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charset="utf-8" When a CPU becomes parked, all tasks present on that CPU should vacate it. Use existing __balance_push_cpu_stop mechanism to move out current running task.=20 Which CPUs need to be parked is to be decided by architecture.=20 Signed-off-by: Shrikanth Hegde --- Note: Maybe this could be done only for CFS, EXT tasks if it is not recommended for RT,DL etc.=20 kernel/sched/core.c | 39 +++++++++++++++++++++++++++++++++++++++ kernel/sched/sched.h | 1 + 2 files changed, 40 insertions(+) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 9ec12f9b3b08..dd8e824bc030 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5656,6 +5656,10 @@ void sched_tick(void) =20 sched_clock_tick(); =20 + /* push the current task out if cpu is parked */ + if (cpu_parked(cpu)) + push_current_task(rq); + rq_lock(rq, &rf); donor =3D rq->donor; =20 @@ -8482,6 +8486,41 @@ void __init sched_init_smp(void) } #endif /* CONFIG_SMP */ =20 +#if defined(CONFIG_SMP) && defined(CONFIG_HOTPLUG_CPU) +static DEFINE_PER_CPU(struct cpu_stop_work, push_task_work); + +/* A parked CPU is when underlying physical CPU is not available. + * Scheduling on such CPU is going to cause OS preemption. + * In case any task is scheduled on such CPU, move it out. In + * select_fallback_rq a non parked CPU will be chosen and henceforth + * task shouldn't come back to this CPU + */ +void push_current_task(struct rq *rq) +{ + struct task_struct *push_task =3D rq->curr; + unsigned long flags; + + /* idle task can't be pused out */ + if (rq->curr =3D=3D rq->idle || !cpu_parked(rq->cpu)) + return; + + if (kthread_is_per_cpu(push_task) || + is_migration_disabled(push_task)) + return; + + local_irq_save(flags); + get_task_struct(push_task); + preempt_disable(); + + stop_one_cpu_nowait(rq->cpu, __balance_push_cpu_stop, push_task, + this_cpu_ptr(&push_task_work)); + preempt_enable(); + local_irq_restore(flags); +} +#else +void push_current_task(struct rq *rq) { }; +#endif + int in_sched_functions(unsigned long addr) { return in_lock_functions(addr) || diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index c5a6a503eb6d..86bcd9401d41 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -104,6 +104,7 @@ extern void calc_global_load_tick(struct rq *this_rq); extern long calc_load_fold_active(struct rq *this_rq, long adjust); =20 extern void call_trace_sched_update_nr_running(struct rq *rq, int count); +void push_current_task(struct rq *rq); =20 extern int sysctl_sched_rt_period; extern int sysctl_sched_rt_runtime; --=20 2.39.3