Re: [PATCH V2] sched/fair: Fix that tasks are not constrained by cfs_b->quota on hotplug core, when hotplug core is offline and then online.

[bsegall]

Jeehong Kim  writes:

> On 2016년 09월 23일 01:53, bseg...@google.com wrote:
>> Jeehong Kim  writes:
>>
 Peter Zijlstra  writes:

> You forgot to Cc Ben, who gave you feedback on v1, which is rather poor
> style. Also, I don't see how kernel-janitors is relevant to this patch.
> This is very much not a janitorial thing.
>
> (also, why send it twice?)
>
> On Tue, Aug 30, 2016 at 10:12:40PM +0900, Jeehong Kim wrote:
>> In case that CONFIG_HOTPLUG_CPU and CONFIG_CFS_BANDWIDTH is turned on
>> and tasks in bandwidth controlled task group run on hotplug core,
>> the tasks are not controlled by cfs_b->quota when hotplug core is offline
>> and then online. The remaining tasks in task group consume all of
>> cfs_b->quota on other cores.
>>
>> The cause of this problem is described as below:
>>
>> 1. When hotplug core is offline while tasks in task group run
>> on hotplug core, unregister_fair_sched_group() deletes
>> leaf_cfs_rq_list of tg->cfs_rq[cpu] from 
>> _of(cfs_rq)->leaf_cfs_rq_list.
>>
>> 2. Then, when hotplug core is online, update_runtime_enabled()
> Peter Zijlstra  writes:
> You forgot to Cc Ben, who gave you feedback on v1, which is rather poor
> style. Also, I don't see how kernel-janitors is relevant to this patch.
> This is very much not a janitorial thing.
>
> (also, why send it twice?)
>
> On Tue, Aug 30, 2016 at 10:12:40PM +0900, Jeehong Kim wrote:
>> In case that CONFIG_HOTPLUG_CPU and CONFIG_CFS_BANDWIDTH is turned on
>> and tasks in bandwidth controlled task group run on hotplug core,
>> the tasks are not controlled by cfs_b->quota when hotplug core is offline
>> and then online. The remaining tasks in task group consume all of
>> cfs_b->quota on other cores.
>>
>> The cause of this problem is described as below:
>>
>> 1. When hotplug core is offline while tasks in task group run
>> on hotplug core, unregister_fair_sched_group() deletes
>> leaf_cfs_rq_list of tg->cfs_rq[cpu] from 
>> _of(cfs_rq)->leaf_cfs_rq_list.
>>
>> 2. Then, when hotplug core is online, update_runtime_enabled()
>> registers cfs_b->quota on cfs_rq->runtime_enabled of all leaf cfs_rq
>> on runqueue. However, because this is before enqueue_entity() adds
>> _rq->leaf_cfs_rq_list on _of(cfs_rq)->leaf_cfs_rq_list,
>> cfs->quota is not register on cfs_rq->runtime_enabled.
>>
>> To resolve this problem, this patch makes update_runtime_enabled()
>> registers cfs_b->quota by using walk_tg_tree_from().
>
>> +static int __maybe_unused __update_runtime_enabled(struct task_group 
>> *tg, void *data)
>>  {
>> +struct rq *rq = data;
>> +struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
>> +struct cfs_bandwidth *cfs_b = _rq->tg->cfs_bandwidth;
>>
>> +raw_spin_lock(_b->lock);
>> +raw_spin_unlock(_b->lock);
>>
>> +return 0;
>> +}
>> +
>> +static void __maybe_unused update_runtime_enabled(struct rq *rq)
>> +{
>> +struct cfs_rq *cfs_rq = >cfs;
>> +
>> +/* register cfs_b->quota on the whole tg tree */
>> +rcu_read_lock();
>> +walk_tg_tree_from(cfs_rq->tg, __update_runtime_enabled, tg_nop, 
>> (void *)rq);
>> +rcu_read_unlock();
>>  }
> Looks ok, performance on hotplug doesn't really matter. Ben, you happy
> with this?
 I'm not 100% sure about the exact timings and mechanics of hotplug, but
 cfs-bandwidth wise this is ok. We may still have runtime_remaining = 1,
 or we may have < 0 and yet be unthrottled, but either case is ok, even
 if hotplug allows tasks to have migrated here already (I'm not sure,
 looking at the code).

 Now that I check again you can just loop over the list of tgs rather
 than the hierarchical walk_tg_tree_from, but there's certainly no harm
 in it.
>>> Ben,
>>>
>>> Is there additional revision which I have to do?
>>> If so, could you let me know about that?
>>>
>>> Regards,
>>> Jeehong Kim
>> Oh, no, this is fine by me.
>>
>>
>>
>
> Ben,
>
> If this is fine to you, could you sign off on this patch?
>
> Regards,
> Jeehong Kim.

