sched: Update tg->shares after cpu.shares write

Formerly sched_group_set_shares would force a rebalance by overflowing domain
share sums.  Now that per-cpu averages are maintained we can set the true value
by issuing an update_cfs_shares() following a tg->shares update.

Also initialize tg se->load to 0 for consistency since we'll now set correct
weights on enqueue.

Signed-off-by: Paul Turner <pjt@google.com?>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20101115234938.465521344@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/sched.c b/kernel/sched.c
index e914a71..550cf3a 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -7646,7 +7646,7 @@ static void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq,
                se->cfs_rq = parent->my_q;
 
        se->my_q = cfs_rq;
-       update_load_set(&se->load, tg->shares);
+       update_load_set(&se->load, 0);
        se->parent = parent;
 }
 #endif
@@ -8274,37 +8274,12 @@ void sched_move_task(struct task_struct *tsk)
 #endif /* CONFIG_CGROUP_SCHED */
 
 #ifdef CONFIG_FAIR_GROUP_SCHED
-static void __set_se_shares(struct sched_entity *se, unsigned long shares)
-{
-       struct cfs_rq *cfs_rq = se->cfs_rq;
-       int on_rq;
-
-       on_rq = se->on_rq;
-       if (on_rq)
-               dequeue_entity(cfs_rq, se, 0);
-
-       update_load_set(&se->load, shares);
-
-       if (on_rq)
-               enqueue_entity(cfs_rq, se, 0);
-}
-
-static void set_se_shares(struct sched_entity *se, unsigned long shares)
-{
-       struct cfs_rq *cfs_rq = se->cfs_rq;
-       struct rq *rq = cfs_rq->rq;
-       unsigned long flags;
-
-       raw_spin_lock_irqsave(&rq->lock, flags);
-       __set_se_shares(se, shares);
-       raw_spin_unlock_irqrestore(&rq->lock, flags);
-}
-
 static DEFINE_MUTEX(shares_mutex);
 
 int sched_group_set_shares(struct task_group *tg, unsigned long shares)
 {
        int i;
+       unsigned long flags;
 
        /*
         * We can't change the weight of the root cgroup.
@@ -8323,10 +8298,15 @@ int sched_group_set_shares(struct task_group *tg, unsigned long shares)
 
        tg->shares = shares;
        for_each_possible_cpu(i) {
-               /*
-                * force a rebalance
-                */
-               set_se_shares(tg->se[i], shares);
+               struct rq *rq = cpu_rq(i);
+               struct sched_entity *se;
+
+               se = tg->se[i];
+               /* Propagate contribution to hierarchy */
+               raw_spin_lock_irqsave(&rq->lock, flags);
+               for_each_sched_entity(se)
+                       update_cfs_shares(group_cfs_rq(se), 0);
+               raw_spin_unlock_irqrestore(&rq->lock, flags);
        }
 
 done: