[PATCH v14 09/13] sched/debug: Add migration stats due to non preferred CPUs
From: Shrikanth Hegde <sshegde@linux.ibm.com>
Date: 2026-09-28 05:40:07
Also in:
lkml, virtualization
Subsystem:
scheduler, the rest · Maintainers:
Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot, Linus Torvalds
Add a new per-task stat, - nr_migrations_cpu_non_preferred: number of push migrations while the CPU is non-preferred. Since this new stat is per-task, it changes only /proc/<pid>/sched. It doesn't update /proc/schedstat. Hence increasing the schedstat version is not necessary. Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com> --- 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 d7cc77181ef9..48639b0c75d0 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 5049eff58fb7..7465c983e6f6 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c@@ -11236,8 +11236,13 @@ static int sched_non_preferred_cpu_push_stop(void *arg) update_rq_clock(rq); context_unsafe_alias(rq); - if (task_rq(p) == rq && task_on_rq_queued(p)) - rq = __migrate_task(rq, &rf, p, cpu); + if (task_rq(p) == rq && task_on_rq_queued(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); }
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index fda10b3fa249..e6a3b516c703 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c@@ -1440,6 +1440,7 @@ 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);
--
2.52.0