Reviewed-By: Ben Segall 

(My understanding of signed-off-by is that I don't do that in this case)

Re: [PATCH V2] sched/fair: Fix that tasks are not constrained by cfs_b->quota on hotplug core, when hotplug core is offline and then online.

[bsegall]

Jeehong Kim  writes:

> On 2016년 09월 23일 01:53, bseg...@google.com wrote:
>> Jeehong Kim  writes:
>>
 Peter Zijlstra  writes:

> You forgot to Cc Ben, who gave you feedback on v1, which is rather poor
> style. Also, I don't see how kernel-janitors is relevant to this patch.
> This is very much not a janitorial thing.
>
> (also, why send it twice?)
>
> On Tue, Aug 30, 2016 at 10:12:40PM +0900, Jeehong Kim wrote:
>> In case that CONFIG_HOTPLUG_CPU and CONFIG_CFS_BANDWIDTH is turned on
>> and tasks in bandwidth controlled task group run on hotplug core,
>> the tasks are not controlled by cfs_b->quota when hotplug core is offline
>> and then online. The remaining tasks in task group consume all of
>> cfs_b->quota on other cores.
>>
>> The cause of this problem is described as below:
>>
>> 1. When hotplug core is offline while tasks in task group run
>> on hotplug core, unregister_fair_sched_group() deletes
>> leaf_cfs_rq_list of tg->cfs_rq[cpu] from 
>> _of(cfs_rq)->leaf_cfs_rq_list.
>>
>> 2. Then, when hotplug core is online, update_runtime_enabled()
> Peter Zijlstra  writes:
> You forgot to Cc Ben, who gave you feedback on v1, which is rather poor
> style. Also, I don't see how kernel-janitors is relevant to this patch.
> This is very much not a janitorial thing.
>
> (also, why send it twice?)
>
> On Tue, Aug 30, 2016 at 10:12:40PM +0900, Jeehong Kim wrote:
>> In case that CONFIG_HOTPLUG_CPU and CONFIG_CFS_BANDWIDTH is turned on
>> and tasks in bandwidth controlled task group run on hotplug core,
>> the tasks are not controlled by cfs_b->quota when hotplug core is offline
>> and then online. The remaining tasks in task group consume all of
>> cfs_b->quota on other cores.
>>
>> The cause of this problem is described as below:
>>
>> 1. When hotplug core is offline while tasks in task group run
>> on hotplug core, unregister_fair_sched_group() deletes
>> leaf_cfs_rq_list of tg->cfs_rq[cpu] from 
>> _of(cfs_rq)->leaf_cfs_rq_list.
>>
>> 2. Then, when hotplug core is online, update_runtime_enabled()
>> registers cfs_b->quota on cfs_rq->runtime_enabled of all leaf cfs_rq
>> on runqueue. However, because this is before enqueue_entity() adds
>> _rq->leaf_cfs_rq_list on _of(cfs_rq)->leaf_cfs_rq_list,
>> cfs->quota is not register on cfs_rq->runtime_enabled.
>>
>> To resolve this problem, this patch makes update_runtime_enabled()
>> registers cfs_b->quota by using walk_tg_tree_from().
>
>> +static int __maybe_unused __update_runtime_enabled(struct task_group 
>> *tg, void *data)
>>  {
>> +struct rq *rq = data;
>> +struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
>> +struct cfs_bandwidth *cfs_b = _rq->tg->cfs_bandwidth;
>>
>> +raw_spin_lock(_b->lock);
>> +raw_spin_unlock(_b->lock);
>>
>> +return 0;
>> +}
>> +
>> +static void __maybe_unused update_runtime_enabled(struct rq *rq)
>> +{
>> +struct cfs_rq *cfs_rq = >cfs;
>> +
>> +/* register cfs_b->quota on the whole tg tree */
>> +rcu_read_lock();
>> +walk_tg_tree_from(cfs_rq->tg, __update_runtime_enabled, tg_nop, 
>> (void *)rq);
>> +rcu_read_unlock();
>>  }
> Looks ok, performance on hotplug doesn't really matter. Ben, you happy
> with this?
 I'm not 100% sure about the exact timings and mechanics of hotplug, but
 cfs-bandwidth wise this is ok. We may still have runtime_remaining = 1,
 or we may have < 0 and yet be unthrottled, but either case is ok, even
 if hotplug allows tasks to have migrated here already (I'm not sure,
 looking at the code).

 Now that I check again you can just loop over the list of tgs rather
 than the hierarchical walk_tg_tree_from, but there's certainly no harm
 in it.
>>> Ben,
>>>
>>> Is there additional revision which I have to do?
>>> If so, could you let me know about that?
>>>
>>> Regards,
>>> Jeehong Kim
>> Oh, no, this is fine by me.
>>
>>
>>
>
> Ben,
>
> If this is fine to you, could you sign off on this patch?
>
> Regards,
> Jeehong Kim.

