A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail?
On Wed, Jun 03, 2015 at 04:24:05PM +0800, [email protected] wrote: > Hi Peter, > > This may increase the overhead of schedule() a bit, as it will have > more work to do. How so? It replaces the post_schedule() muck and should not be more expensive than that. It will make sched_setscheduler() etc.. a little more expensive, but that doesn't matter, those are not critical things at all. > check_class_changed(): > if (prev_class->switched_from) > prev_class->switched_from(rq, p); > /* Possble rq->lock 'hole'. */ > p->sched_class->switched_to(rq, p); > > For above cases, why can't we just add a judgement in switched_to_fair() > as follows: > if (rq != task_rq(p)) > return; Because its too easy to get wrong. There have been many instances of bugs caused by this dropping of rq->lock. And sure you can patch it up, once you find it, but I would really rather prevent these things if at all possible. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
