1. 數(shù)據(jù)結(jié)構(gòu)
struct sched_info {
????/* cumulative counters */
????unsigned long cpu_time, /* time spent on the cpu */
? ? ? ? ? ? ? ? ? ? ????????run_delay, /* time spent waiting on a runqueue */
? ? ? ? ? ? ? ? ? ? ????????pcnt; /* # of timeslices run on this cpu */
????/* timestamps */
? ? unsigned long last_arrival, /* when we last ran on a cpu */
? ? ? ? ? ? ? ? ? ? ????????last_queued; /* when we were last queued to run */
};
2. 場(chǎng)景解析
場(chǎng)景：進(jìn)程離開活躍任務(wù)隊(duì)列革骨，獲取到cpu資源丢间，記錄進(jìn)程的run_delay, last_arrival, pcnt, 重置last_queued酌壕。
/*
* Called when a process is dequeued from the active array and given
* the cpu.
* This function is only called from sched_info_arrive(), rather than
* dequeue_task(). Even though a task may be queued and dequeued multiple
* times as it is shuffled about, we're really interested in knowing how
* long it was from the *first* time it was queued to the time that it
* finally hit a cpu.
*/
static inline void sched_info_dequeued(task_t *t)
{
????t->sched_info.last_queued = 0;
}
/*
* Called when a task finally hits the cpu.? We can now calculate how
* long it was waiting to run.? We also note when it began so that we
* can keep stats on how long its timeslice is.
*/
static inline void sched_info_arrive(task_t *t)
{
????unsigned long now = jiffies, diff = 0;
????struct runqueue *rq = task_rq(t);
????if (t->sched_info.last_queued)
????????diff = now - t->sched_info.last_queued;
????sched_info_dequeued(t);
????t->sched_info.run_delay += diff;?
????t->sched_info.last_arrival = now;
????t->sched_info.pcnt++;
????if (!rq)
????????return;
????rq->rq_sched_info.run_delay += diff;
????rq->rq_sched_info.pcnt++;
}
場(chǎng)景：進(jìn)程釋放CPU資源雌桑，記錄進(jìn)程的CPU占用時(shí)間cpu_time舔庶。
/*
* Called when a process ceases being the active-running process, either
* voluntarily or involuntarily.? Now we can calculate how long we ran.
*/
static inline void sched_info_depart(task_t *t)
{
????struct runqueue *rq = task_rq(t);
????unsigned long diff = jiffies - t->sched_info.last_arrival;
????t->sched_info.cpu_time += diff;
????if (rq)
????????rq->rq_sched_info.cpu_time += diff;
}
