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authorIngo Molnar <mingo@elte.hu>2008-05-29 11:28:57 +0200
committerIngo Molnar <mingo@elte.hu>2008-05-29 11:28:57 +0200
commit6363ca57c76b7b83639ca8c83fc285fa26a7880e (patch)
treeb8630b4af286409efdd648920a546fae24d4db88 /kernel/sched_fair.c
parent4285f594f84d1f0641fc962d00e6638dec4a19c4 (diff)
downloadblackbird-op-linux-6363ca57c76b7b83639ca8c83fc285fa26a7880e.tar.gz
blackbird-op-linux-6363ca57c76b7b83639ca8c83fc285fa26a7880e.zip
revert ("sched: fair-group: SMP-nice for group scheduling")
Yanmin Zhang reported: Comparing with 2.6.25, volanoMark has big regression with kernel 2.6.26-rc1. It's about 50% on my 8-core stoakley, 16-core tigerton, and Itanium Montecito. With bisect, I located the following patch: | 18d95a2832c1392a2d63227a7a6d433cb9f2037e is first bad commit | commit 18d95a2832c1392a2d63227a7a6d433cb9f2037e | Author: Peter Zijlstra <a.p.zijlstra@chello.nl> | Date: Sat Apr 19 19:45:00 2008 +0200 | | sched: fair-group: SMP-nice for group scheduling Revert it so that we get v2.6.25 behavior. Bisected-by: Yanmin Zhang <yanmin_zhang@linux.intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/sched_fair.c')
-rw-r--r--kernel/sched_fair.c124
1 files changed, 44 insertions, 80 deletions
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 0eb0ae879542..f0f25fc12d0a 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -510,27 +510,10 @@ update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
* Scheduling class queueing methods:
*/
-#if defined CONFIG_SMP && defined CONFIG_FAIR_GROUP_SCHED
-static void
-add_cfs_task_weight(struct cfs_rq *cfs_rq, unsigned long weight)
-{
- cfs_rq->task_weight += weight;
-}
-#else
-static inline void
-add_cfs_task_weight(struct cfs_rq *cfs_rq, unsigned long weight)
-{
-}
-#endif
-
static void
account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
update_load_add(&cfs_rq->load, se->load.weight);
- if (!parent_entity(se))
- inc_cpu_load(rq_of(cfs_rq), se->load.weight);
- if (entity_is_task(se))
- add_cfs_task_weight(cfs_rq, se->load.weight);
cfs_rq->nr_running++;
se->on_rq = 1;
list_add(&se->group_node, &cfs_rq->tasks);
@@ -540,10 +523,6 @@ static void
account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
update_load_sub(&cfs_rq->load, se->load.weight);
- if (!parent_entity(se))
- dec_cpu_load(rq_of(cfs_rq), se->load.weight);
- if (entity_is_task(se))
- add_cfs_task_weight(cfs_rq, -se->load.weight);
cfs_rq->nr_running--;
se->on_rq = 0;
list_del_init(&se->group_node);
@@ -1327,90 +1306,75 @@ static struct task_struct *load_balance_next_fair(void *arg)
return __load_balance_iterator(cfs_rq, cfs_rq->balance_iterator);
}
-static unsigned long
-__load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
- unsigned long max_load_move, struct sched_domain *sd,
- enum cpu_idle_type idle, int *all_pinned, int *this_best_prio,
- struct cfs_rq *cfs_rq)
+#ifdef CONFIG_FAIR_GROUP_SCHED
+static int cfs_rq_best_prio(struct cfs_rq *cfs_rq)
{
- struct rq_iterator cfs_rq_iterator;
+ struct sched_entity *curr;
+ struct task_struct *p;
- cfs_rq_iterator.start = load_balance_start_fair;
- cfs_rq_iterator.next = load_balance_next_fair;
- cfs_rq_iterator.arg = cfs_rq;
