[RFC tg_shares_up improvements - v1 11/12] sched: update tg->shares after cpu.shares write

pjt
2010-10-16T04:55:34Z

[-- Attachment #1: sched-tg-fix_group_set_shares.patch --]
[-- Type: text/plain, Size: 2279 bytes --]

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?>

---
kernel/sched.c | 42 +++++++++++-------------------------------
1 file changed, 11 insertions(+), 31 deletions(-)

Index: kernel/sched.c
===================================================================
--- kernel/sched.c.orig
+++ kernel/sched.c
@@ -7575,7 +7575,7 @@ static void init_tg_cfs_entry(struct tas
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
@@ -8194,37 +8194,12 @@ void sched_move_task(struct task_struct
#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.
@@ -8243,10 +8218,15 @@ int sched_group_set_shares(struct task_g

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:

--