u64				core_forceidle_sum;
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 713c43491403..54fa4b68adaf 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -916,6 +916,18 @@ void hrtick_local_start(u64 delay)
 	rq_unlock(rq, &rf);
 }
 
+#ifdef CONFIG_TASKSHARED
+void update_stat_preempt_delayed(struct task_struct *t)
+{
+	schedstat_inc(t->stats.nr_preempt_delay_granted);
+}
+
+void update_stat_preempt_denied(struct task_struct *t)
+{
+	schedstat_inc(t->stats.nr_preempt_delay_denied);
+}
+#endif
+
 static void hrtick_rq_init(struct rq *rq)
 {
 #ifdef CONFIG_SMP
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 4a9fbbe843c0..ace7856f13c3 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -1215,6 +1215,10 @@ void proc_sched_show_task(struct task_struct *p, struct pid_namespace *ns,
 		P_SCHEDSTAT(nr_wakeups_affine_attempts);
 		P_SCHEDSTAT(nr_wakeups_passive);
 		P_SCHEDSTAT(nr_wakeups_idle);
+#ifdef CONFIG_TASKSHARED
+		P_SCHEDSTAT(nr_preempt_delay_granted);
+		P_SCHEDSTAT(nr_preempt_delay_denied);
+#endif
 
 		avg_atom = p->se.sum_exec_runtime;
 		if (nr_switches)
diff --git a/mm/task_shared.c b/mm/task_shared.c
index 5b8a068a6b44..35aecc718c8e 100644
--- a/mm/task_shared.c
+++ b/mm/task_shared.c
@@ -285,6 +285,7 @@ bool taskshrd_delay_resched(void)
 			/* not granted */
 			shrdp->kaddr->ts.sched_delay
 				= TASK_PREEMPT_DELAY_DENIED;
+			update_stat_preempt_denied(t);
 		}
 		return false;
 	}
@@ -295,6 +296,7 @@ bool taskshrd_delay_resched(void)
 	/* granted */
 	shrdp->kaddr->ts.sched_delay = TASK_PREEMPT_DELAY_GRANTED;
 	t->taskshrd_sched_delay = 1;
+	update_stat_preempt_delayed(t);
 
 	return true;
 }
-- 
2.43.5