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authorDavid S. Miller <davem@davemloft.net>2009-11-19 01:19:03 -0500
committerDavid S. Miller <davem@davemloft.net>2009-11-19 01:19:03 -0500
commit3505d1a9fd65e2d3e00827857b6795d9d8983658 (patch)
tree941cfafdb57c427bb6b7ebf6354ee93b2a3693b5 /kernel/sched_fair.c
parentdfef948ed2ba69cf041840b5e860d6b4e16fa0b1 (diff)
parent66b00a7c93ec782d118d2c03bd599cfd041e80a1 (diff)
Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6
Conflicts: drivers/net/sfc/sfe4001.c drivers/net/wireless/libertas/cmd.c drivers/staging/Kconfig drivers/staging/Makefile drivers/staging/rtl8187se/Kconfig drivers/staging/rtl8192e/Kconfig
Diffstat (limited to 'kernel/sched_fair.c')
-rw-r--r--kernel/sched_fair.c74
1 files changed, 47 insertions, 27 deletions
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 4e777b47eeda..37087a7fac22 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -822,6 +822,26 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
822 * re-elected due to buddy favours. 822 * re-elected due to buddy favours.
823 */ 823 */
824 clear_buddies(cfs_rq, curr); 824 clear_buddies(cfs_rq, curr);
825 return;
826 }
827
828 /*
829 * Ensure that a task that missed wakeup preemption by a
830 * narrow margin doesn't have to wait for a full slice.
831 * This also mitigates buddy induced latencies under load.
832 */
833 if (!sched_feat(WAKEUP_PREEMPT))
834 return;
835
836 if (delta_exec < sysctl_sched_min_granularity)
837 return;
838
839 if (cfs_rq->nr_running > 1) {
840 struct sched_entity *se = __pick_next_entity(cfs_rq);
841 s64 delta = curr->vruntime - se->vruntime;
842
843 if (delta > ideal_runtime)
844 resched_task(rq_of(cfs_rq)->curr);
825 } 845 }
826} 846}
827 847
@@ -861,12 +881,18 @@ wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se);
861static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq) 881static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq)
862{ 882{
863 struct sched_entity *se = __pick_next_entity(cfs_rq); 883 struct sched_entity *se = __pick_next_entity(cfs_rq);
884 struct sched_entity *left = se;
864 885
865 if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, se) < 1) 886 if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1)
866 return cfs_rq->next; 887 se = cfs_rq->next;
867 888
868 if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, se) < 1) 889 /*
869 return cfs_rq->last; 890 * Prefer last buddy, try to return the CPU to a preempted task.
891 */
892 if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1)
893 se = cfs_rq->last;
894
895 clear_buddies(cfs_rq, se);
870 896
871 return se; 897 return se;
872} 898}
@@ -1568,6 +1594,7 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_
1568 struct sched_entity *se = &curr->se, *pse = &p->se; 1594 struct sched_entity *se = &curr->se, *pse = &p->se;
1569 struct cfs_rq *cfs_rq = task_cfs_rq(curr); 1595 struct cfs_rq *cfs_rq = task_cfs_rq(curr);
1570 int sync = wake_flags & WF_SYNC; 1596 int sync = wake_flags & WF_SYNC;
1597 int scale = cfs_rq->nr_running >= sched_nr_latency;
1571 1598
1572 update_curr(cfs_rq); 1599 update_curr(cfs_rq);
1573 1600
@@ -1582,18 +1609,7 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_
1582 if (unlikely(se == pse)) 1609 if (unlikely(se == pse))
1583 return; 1610 return;
1584 1611
1585 /* 1612 if (sched_feat(NEXT_BUDDY) && scale && !(wake_flags & WF_FORK))
1586 * Only set the backward buddy when the current task is still on the
1587 * rq. This can happen when a wakeup gets interleaved with schedule on
1588 * the ->pre_schedule() or idle_balance() point, either of which can
1589 * drop the rq lock.
1590 *
1591 * Also, during early boot the idle thread is in the fair class, for
1592 * obvious reasons its a bad idea to schedule back to the idle thread.
1593 */
1594 if (sched_feat(LAST_BUDDY) && likely(se->on_rq && curr != rq->idle))
1595 set_last_buddy(se);
1596 if (sched_feat(NEXT_BUDDY) && !(wake_flags & WF_FORK))
1597 set_next_buddy(pse); 1613 set_next_buddy(pse);
1598 1614
1599 /* 1615 /*
@@ -1639,8 +1655,22 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_
1639 1655
1640 BUG_ON(!pse); 1656 BUG_ON(!pse);
1641 1657
1642 if (wakeup_preempt_entity(se, pse) == 1) 1658 if (wakeup_preempt_entity(se, pse) == 1) {
1643 resched_task(curr); 1659 resched_task(curr);
1660 /*
1661 * Only set the backward buddy when the current task is still
1662 * on the rq. This can happen when a wakeup gets interleaved
1663 * with schedule on the ->pre_schedule() or idle_balance()
1664 * point, either of which can * drop the rq lock.
1665 *
1666 * Also, during early boot the idle thread is in the fair class,
1667 * for obvious reasons its a bad idea to schedule back to it.
1668 */
1669 if (unlikely(!se->on_rq || curr == rq->idle))
1670 return;
1671 if (sched_feat(LAST_BUDDY) && scale && entity_is_task(se))
1672 set_last_buddy(se);
1673 }
1644} 1674}
1645 1675
1646static struct task_struct *pick_next_task_fair(struct rq *rq) 1676static struct task_struct *pick_next_task_fair(struct rq *rq)
@@ -1654,16 +1684,6 @@ static struct task_struct *pick_next_task_fair(struct rq *rq)
1654 1684
1655 do { 1685 do {
1656 se = pick_next_entity(cfs_rq); 1686 se = pick_next_entity(cfs_rq);
1657 /*
1658 * If se was a buddy, clear it so that it will have to earn
1659 * the favour again.
1660 *
1661 * If se was not a buddy, clear the buddies because neither
1662 * was elegible to run, let them earn it again.
1663 *
1664 * IOW. unconditionally clear buddies.
1665 */
1666 __clear_buddies(cfs_rq, NULL);
1667 set_next_entity(cfs_rq, se); 1687 set_next_entity(cfs_rq, se);
1668 cfs_rq = group_cfs_rq(se); 1688 cfs_rq = group_cfs_rq(se);
1669 } while (cfs_rq); 1689 } while (cfs_rq);