Re: Staircase v7.4 question.

[Con Kolivas <kernel@kolivas.org>]

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Adrian Drzewiecki wrote:
| Hi Con,
|  Wonderful job on the scheduler! I really like the simplicity of
staircase
| vs mainline, and am very happy with its behaviour.
| I was hand-applying the patch from 7.3 to 7.4, and 'enqueue_task' seemed
| inconsistant from your description:
|
| 	"Preempted tasks [...] will go ahead of other tasks [...]"
|
| The code is:
|
| 	static void enqueue_task(struct task_struct *p, runqueue_t *rq)
| 	{
| 		if (rq->curr->flags & PF_PREEMPTED) {
| 			rq->curr->flags &= ~PF_PREEMPTED;
| 			list_add(&p->run_list, rq->queue + p->prio);
| 		} else
| 			list_add_tail(&p->run_list, rq->queue + p->prio);
| 		__set_bit(p->prio, rq->bitmap);
| 	}
|
| This would insert other tasks in front of a task which was just preempted.
| Shouldn't the code be:
|
| 		if (p->flags & PF_PREEMPTED) {
| 			p->flags &= ~PF_PREEMPTED;
| 			....

Eeek!

Indeed. Brain fart. Looks like I introduced a couple of bugs here after
all :P

Con
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