On 21 October 2016 at 14:19, Dietmar Eggemann <[email protected]> wrote:
>
> On 10/17/2016 10:14 AM, Vincent Guittot wrote:
>>
>> When a task moves from/to a cfs_rq, we set a flag which is then used to
>> propagate the change at parent level (sched_entity and cfs_rq) during
>> next update. If the cfs_rq is throttled, the flag will stay pending until
>> the cfs_rw is unthrottled.
>
>
> minor nit:
>
> s/cfs_rw/cfs_rq
yes
>
> [...]
>
>
>> @@ -8704,6 +8867,22 @@ static void detach_task_cfs_rq(struct task_struct *p)
>> update_load_avg(se, 0);
>> detach_entity_load_avg(cfs_rq, se);
>> update_tg_load_avg(cfs_rq, false);
>> +
>> +#ifdef CONFIG_FAIR_GROUP_SCHED
>> + /*
>> + * Propagate the detach across the tg tree to make it visible to the
>> + * root
>> + */
>> + se = se->parent;
>> + for_each_sched_entity(se) {
>> + cfs_rq = cfs_rq_of(se);
>> +
>> + if (cfs_rq_throttled(cfs_rq))
>> + break;
>> +
>> + update_load_avg(se, UPDATE_TG);
>> + }
>> +#endif
>> }
>>
>> static void attach_entity_cfs_rq(struct sched_entity *se)
>> @@ -8722,6 +8901,22 @@ static void attach_entity_cfs_rq(struct sched_entity
>> *se)
>> update_load_avg(se, sched_feat(ATTACH_AGE_LOAD) ? 0 : SKIP_AGE_LOAD);
>> attach_entity_load_avg(cfs_rq, se);
>> update_tg_load_avg(cfs_rq, false);
>> +
>> +#ifdef CONFIG_FAIR_GROUP_SCHED
>> + /*
>> + * Propagate the attach across the tg tree to make it visible to the
>> + * root
>> + */
>> + se = se->parent;
>> + for_each_sched_entity(se) {
>> + cfs_rq = cfs_rq_of(se);
>> +
>> + if (cfs_rq_throttled(cfs_rq))
>> + break;
>> +
>> + update_load_avg(se, UPDATE_TG);
>> + }
>> +#endif
>> }
>
>
> The 'detach across' and 'attach across' in detach_task_cfs_rq() and
> attach_entity_cfs_rq() do the same so couldn't you not create a function
> propagate_foo() for it? This would avoid this ifdef as well.
>
> You could further create in your '[PATCH 1/6 v5] sched: factorize attach
> entity':
>
> detach_entity_cfs_rq() {
> update_load_avg()
> detach_entity_load_avg()
> update_tg_load_avg()
> propagate_load_avg()
> }
>
> and then we would have:
>
> attach_task_cfs_rq() -> attach_entity_cfs_rq() -> propagate_foo()
> detach_task_cfs_rq() -> detach_entity_cfs_rq() -> propagate_foo()
>
> I guess you didn't because it would be only called one time but this
> symmetric approaches are easier to remember (at least for me).
Yes i haven't created attach_entity_cfs_rq because it would be used only once.
Regarding the creation of a propagate_foo function, i have just
followed a similar skeleton as what is done in
enqueue/dequeue_task_fair
I don't have strong opinion about creating this indirection for code
readability. Others, have you got a preference ?
>
> [...]