Reviewed-By: Ben Segall 

(My understanding of signed-off-by is that I don't do that in this case)

Re: [PATCH V2] sched/fair: Fix that tasks are not constrained by cfs_b->quota on hotplug core, when hotplug core is offline and then online.

[Jeehong Kim]

On 2016년 09월 23일 01:53, bseg...@google.com wrote:
> Jeehong Kim  writes:
>
>>> Peter Zijlstra  writes:
>>>
 You forgot to Cc Ben, who gave you feedback on v1, which is rather poor
 style. Also, I don't see how kernel-janitors is relevant to this patch.
 This is very much not a janitorial thing.

 (also, why send it twice?)

 On Tue, Aug 30, 2016 at 10:12:40PM +0900, Jeehong Kim wrote:
> In case that CONFIG_HOTPLUG_CPU and CONFIG_CFS_BANDWIDTH is turned on
> and tasks in bandwidth controlled task group run on hotplug core,
> the tasks are not controlled by cfs_b->quota when hotplug core is offline
> and then online. The remaining tasks in task group consume all of
> cfs_b->quota on other cores.
>
> The cause of this problem is described as below:
>
> 1. When hotplug core is offline while tasks in task group run
> on hotplug core, unregister_fair_sched_group() deletes
> leaf_cfs_rq_list of tg->cfs_rq[cpu] from _of(cfs_rq)->leaf_cfs_rq_list.
>
> 2. Then, when hotplug core is online, update_runtime_enabled()
 Peter Zijlstra  writes:
 You forgot to Cc Ben, who gave you feedback on v1, which is rather poor
 style. Also, I don't see how kernel-janitors is relevant to this patch.
 This is very much not a janitorial thing.

 (also, why send it twice?)

 On Tue, Aug 30, 2016 at 10:12:40PM +0900, Jeehong Kim wrote:
> In case that CONFIG_HOTPLUG_CPU and CONFIG_CFS_BANDWIDTH is turned on
> and tasks in bandwidth controlled task group run on hotplug core,
> the tasks are not controlled by cfs_b->quota when hotplug core is offline
> and then online. The remaining tasks in task group consume all of
> cfs_b->quota on other cores.
>
> The cause of this problem is described as below:
>
> 1. When hotplug core is offline while tasks in task group run
> on hotplug core, unregister_fair_sched_group() deletes
> leaf_cfs_rq_list of tg->cfs_rq[cpu] from _of(cfs_rq)->leaf_cfs_rq_list.
>
> 2. Then, when hotplug core is online, update_runtime_enabled()
> registers cfs_b->quota on cfs_rq->runtime_enabled of all leaf cfs_rq
> on runqueue. However, because this is before enqueue_entity() adds
> _rq->leaf_cfs_rq_list on _of(cfs_rq)->leaf_cfs_rq_list,
> cfs->quota is not register on cfs_rq->runtime_enabled.
>
> To resolve this problem, this patch makes update_runtime_enabled()
> registers cfs_b->quota by using walk_tg_tree_from().

> +static int __maybe_unused __update_runtime_enabled(struct task_group 
> *tg, void *data)
>  {
> +struct rq *rq = data;
> +struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
> +struct cfs_bandwidth *cfs_b = _rq->tg->cfs_bandwidth;
>
> +raw_spin_lock(_b->lock);
> +raw_spin_unlock(_b->lock);
>
> +return 0;
> +}
> +
> +static void __maybe_unused update_runtime_enabled(struct rq *rq)
> +{
> +struct cfs_rq *cfs_rq = >cfs;
> +
> +/* register cfs_b->quota on the whole tg tree */
> +rcu_read_lock();
> +walk_tg_tree_from(cfs_rq->tg, __update_runtime_enabled, tg_nop, 
> (void *)rq);
> +rcu_read_unlock();
>  }
 Looks ok, performance on hotplug doesn't really matter. Ben, you happy
 with this?
>>> I'm not 100% sure about the exact timings and mechanics of hotplug, but
>>> cfs-bandwidth wise this is ok. We may still have runtime_remaining = 1,
>>> or we may have < 0 and yet be unthrottled, but either case is ok, even
>>> if hotplug allows tasks to have migrated here already (I'm not sure,
>>> looking at the code).
>>>
>>> Now that I check again you can just loop over the list of tgs rather
>>> than the hierarchical walk_tg_tree_from, but there's certainly no harm
>>> in it.
>> Ben,
>>
>> Is there additional revision which I have to do?
>> If so, could you let me know about that?
>>
>> Regards,
>> Jeehong Kim
> Oh, no, this is fine by me.
>
>
>

Ben,

If this is fine to you, could you sign off on this patch?

Regards,
Jeehong Kim.

