This is an implementation of Steve's idea where we should update the RQ
concept of priority to show the highest-task, even if that task is not (yet)
running. This prevents us from pushing multiple tasks to the RQ before it
gets a chance to reschedule.
Signed-off-by: Gregory Haskins <[EMAIL PROTECTED]>
---
kernel/sched.c | 34 +++++++++++++++++++++++++---------
1 files changed, 25 insertions(+), 9 deletions(-)
diff --git a/kernel/sched.c b/kernel/sched.c
index 7c4fba8..c17e2e4 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -304,7 +304,7 @@ struct rq {
#ifdef CONFIG_PREEMPT_RT
unsigned long rt_nr_running;
unsigned long rt_nr_uninterruptible;
- int curr_prio;
+ int highest_prio;
#endif
unsigned long switch_timestamp;
@@ -368,11 +368,20 @@ static DEFINE_MUTEX(sched_hotcpu_mutex);
#if defined(CONFIG_PREEMPT_RT) && defined(CONFIG_SMP)
static inline void set_rq_prio(struct rq *rq, int prio)
{
- rq->curr_prio = prio;
+ rq->highest_prio = prio;
+}
+
+static inline void update_rq_prio(struct rq *rq)
+{
+ struct rt_prio_array *array = &rq->rt.active;
+ int prio = sched_find_first_bit(array->bitmap);
+
+ set_rq_prio(rq, prio);
}
#else
#define set_rq_prio(rq, prio) do { } while(0)
+#define update_rq_prio(rq) do { } while(0)
#endif
static inline void check_preempt_curr(struct rq *rq, struct task_struct *p)
@@ -1023,12 +1032,14 @@ static void enqueue_task(struct rq *rq, struct
task_struct *p, int wakeup)
sched_info_queued(p);
p->sched_class->enqueue_task(rq, p, wakeup);
p->se.on_rq = 1;
+ update_rq_prio(rq);
}
static void dequeue_task(struct rq *rq, struct task_struct *p, int sleep)
{
p->sched_class->dequeue_task(rq, p, sleep);
p->se.on_rq = 0;
+ update_rq_prio(rq);
}
/*
@@ -1526,15 +1537,15 @@ static struct rq *find_lock_lowest_rq(cpumask_t
*cpu_mask,
continue;
/* We look for lowest RT prio or non-rt CPU */
- if (rq->curr_prio >= MAX_RT_PRIO) {
+ if (rq->highest_prio >= MAX_RT_PRIO) {
lowest_rq = rq;
dst_cpu = cpu;
break;
}
/* no locking for now */
- if (rq->curr_prio > task->prio &&
- (!lowest_rq || rq->curr_prio <
lowest_rq->curr_prio)) {
+ if (rq->highest_prio > task->prio &&
+ (!lowest_rq || rq->highest_prio <
lowest_rq->highest_prio)) {
lowest_rq = rq;
dst_cpu = cpu;
}
@@ -1560,7 +1571,7 @@ static struct rq *find_lock_lowest_rq(cpumask_t *cpu_mask,
}
/* If this rq is still suitable use it. */
- if (lowest_rq->curr_prio > task->prio)
+ if (lowest_rq->highest_prio > task->prio)
break;
/* try again */
@@ -2339,10 +2350,8 @@ static inline void finish_task_switch(struct rq *rq,
struct task_struct *prev)
*/
prev_state = prev->state;
_finish_arch_switch(prev);
-
- set_rq_prio(rq, current->prio);
-
finish_lock_switch(rq, prev);
+
#if defined(CONFIG_PREEMPT_RT) && defined(CONFIG_SMP)
/*
* If we pushed an RT task off the runqueue,
@@ -4647,6 +4656,9 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
prev_resched = _need_resched();
if (on_rq) {
+ /*
+ * Note: RQ priority gets updated in the enqueue/dequeue logic
+ */
enqueue_task(rq, p, 0);
/*
* Reschedule if we are currently running on this runqueue and
@@ -4713,6 +4725,10 @@ void set_user_nice(struct task_struct *p, long nice)
*/
if (delta < 0 || (delta > 0 && task_running(rq, p)))
resched_task(rq->curr);
+
+ /*
+ * Note: RQ priority gets updated in the enqueue/dequeue logic
+ */
}
out_unlock:
task_rq_unlock(rq, &flags);
-
To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
