linux.conf.au, January 2003
      PROGRAMMING: kernel/softirq.c

 	/*
 	 * we cannot loop indefinitely here to avoid userspace starvation,
 	 * but we also don't want to introduce a worst case 1/HZ latency
 	 * to the pending events, so lets the scheduler to balance
 	 * the softirq load for us.
 	 */
 	static inline void wakeup_softirqd(unsigned cpu)
 	{
 	 	struct task_struct * tsk = ksoftirqd_task(cpu);
 	
 	 	if (tsk && tsk->state != TASK_RUNNING)
 	 		wake_up_process(tsk);
 	}
 
 	asmlinkage void do_softirq()
 	{
 		__u32 pending;
 		long flags;
 		__u32 mask;
 		int cpu;
 	
 		if (in_interrupt())
 			return;
 	
 		local_irq_save(flags);
 		cpu = smp_processor_id();