Messages in this thread Patches in this message | | | Date | Tue, 1 Jul 2008 15:32:09 +0200 | From | "Dmitry Adamushko" <> | Subject | [sched-devel, patch-rfc] rework #2 of "prioritize non-migratable tasks over migratable ones" |
| |
Hi,
this is a continuation of another thread: http://www.ussg.iu.edu/hypermail/linux/kernel/0807.0/0134.html
The following patch is just an illustration, not tested even compilation wise.
(1) handle in a generic way all cases when a newly woken-up task is not migratable (not just a corner case when "rt_se->nr_cpus_allowed == 1")
(2) if current is to be preempted, then make sure "p" will be picked up by pick_next_task_rt(). i.e. move task's group at the head of its list as well.
currently, it's not a case for group-scheduling as described here: http://www.ussg.iu.edu/hypermail/linux/kernel/0807.0/0134.html
what do you think?
(non white-space-damaged version is enclosed)
---
--- sched_rt-old.c 2008-07-01 11:42:30.000000000 +0200 +++ sched_rt.c 2008-07-01 15:00:55.000000000 +0200 @@ -599,11 +599,7 @@ static void __enqueue_rt_entity(struct s if (group_rq && (rt_rq_throttled(group_rq) || !group_rq->rt_nr_running)) return;
- if (rt_se->nr_cpus_allowed == 1) - list_add(&rt_se->run_list, queue); - else - list_add_tail(&rt_se->run_list, queue); - + list_add_tail(&rt_se->run_list, queue); __set_bit(rt_se_prio(rt_se), array->bitmap);
inc_rt_tasks(rt_se, rt_rq); @@ -689,31 +685,33 @@ static void dequeue_task_rt(struct rq *r * followed by enqueue. */ static -void requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se) +void requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se, int head) { - struct rt_prio_array *array = &rt_rq->active; - if (on_rt_rq(rt_se)) { - list_del_init(&rt_se->run_list); - list_add_tail(&rt_se->run_list, - array->queue + rt_se_prio(rt_se)); + struct rt_prio_array *array = &rt_rq->active; + struct list_head *queue = array->queue + rt_se_prio(rt_se); + + if (head) + list_move(&rt_se->run_list, queue); + else + list_move_tail(&rt_se->run_list, queue); } }
-static void requeue_task_rt(struct rq *rq, struct task_struct *p) +static void requeue_task_rt(struct rq *rq, struct task_struct *p, int head) { struct sched_rt_entity *rt_se = &p->rt; struct rt_rq *rt_rq;
for_each_sched_rt_entity(rt_se) { rt_rq = rt_rq_of_se(rt_se); - requeue_rt_entity(rt_rq, rt_se); + requeue_rt_entity(rt_rq, rt_se, head); } }
static void yield_task_rt(struct rq *rq) { - requeue_task_rt(rq, rq->curr); + requeue_task_rt(rq, rq->curr, 0); }
#ifdef CONFIG_SMP @@ -753,6 +751,29 @@ static int select_task_rq_rt(struct task */ return task_cpu(p); } + +static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p) +{ + cpumask_t mask; + + if (rq->curr.rt.nr_cpus_allowed == 1 || p->rt.nr_cpus_allowed == 1) + return; + + if (cpupri_find(&rq->rd->cpupri, p, &mask)) + return; + + if (!cpupri_find(&rq->rd->cpupri, rq->curr, &mask)) + return; + + /* + * There appears to be other cpus that can accept + * current and none to run 'p', so lets reschedule + * to try and push current away: + */ + requeue_task_rt(rq, p, 1); + resched_task(rq->curr); +} + #endif /* CONFIG_SMP */
/* @@ -778,18 +799,8 @@ static void check_preempt_curr_rt(struct * to move current somewhere else, making room for our non-migratable * task. */ - if((p->prio == rq->curr->prio) - && p->rt.nr_cpus_allowed == 1 - && rq->curr->rt.nr_cpus_allowed != 1) { - cpumask_t mask; - - if (cpupri_find(&rq->rd->cpupri, rq->curr, &mask)) - /* - * There appears to be other cpus that can accept - * current, so lets reschedule to try and push it away - */ - resched_task(rq->curr); - } + if (p->prio == rq->curr->prio && !need_resched()) + check_preempt_equal_prio(rq, p); #endif }
