LinuxMemo

主にDebian/GNU Linux （etch以降）についての覚書き

目次

カーネル

タスクスケジューラ

カーネル2.5時点での情報: [後藤,2002]

root権限でスケジューラに対して，プロセスがactive queueにあり続けるように
すれば，そのプロセスがCPUを独占できる?（--> 計測/制御プログラムの場合，有用）
2.4.22時点での情報のようにgettimeofday()とnanosleep()を組み合わせれば十分?

reemptive kernelの場合は?

カーネル2.6.18，sched.c, 555行

/*
 * Called when a process is dequeued from the active array and given
 * the cpu.  We should note that with the exception of interactive
 * tasks, the expired queue will become the active queue after the active
 * queue is empty, without explicitly dequeuing and requeuing tasks in the
 * expired queue.  (Interactive tasks may be requeued directly to the
 * active queue, thus delaying tasks in the expired queue from running;
 * see scheduler_tick()).
 *
 * 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(struct task_struct *t)
{
	t->sched_info.last_queued = 0;
}