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SubjectRe: [PATCH v4 1/2] block, bfq: counted root group into 'num_groups_with_pending_reqs'
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On 2021/10/20 17:43, Paolo Valente wrote:
>
>
>> Il giorno 20 ott 2021, alle ore 11:38, yukuai (C) <yukuai3@huawei.com> ha scritto:
>>
>> On 2021/10/20 17:29, Paolo Valente wrote:
>>>> Il giorno 20 ott 2021, alle ore 11:20, yukuai (C) <yukuai3@huawei.com> ha scritto:
>>>>
>>>> On 2021/10/20 16:51, Paolo Valente wrote:
>>>>
>>>>>> @@ -860,9 +870,25 @@ void bfq_weights_tree_remove(struct bfq_data *bfqd,
>>>>>> struct bfq_queue *bfqq)
>>>>>> {
>>>>>> struct bfq_entity *entity = bfqq->entity.parent;
>>>>>> + struct bfq_sched_data *sd;
>>>>>> +
>>>>>> + /*
>>>>>> + * If the bfq queue is in root group, the decrement of
>>>>>> + * num_groups_with_pending_reqs is performed immediately upon the
>>>>>> + * deactivation of entity.
>>>>>> + */
>>>>>> + if (!entity) {
>>>>>> + entity = &bfqd->root_group->entity;
>>>>>> + sd = entity->my_sched_data;
>>>>>> +
>>>>>> + if (!sd->in_service_entity)
>>>>>> + bfq_clear_group_with_pending_reqs(bfqd, entity);
>>>>>> +
>>>>>> + return;
>>>>>> + }
>>>>>>
>>>>>> for_each_entity(entity) {
>>>>>> - struct bfq_sched_data *sd = entity->my_sched_data;
>>>>>> + sd = entity->my_sched_data;
>>>>>>
>>>>>> if (sd->next_in_service || sd->in_service_entity) {
>>>>>> /*
>>>>>> @@ -880,7 +906,8 @@ void bfq_weights_tree_remove(struct bfq_data *bfqd,
>>>>>> }
>>>>>>
>>>>>> /*
>>>>>> - * The decrement of num_groups_with_pending_reqs is
>>>>>> + * If the bfq queue is not in root group,
>>>>>> + * the decrement of num_groups_with_pending_reqs is
>>>>> I'm sorry if I didn't notice this before, but why do you postpone the
>>>>> decrement only for queues not in root group? If I'm not missing
>>>>> anything, the active (i.e., with pending reqs) state of the root group
>>>>> is to be computed as that of ay other group.
>>>>
>>>> Hi, Paolo
>>>>
>>>> I thought if queue is in root group, then bfqq->entity.parent is NULL,
>>>> and such case is handled above, which is separate from previous
>>>> implementation for queues that are not in root group.
>>>>
>>>> Is this the wrong way to handle root group?
>>>>
>>> I think that, if we want to count also the root group among the active
>>> ones, then the logic for tagging the root group as active must be the
>>> same as the other groups. Or am I missing something?
>>
>> Hi, Paolo
>>
>> Currently, if queue is in root group, bfqq->entity.parent is NULL, and
>> this makes it hard to keep the same logic.
>>
>> Can we store root_group->my_entity to bfqq->entity.parent if the queue
>> is in root group?
>>
>
> Any sensible implementation is ok for me. Usually, stuff for root
> group is in the bfqd.
>

I'll try to do implement that way,

Thanks,
Kuai

> Thanks,
> Paolo
>
>> Thanks,
>> Kuai
>
> .
>

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