中断学习之timer_interrupt powerpc实现

#define DECREMENTER_EXCEPTION						      \
	START_EXCEPTION(Decrementer)					      \
	NORMAL_EXCEPTION_PROLOG;					      \
	lis     r0,TSR_DIS@h;           /* Setup the DEC interrupt mask */    \
	mtspr   SPRN_TSR,r0;		/* Clear the DEC interrupt */	      \
	addi    r3,r1,STACK_FRAME_OVERHEAD;				      \
	EXC_XFER_LITE(0x0900, timer_interrupt)

	
void timer_interrupt(struct pt_regs * regs)
	=>int cpu = smp_processor_id();
	=>if (atomic_read(&ppc_n_lost_interrupts) != 0)//如果还有未处理的外部中断处理函数，则处理
		do_IRQ(regs);
	=>old_regs = set_irq_regs(regs);//保存寄存器现场，注意old_regs是指针，指向现场全局寄存器的指针
		=>struct pt_regs *old_regs, **pp_regs = &__get_cpu_var(__irq_regs);//保存在__irq_regs全局变量里面，每个核一个
		old_regs = *pp_regs;
		*pp_regs = new_regs;
		return old_regs
	=>irq_enter();//中断计数加一，进入中断上下文
	=>while ((ticks = tb_ticks_since(per_cpu(last_jiffy, cpu))) >= tb_ticks_per_jiffy)
		per_cpu(last_jiffy, cpu) += tb_ticks_per_jiffy;
		account_process_time(regs);//#define account_process_time(regs)	update_process_times(user_mode(regs))
			=>scheduler_tick();//选择合适的进程，用于时钟中断返回继续调度
				=>curr->sched_class->task_tick(rq, curr);//.task_tick		= task_tick_fair
					=>struct sched_entity *se = &curr->se;
					=>for_each_sched_entity(se) {
						cfs_rq = cfs_rq_of(se);
						entity_tick(cfs_rq, se);
					}
		if (cpu != boot_cpuid)
			continue;
		tb_next_jiffy = tb_last_jiffy + tb_ticks_per_jiffy;
		if (per_cpu(last_jiffy, cpu) >= tb_next_jiffy) {
			tb_last_jiffy = tb_next_jiffy;
			do_timer(1);
			timer_recalc_offset(tb_last_jiffy);
			timer_check_rtc();
		}
	=>next_dec = tb_ticks_per_jiffy - ticks;
	=>set_dec(next_dec);//设置DEC寄存器，用于触发下一次的时钟中断
	=>irq_exit();
	=>set_irq_regs(old_regs);

 

如下两个人的博客都挺好的

 

时钟中断（1）
https://blog.youkuaiyun.com/wrx1721267632/article/details/50527595


把握linux内核设计思想（六）：内核时钟中断
https://blog.youkuaiyun.com/shallnet/article/details/47132861

[收藏]时钟中断（Timer Interrupt）与 Linux内核调度
https://blog.youkuaiyun.com/don_chiang709/article/details/89181399