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-rw-r--r--kernel/sched_fair.c32
1 files changed, 25 insertions, 7 deletions
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index ebd6de8..a6b1db8 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -341,9 +341,6 @@ static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
cfs_rq->rb_leftmost = next_node;
}
- if (cfs_rq->next == se)
- cfs_rq->next = NULL;
-
rb_erase(&se->run_node, &cfs_rq->tasks_timeline);
}
@@ -741,6 +738,12 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
#endif
}
+ if (cfs_rq->last == se)
+ cfs_rq->last = NULL;
+
+ if (cfs_rq->next == se)
+ cfs_rq->next = NULL;
+
if (se != cfs_rq->curr)
__dequeue_entity(cfs_rq, se);
account_entity_dequeue(cfs_rq, se);
@@ -798,10 +801,13 @@ static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq)
{
struct sched_entity *se = __pick_next_entity(cfs_rq);
- if (!cfs_rq->next || wakeup_preempt_entity(cfs_rq->next, se) == 1)
- return se;
+ if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, se) < 1)
+ return cfs_rq->next;
- return cfs_rq->next;
+ if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, se) < 1)
+ return cfs_rq->last;
+
+ return se;
}
static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
@@ -1319,10 +1325,11 @@ wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se)
static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int sync)
{
struct task_struct *curr = rq->curr;
- struct cfs_rq *cfs_rq = task_cfs_rq(curr);
struct sched_entity *se = &curr->se, *pse = &p->se;
if (unlikely(rt_prio(p->prio))) {
+ struct cfs_rq *cfs_rq = task_cfs_rq(curr);
+
update_rq_clock(rq);
update_curr(cfs_rq);
resched_task(curr);
@@ -1335,6 +1342,17 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int sync)
if (unlikely(se == pse))
return;
+ /*
+ * Only set the backward buddy when the current task is still on the
+ * rq. This can happen when a wakeup gets interleaved with schedule on
+ * the ->pre_schedule() or idle_balance() point, either of which can
+ * drop the rq lock.
+ *
+ * Also, during early boot the idle thread is in the fair class, for
+ * obvious reasons its a bad idea to schedule back to the idle thread.
+ */
+ if (sched_feat(LAST_BUDDY) && likely(se->on_rq && curr != rq->idle))
+ cfs_rq_of(se)->last = se;
cfs_rq_of(pse)->next = pse;
/*
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