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sched: Fix wake_affine() vs RT tasks

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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>
This commit is contained in:
Peter Zijlstra
2010-05-31 12:37:30 +02:00
committed by Ingo Molnar
parent 54e88fad22
commit e51fd5e22e
2 changed files with 22 additions and 24 deletions
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22
kernel/sched_fair.c
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@@ -1225,7 +1225,6 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
unsigned long this_load, load;
int idx, this_cpu, prev_cpu;
unsigned long tl_per_task;
unsigned int imbalance;
struct task_group *tg;
unsigned long weight;
int balanced;
@@ -1252,8 +1251,6 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
tg = task_group(p);
weight = p->se.load.weight;
imbalance = 100 + (sd->imbalance_pct - 100) / 2;
/*
* In low-load situations, where prev_cpu is idle and this_cpu is idle
* due to the sync cause above having dropped this_load to 0, we'll
@@ -1263,9 +1260,21 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
* Otherwise check if either cpus are near enough in load to allow this
* task to be woken on this_cpu.
*/
balanced = !this_load ||
100*(this_load + effective_load(tg, this_cpu, weight, weight)) <=
imbalance*(load + effective_load(tg, prev_cpu, 0, weight));
if (this_load) {
unsigned long this_eff_load, prev_eff_load;
this_eff_load = 100;
this_eff_load *= power_of(prev_cpu);
this_eff_load *= this_load +
effective_load(tg, this_cpu, weight, weight);
prev_eff_load = 100 + (sd->imbalance_pct - 100) / 2;
prev_eff_load *= power_of(this_cpu);
prev_eff_load *= load + effective_load(tg, prev_cpu, 0, weight);
balanced = this_eff_load <= prev_eff_load;
} else
balanced = true;
/*
* If the currently running task will sleep within
@@ -2298,6 +2307,7 @@ static void update_cpu_power(struct sched_domain *sd, int cpu)
if (!power)
power = 1;
cpu_rq(cpu)->cpu_power = power;
sdg->cpu_power = power;
}