sched_dl_global

int sched_dl_global_validate(void)
{
    u64 runtime = global_rt_runtime();
    u64 period = global_rt_period();
    u64 new_bw = to_ratio(period, runtime);
    struct dl_bw *dl_b;
    int cpu, ret = 0;
    unsigned long flags;
 
    /*
     * Here we want to check the bandwidth not being set to some
     * value smaller than the currently allocated bandwidth in
     * any of the root_domains.
     *
     * FIXME: Cycling on all the CPUs is overdoing, but simpler than
     * cycling on root_domains... Discussion on different/better
     * solutions is welcome!
     */
    for_each_possible_cpu(cpu) {
        rcu_read_lock_sched();
        dl_b = dl_bw_of(cpu);
 
        raw_spin_lock_irqsave(&dl_b->lock, flags);
        if (new_bw < dl_b->total_bw)
            ret = -EBUSY;
        raw_spin_unlock_irqrestore(&dl_b->lock, flags);
 
        rcu_read_unlock_sched();
 
        if (ret)
            break;
    }
 
    return ret;
}
函数源码
