On 25/03/15 23:50, Sai Gurrappadi wrote:
> On 02/04/2015 10:31 AM, Morten Rasmussen wrote:
>> From: Dietmar Eggemann <dietmar.eggem...@arm.com>
>> while (!list_empty(tasks)) {
>> @@ -6121,6 +6121,20 @@ static int detach_tasks(struct lb_env *env)
>> if (!can_migrate_task(p, env))
>> goto next;
>>
>> + if (env->use_ea) {
>> + struct energy_env eenv = {
>> + .src_cpu = env->src_cpu,
>> + .dst_cpu = env->dst_cpu,
>> + .usage_delta = task_utilization(p),
>> + };
>> + int e_diff = energy_diff(&eenv);
>> +
>> + if (e_diff >= 0)
>> + goto next;
>> +
>> + goto detach;
>> + }
>> +
>> load = task_h_load(p);
>>
>> if (sched_feat(LB_MIN) && load < 16 &&
>> !env->sd->nr_balance_failed)
>> @@ -6129,6 +6143,7 @@ static int detach_tasks(struct lb_env *env)
>> if ((load / 2) > env->imbalance)
>> goto next;
>>
>> +detach:
>> detach_task(p, env);
>> list_add(&p->se.group_node, &env->tasks);
>
> Hi Morten, Dietmar,
>
> Wouldn't the above energy_diff() use the 'old' value of dst_cpu's util?
> Tasks are detached/dequeued in this loop so they have their util
> contrib. removed from src_cpu but their contrib. hasn't been added to
> dst_cpu yet (happens in attach_tasks).
You're absolutely right Sai. Thanks for pointing this out! I guess I rather
have to accumulate the usage of tasks I've detached and add this to the
eenv::usage_delta of the energy_diff() call for the next task.
Something like this (only slightly tested):
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 8d4cc72f4778..d0d0e965fd0c 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6097,6 +6097,7 @@ static int detach_tasks(struct lb_env *env)
struct task_struct *p;
unsigned long load = 0;
int detached = 0;
+ int usage_delta = 0;
lockdep_assert_held(&env->src_rq->lock);
@@ -6122,16 +6123,19 @@ static int detach_tasks(struct lb_env *env)
goto next;
if (env->use_ea) {
+ int util = task_utilization(p);
struct energy_env eenv = {
.src_cpu = env->src_cpu,
.dst_cpu = env->dst_cpu,
- .usage_delta = task_utilization(p),
+ .usage_delta = usage_delta + util,
};
int e_diff = energy_diff(&eenv);
if (e_diff >= 0)
goto next;
+ usage_delta += util;
+
goto detach;
}
[...]
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