[RFC PATCH 4/4] sched/core: Do numa balance in cfs_migration

Yafang Shao
2021-11-04T14:57:44Z

Similar to active load balance, the numa balance work is also applied to
cfs tasks only and it should't preempt other FIFO tasks. We'd better assign
cfs_migration to the numa balance as well.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
---
kernel/sched/core.c | 2 +-
kernel/sched/fair.c | 13 +++++++++++++
kernel/sched/sched.h | 2 ++
3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 9cb81ef8acc8..4a37b06715f4 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -8724,7 +8724,7 @@ int migrate_task_to(struct task_struct *p, int target_cpu)
/* TODO: This is not properly updating schedstats */

trace_sched_move_numa(p, curr_cpu, target_cpu);
- return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg);
+ return wakeup_cfs_migrater(curr_cpu, migration_cpu_stop, &arg);
}

/*
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 932f63baeb82..b7a155e05c98 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -11960,6 +11960,19 @@ static void wakeup_cfs_migrater_nowait(unsigned int cpu, cpu_stop_fn_t fn, void
cfs_migration_queue_work(cpu, work_buf);
}

+bool wakeup_cfs_migrater(unsigned int cpu, cpu_stop_fn_t fn, void *arg)
+{
+ struct cpu_stop_done done;
+ struct cpu_stop_work work = { .fn = fn, .arg = arg, .done = &done, .caller = _RET_IP_ };
+
+ cpu_stop_init_done(&done, 1);
+ cfs_migration_queue_work(cpu, &work);
+ cond_resched();
+ wait_for_completion(&done.completion);
+
+ return done.ret;
+}
+
static int cfs_migration_should_run(unsigned int cpu)
{
struct cfs_migrater *migrater = &per_cpu(cfs_migrater, cpu);
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index a00fc7057d97..7b242c18a6d8 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -3055,6 +3055,8 @@ static inline bool is_per_cpu_kthread(struct task_struct *p)

return true;
}
+
+bool wakeup_cfs_migrater(unsigned int cpu, cpu_stop_fn_t fn, void *arg);
#endif

extern void swake_up_all_locked(struct swait_queue_head *q);
--
2.17.1