+ if (!cfs_rq->nr_running || !first_fair(cfs_rq))
+ return MAX_PRIO;
+
+ curr = cfs_rq->curr;
+ if (!curr)
+ curr = __pick_next_entity(cfs_rq);
- return balance_tasks(this_rq, this_cpu, busiest,
- max_load_move, sd, idle, all_pinned,
- this_best_prio, &cfs_rq_iterator);
+ p = task_of(curr);
+
+ return p->prio;
}
+#endif
-#ifdef CONFIG_FAIR_GROUP_SCHED
static unsigned long
load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
unsigned long max_load_move,
struct sched_domain *sd, enum cpu_idle_type idle,
int *all_pinned, int *this_best_prio)
{
+ struct cfs_rq *busy_cfs_rq;
long rem_load_move = max_load_move;
- int busiest_cpu = cpu_of(busiest);
- struct task_group *tg;
-
- rcu_read_lock();
- list_for_each_entry(tg, &task_groups, list) {
- long imbalance;
- unsigned long this_weight, busiest_weight;
- long rem_load, max_load, moved_load;
-
- /*
- * empty group
- */
- if (!aggregate(tg, sd)->task_weight)
- continue;
-
- rem_load = rem_load_move * aggregate(tg, sd)->rq_weight;
- rem_load /= aggregate(tg, sd)->load + 1;
-
- this_weight = tg->cfs_rq[this_cpu]->task_weight;
- busiest_weight = tg->cfs_rq[busiest_cpu]->task_weight;
+ struct rq_iterator cfs_rq_iterator;
- imbalance = (busiest_weight - this_weight) / 2;
+ cfs_rq_iterator.start = load_balance_start_fair;
+ cfs_rq_iterator.next = load_balance_next_fair;
- if (imbalance < 0)
- imbalance = busiest_weight;
+ for_each_leaf_cfs_rq(busiest, busy_cfs_rq) {
+#ifdef CONFIG_FAIR_GROUP_SCHED
+ struct cfs_rq *this_cfs_rq;
+ long imbalance;
+ unsigned long maxload;
- max_load = max(rem_load, imbalance);
- moved_load = __load_balance_fair(this_rq, this_cpu, busiest,
- max_load, sd, idle, all_pinned, this_best_prio,
- tg->cfs_rq[busiest_cpu]);
+ this_cfs_rq = cpu_cfs_rq(busy_cfs_rq, this_cpu);
- if (!moved_load)
+ imbalance = busy_cfs_rq->load.weight - this_cfs_rq->load.weight;
+ /* Don't pull if this_cfs_rq has more load than busy_cfs_rq */
+ if (imbalance <= 0)
continue;
- move_group_shares(tg, sd, busiest_cpu, this_cpu);
+ /* Don't pull more than imbalance/2 */
+ imbalance /= 2;
+ maxload = min(rem_load_move, imbalance);
- moved_load *= aggregate(tg, sd)->load;
- moved_load /= aggregate(tg, sd)->rq_weight + 1;
+ *this_best_prio = cfs_rq_best_prio(this_cfs_rq);
+#else
+# define maxload rem_load_move
+#endif
+ /*
+ * pass busy_cfs_rq argument into
+ * load_balance_[start|next]_fair iterators
+ */
+ cfs_rq_iterator.arg = busy_cfs_rq;
+ rem_load_move -= balance_tasks(this_rq, this_cpu, busiest,
+ maxload, sd, idle, all_pinned,
+ this_best_prio,
+ &cfs_rq_iterator);
- rem_load_move -= moved_load;
- if (rem_load_move < 0)
+ if (rem_load_move <= 0)
break;
}
- rcu_read_unlock();
return max_load_move - rem_load_move;
}
-#else
-static unsigned long
-load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
- unsigned long max_load_move,
- struct sched_domain *sd, enum cpu_idle_type idle,
- int *all_pinned, int *this_best_prio)
-{
- return __load_balance_fair(this_rq, this_cpu, busiest,
- max_load_move, sd, idle, all_pinned,
- this_best_prio, &busiest->cfs);
-}
-#endif
static int
move_one_task_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
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