When selecting the cpu for a waking DL task, if curr is a non-DL task which is bound only on this cpu, then we can give it a chance to select a different cpu for this DL task to avoid curr starving.
Signed-off-by: pang.xunlei <[email protected]> --- kernel/sched/deadline.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 7b0b2d2..1f64d4a 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -954,6 +954,9 @@ select_task_rq_dl(struct task_struct *p, int cpu, int sd_flag, int flags) struct task_struct *curr; struct rq *rq; + if (p->nr_cpus_allowed == 1) + goto out; + if (sd_flag != SD_BALANCE_WAKE && sd_flag != SD_BALANCE_FORK) goto out; @@ -970,11 +973,14 @@ select_task_rq_dl(struct task_struct *p, int cpu, int sd_flag, int flags) * can!) we prefer to send it somewhere else. On the * other hand, if it has a shorter deadline, we * try to make it stay here, it might be important. + * + * If the current task on @p's runqueue is a non-DL task, + * and this task is bound on current runqueue, then try to + * see if we can wake this DL task up on a different runqueue, */ - if (unlikely(dl_task(curr)) && - (curr->nr_cpus_allowed < 2 || - !dl_entity_preempt(&p->dl, &curr->dl)) && - (p->nr_cpus_allowed > 1)) { + if (unlikely(curr->nr_cpus_allowed < 2) || + unlikely(dl_task(curr) && + !dl_entity_preempt(&p->dl, &curr->dl))) { int target = find_later_rq(p); if (target != -1) -- 1.7.9.5 -- 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/
