Add a new stat,
- nr_migrations_cpu_non_preferred: number of migrations happened since
  a CPU was marked as non preferred due to high steal time.

Signed-off-by: Shrikanth Hegde <[email protected]>
---
 include/linux/sched.h | 1 +
 kernel/sched/core.c   | 9 +++++++--
 kernel/sched/debug.c  | 1 +
 3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 968b18a7f470..37849d2f1dbd 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -554,6 +554,7 @@ struct sched_statistics {
        u64                             nr_failed_migrations_running;
        u64                             nr_failed_migrations_hot;
        u64                             nr_forced_migrations;
+       u64                             nr_migrations_cpu_non_preferred;
 
        u64                             nr_wakeups;
        u64                             nr_wakeups_sync;
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 704043531b24..f0d9bcfd35e3 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -11324,8 +11324,13 @@ static int sched_non_preferred_cpu_push_stop(void *arg)
        context_unsafe_alias(rq);
 
        if (task_rq(p) == rq && task_on_rq_queued(p) &&
-           !is_migration_disabled(p))
-               rq = __migrate_task(rq, &rf, p, cpu);
+           !is_migration_disabled(p)) {
+               struct rq *dest_rq = __migrate_task(rq, &rf, p, cpu);
+
+               if (rq != dest_rq)
+                       schedstat_inc(p->stats.nr_migrations_cpu_non_preferred);
+               rq = dest_rq;
+       }
 
        rq_unlock(rq, &rf);
        raw_spin_unlock_irq(&p->pi_lock);
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 72236db67983..5ebb2055e6d5 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -1446,6 +1446,7 @@ void proc_sched_show_task(struct task_struct *p, struct 
pid_namespace *ns,
                P_SCHEDSTAT(nr_failed_migrations_running);
                P_SCHEDSTAT(nr_failed_migrations_hot);
                P_SCHEDSTAT(nr_forced_migrations);
+               P_SCHEDSTAT(nr_migrations_cpu_non_preferred);
                P_SCHEDSTAT(nr_wakeups);
                P_SCHEDSTAT(nr_wakeups_sync);
                P_SCHEDSTAT(nr_wakeups_migrate);
-- 
2.47.3


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