@@ -1415,7 +1426,7 @@ static void task_tick_rt(struct rq *rq, * on the queue: */ if (p->rt.run_list.prev != p->rt.run_list.next) { - requeue_task_rt(rq, p); + requeue_task_rt(rq, p, 0); set_tsk_need_resched(p); } } ---
-- Best regards, Dmitry Adamushko --- sched_rt-old.c 2008-07-01 11:42:30.000000000 +0200 +++ sched_rt.c 2008-07-01 15:00:55.000000000 +0200 @@ -599,11 +599,7 @@ static void __enqueue_rt_entity(struct s if (group_rq && (rt_rq_throttled(group_rq) || !group_rq->rt_nr_running)) return; - if (rt_se->nr_cpus_allowed == 1) - list_add(&rt_se->run_list, queue); - else - list_add_tail(&rt_se->run_list, queue); - + list_add_tail(&rt_se->run_list, queue); __set_bit(rt_se_prio(rt_se), array->bitmap); inc_rt_tasks(rt_se, rt_rq); @@ -689,31 +685,33 @@ static void dequeue_task_rt(struct rq *r * followed by enqueue. */ static -void requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se) +void requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se, int head) { - struct rt_prio_array *array = &rt_rq->active; - if (on_rt_rq(rt_se)) { - list_del_init(&rt_se->run_list); - list_add_tail(&rt_se->run_list, - array->queue + rt_se_prio(rt_se)); + struct rt_prio_array *array = &rt_rq->active; + struct list_head *queue = array->queue + rt_se_prio(rt_se); + + if (head) + list_move(&rt_se->run_list, queue); + else + list_move_tail(&rt_se->run_list, queue); } } -static void requeue_task_rt(struct rq *rq, struct task_struct *p) +static void requeue_task_rt(struct rq *rq, struct task_struct *p, int head) { struct sched_rt_entity *rt_se = &p->rt; struct rt_rq *rt_rq; for_each_sched_rt_entity(rt_se) { rt_rq = rt_rq_of_se(rt_se); - requeue_rt_entity(rt_rq, rt_se); + requeue_rt_entity(rt_rq, rt_se, head); } } static void yield_task_rt(struct rq *rq) { - requeue_task_rt(rq, rq->curr); + requeue_task_rt(rq, rq->curr, 0); } #ifdef CONFIG_SMP @@ -753,6 +751,29 @@ static int select_task_rq_rt(struct task */ return task_cpu(p); } + +static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p) +{ + cpumask_t mask; + + if (rq->curr.rt.nr_cpus_allowed == 1 || p->rt.nr_cpus_allowed == 1) + return; + + if (cpupri_find(&rq->rd->cpupri, p, &mask)) + return; + + if (!cpupri_find(&rq->rd->cpupri, rq->curr, &mask)) + return; + + /* + * There appears to be other cpus that can accept + * current and none to run 'p', so lets reschedule + * to try and push current away: + */ + requeue_task_rt(rq, p, 1); + resched_task(rq->curr); +} + #endif /* CONFIG_SMP */ /* @@ -778,18 +799,8 @@ static void check_preempt_curr_rt(struct * to move current somewhere else, making room for our non-migratable * task. */ - if((p->prio == rq->curr->prio) - && p->rt.nr_cpus_allowed == 1 - && rq->curr->rt.nr_cpus_allowed != 1) { - cpumask_t mask; - - if (cpupri_find(&rq->rd->cpupri, rq->curr, &mask)) - /* - * There appears to be other cpus that can accept - * current, so lets reschedule to try and push it away - */ - resched_task(rq->curr); - } + if (p->prio == rq->curr->prio && !need_resched()) + check_preempt_equal_prio(rq, p); #endif } @@ -1415,7 +1426,7 @@ static void task_tick_rt(struct rq *rq, * on the queue: */ if (p->rt.run_list.prev != p->rt.run_list.next) { - requeue_task_rt(rq, p); + requeue_task_rt(rq, p, 0); set_tsk_need_resched(p); } } | |