调度子系统3_周期调度器

来源：互联网发布：淘宝小卖家怎么定位编辑：程序博客网时间：2024/05/19 00:52
//周期调度器//调用路径：update_process_times->scheduler_tick//函数任务：//1.更新rq的clock//2.更新队列负载//3.通知调度器类更新进程运行时间//4.更新下一次load balance的时间戳//5.触发load balance1.1 void scheduler_tick(void){int cpu = smp_processor_id();struct rq *rq = cpu_rq(cpu);//当前运行的进程struct task_struct *curr = rq->curr;raw_spin_lock(&rq->lock);//更新rq的clockupdate_rq_clock(rq);//更新队列负载update_cpu_load_active(rq);//更新进程的运行时间curr->sched_class->task_tick(rq, curr, 0);raw_spin_unlock(&rq->lock);#ifdef CONFIG_SMP//更新下一次load balance的时间戳rq->idle_balance = idle_cpu(cpu);//触发load balance软中断trigger_load_balance(rq, cpu);#endif}//更新队列负载(rq->cpu_load[])//每scheduler tick(TICK_NSEC)被调用一次//函数任务：//1.更新rq负载//1.1 通过CPU_LOAD_IDX_MAX个项记录rq的历史负载信息//1.2 更新方法//cpu_load[0] = load.weight//cpu_load[1] = (cpu_load[1]   + load.weight)/2//cpu_load[2] = (cpu_load[2]*3 + load.weight)/4//cpu_load[3] = (cpu_load[2]*7 + load.weight)/8//2.如果当前时间到达计算cpu负载的时间点//2.1 更新下一次计算cpu负载的时间点//2.2 计算cpu负载//调用路径：scheduler_tick->update_cpu_load2.1 static void update_cpu_load(struct rq *this_rq){//rq中所有se负载的总和unsigned long this_load = this_rq->load.weight;int i, scale;this_rq->nr_load_updates++;//通过CPU_LOAD_IDX_MAX个项记录rq的历史负载信息for (i = 0, scale = 1; i < CPU_LOAD_IDX_MAX; i++, scale += scale) {unsigned long old_load, new_load;old_load = this_rq->cpu_load[i];//rq中所有se的load.weight之和new_load = this_load;if (new_load > old_load)new_load += scale-1;//cpu_load[0] = load.weight//cpu_load[1] = (cpu_load[1]   + load.weight)/2//cpu_load[2] = (cpu_load[2]*3 + load.weight)/4//cpu_load[3] = (cpu_load[2]*7 + load.weight)/8//....this_rq->cpu_load[i] = (old_load*(scale-1) + new_load) >> i;}//到达计算cpu负载的时间点if (time_after_eq(jiffies, this_rq->calc_load_update)) {//更新下一次计算cpu负载的时间点this_rq->calc_load_update += LOAD_FREQ;//计算系统负载calc_load_account_active(this_rq);}}//计算系统负载//系统负载考虑就绪状态进程和不可中断睡眠的进程(I/O)进程//调用路径：update_cpu_load->calc_load_account_active2.2 static void calc_load_account_active(struct rq *this_rq){long nr_active, delta;nr_active = this_rq->nr_running;//就绪状态的进程nr_active += (long) this_rq->nr_uninterruptible;//不可中断睡眠的进程if (nr_active != this_rq->calc_load_active) {delta = nr_active - this_rq->calc_load_active;this_rq->calc_load_active = nr_active;atomic_long_add(delta, &calc_load_tasks);}}
0 0