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authorLinus Torvalds <torvalds@linux-foundation.org>2008-11-06 15:45:40 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2008-11-06 15:45:40 -0800
commit067ab19923673e3d8c982d877bedb9d65c976c22 (patch)
treeb11c20e4b5a6671355924b656f9348d4ece5523f /kernel/sched_fair.c
parent7597bc94d6f3bdccb086ac7f2ad91292fdaee2a4 (diff)
parent9fcd18c9e63e325dbd2b4c726623f760788d5aa8 (diff)
downloadlinux-2.6.38-lt-ux500-067ab19923673e3d8c982d877bedb9d65c976c22.tar.gz
Merge branch 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: sched: re-tune balancing sched: fix buddies for group scheduling sched: backward looking buddy sched: fix fair preempt check sched: cleanup fair task selection
Diffstat (limited to 'kernel/sched_fair.c')
-rw-r--r--kernel/sched_fair.c76
1 files changed, 49 insertions, 27 deletions
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index ce514afd78f..51aa3e102ac 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -341,23 +341,20 @@ 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);
}
-static inline struct rb_node *first_fair(struct cfs_rq *cfs_rq)
-{
- return cfs_rq->rb_leftmost;
-}
-
static struct sched_entity *__pick_next_entity(struct cfs_rq *cfs_rq)
{
- return rb_entry(first_fair(cfs_rq), struct sched_entity, run_node);
+ struct rb_node *left = cfs_rq->rb_leftmost;
+
+ if (!left)
+ return NULL;
+
+ return rb_entry(left, struct sched_entity, run_node);
}
-static inline struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
+static struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
{
struct rb_node *last = rb_last(&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);
@@ -794,24 +797,15 @@ set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
static int
wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se);
-static struct sched_entity *
-pick_next(struct cfs_rq *cfs_rq, struct sched_entity *se)
-{
- if (!cfs_rq->next || wakeup_preempt_entity(cfs_rq->next, se) == 1)
- return se;
-
- return cfs_rq->next;
-}
-
static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq)
{
- struct sched_entity *se = NULL;
+ struct sched_entity *se = __pick_next_entity(cfs_rq);
- if (first_fair(cfs_rq)) {
- se = __pick_next_entity(cfs_rq);
- se = pick_next(cfs_rq, se);
- set_next_entity(cfs_rq, se);
- }
+ if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, se) < 1)
+ return cfs_rq->next;
+
+ if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, se) < 1)
+ return cfs_rq->last;
return se;
}
@@ -1325,26 +1319,53 @@ wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se)
return 0;
}
+static void set_last_buddy(struct sched_entity *se)
+{
+ for_each_sched_entity(se)
+ cfs_rq_of(se)->last = se;
+}
+
+static void set_next_buddy(struct sched_entity *se)
+{
+ for_each_sched_entity(se)
+ cfs_rq_of(se)->next = se;
+}
+
/*
* Preempt the current task with a newly woken task if needed:
*/
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);
return;
}
+ if (unlikely(p->sched_class != &fair_sched_class))
+ return;
+
if (unlikely(se == pse))
return;
- cfs_rq_of(pse)->next = pse;
+ /*
+ * 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))
+ set_last_buddy(se);
+ set_next_buddy(pse);
/*
* We can come here with TIF_NEED_RESCHED already set from new task
@@ -1396,6 +1417,7 @@ static struct task_struct *pick_next_task_fair(struct rq *rq)
do {
se = pick_next_entity(cfs_rq);
+ set_next_entity(cfs_rq, se);
cfs_rq = group_cfs_rq(se);
} while (cfs_rq);