sched: Fix wake_affine() vs RT tasks

Mike reports that since e9e9250b (sched: Scale down cpu_power due to RT
tasks), wake_affine() goes funny on RT tasks due to them still having a
!0 weight and wake_affine() still subtracts that from the rq weight.

Since nobody should be using se->weight for RT tasks, set the value to
zero. Also, since we now use ->cpu_power to normalize rq weights to
account for RT cpu usage, add that factor into the imbalance computation.

Reported-by: Mike Galbraith <efault@gmx.de>
Tested-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1275316109.27810.22969.camel@twins>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 6 insertions, 18 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index d48408142503..f8b8996228dd 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -544,6 +544,8 @@ struct rq {
         struct root_domain *rd;
         struct sched_domain *sd;
 
+        unsigned long cpu_power;
+
         unsigned char idle_at_tick;
         /* For active balancing */
         int post_schedule;
@@ -1499,24 +1501,9 @@ static unsigned long target_load(int cpu, int type)
         return max(rq->cpu_load[type-1], total);
 }
 
-static struct sched_group *group_of(int cpu)
-{
-        struct sched_domain *sd = rcu_dereference_sched(cpu_rq(cpu)->sd);
-
-        if (!sd)
-                return NULL;
-
-        return sd->groups;
-}
-
 static unsigned long power_of(int cpu)
 {
-        struct sched_group *group = group_of(cpu);
-
-        if (!group)
-                return SCHED_LOAD_SCALE;
-
-        return group->cpu_power;
+        return cpu_rq(cpu)->cpu_power;
 }
 
 static int task_hot(struct task_struct *p, u64 now, struct sched_domain *sd);
@@ -1854,8 +1841,8 @@ static void dec_nr_running(struct rq *rq)
 static void set_load_weight(struct task_struct *p)
 {
         if (task_has_rt_policy(p)) {
-                p->se.load.weight = prio_to_weight[0] * 2;
-                p->se.load.inv_weight = prio_to_wmult[0] >> 1;
+                p->se.load.weight = 0;
+                p->se.load.inv_weight = WMULT_CONST;
                 return;
         }
 
@@ -7605,6 +7592,7 @@ void __init sched_init(void)
 #ifdef CONFIG_SMP
                 rq->sd = NULL;
                 rq->rd = NULL;
+                rq->cpu_power = SCHED_LOAD_SCALE;
                 rq->post_schedule = 0;
                 rq->active_balance = 0;
                 rq->next_balance = jiffies;