Re: [PATCH V2] sched/fair: Fix that tasks are not constrained by cfs_b->quota on hotplug core, when hotplug core is offline and then online.

[Jeehong Kim]

On 2016년 09월 23일 01:53, bseg...@google.com wrote:
> Jeehong Kim  writes:
>
>>> Peter Zijlstra  writes:
>>>
 You forgot to Cc Ben, who gave you feedback on v1, which is rather poor
 style. Also, I don't see how kernel-janitors is relevant to this patch.
 This is very much not a janitorial thing.

 (also, why send it twice?)

 On Tue, Aug 30, 2016 at 10:12:40PM +0900, Jeehong Kim wrote:
> In case that CONFIG_HOTPLUG_CPU and CONFIG_CFS_BANDWIDTH is turned on
> and tasks in bandwidth controlled task group run on hotplug core,
> the tasks are not controlled by cfs_b->quota when hotplug core is offline
> and then online. The remaining tasks in task group consume all of
> cfs_b->quota on other cores.
>
> The cause of this problem is described as below:
>
> 1. When hotplug core is offline while tasks in task group run
> on hotplug core, unregister_fair_sched_group() deletes
> leaf_cfs_rq_list of tg->cfs_rq[cpu] from _of(cfs_rq)->leaf_cfs_rq_list.
>
> 2. Then, when hotplug core is online, update_runtime_enabled()
 Peter Zijlstra  writes:
 You forgot to Cc Ben, who gave you feedback on v1, which is rather poor
 style. Also, I don't see how kernel-janitors is relevant to this patch.
 This is very much not a janitorial thing.

 (also, why send it twice?)

 On Tue, Aug 30, 2016 at 10:12:40PM +0900, Jeehong Kim wrote:
> In case that CONFIG_HOTPLUG_CPU and CONFIG_CFS_BANDWIDTH is turned on
> and tasks in bandwidth controlled task group run on hotplug core,
> the tasks are not controlled by cfs_b->quota when hotplug core is offline
> and then online. The remaining tasks in task group consume all of
> cfs_b->quota on other cores.
>
> The cause of this problem is described as below:
>
> 1. When hotplug core is offline while tasks in task group run
> on hotplug core, unregister_fair_sched_group() deletes
> leaf_cfs_rq_list of tg->cfs_rq[cpu] from _of(cfs_rq)->leaf_cfs_rq_list.
>
> 2. Then, when hotplug core is online, update_runtime_enabled()
> registers cfs_b->quota on cfs_rq->runtime_enabled of all leaf cfs_rq
> on runqueue. However, because this is before enqueue_entity() adds
> _rq->leaf_cfs_rq_list on _of(cfs_rq)->leaf_cfs_rq_list,
> cfs->quota is not register on cfs_rq->runtime_enabled.
>
> To resolve this problem, this patch makes update_runtime_enabled()
> registers cfs_b->quota by using walk_tg_tree_from().

> +static int __maybe_unused __update_runtime_enabled(struct task_group 
> *tg, void *data)
>  {
> +struct rq *rq = data;
> +struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
> +struct cfs_bandwidth *cfs_b = _rq->tg->cfs_bandwidth;
>
> +raw_spin_lock(_b->lock);
> +raw_spin_unlock(_b->lock);
>
> +return 0;
> +}
> +
> +static void __maybe_unused update_runtime_enabled(struct rq *rq)
> +{
> +struct cfs_rq *cfs_rq = >cfs;
> +
> +/* register cfs_b->quota on the whole tg tree */
> +rcu_read_lock();
> +walk_tg_tree_from(cfs_rq->tg, __update_runtime_enabled, tg_nop, 
> (void *)rq);
> +rcu_read_unlock();
>  }
 Looks ok, performance on hotplug doesn't really matter. Ben, you happy
 with this?
>>> I'm not 100% sure about the exact timings and mechanics of hotplug, but
>>> cfs-bandwidth wise this is ok. We may still have runtime_remaining = 1,
>>> or we may have < 0 and yet be unthrottled, but either case is ok, even
>>> if hotplug allows tasks to have migrated here already (I'm not sure,
>>> looking at the code).
>>>
>>> Now that I check again you can just loop over the list of tgs rather
>>> than the hierarchical walk_tg_tree_from, but there's certainly no harm
>>> in it.
>> Ben,
>>
>> Is there additional revision which I have to do?
>> If so, could you let me know about that?
>>
>> Regards,
>> Jeehong Kim
> Oh, no, this is fine by me.
>
>
>

Ben,

If this is fine to you, could you sign off on this patch?

Regards,
Jeehong Kim.

Re: [PATCH V2] sched/fair: Fix that tasks are not constrained by cfs_b->quota on hotplug core, when hotplug core is offline and then online.

[bsegall]

Jeehong Kim  writes:

>>Peter Zijlstra  writes:
>>
>>> You forgot to Cc Ben, who gave you feedback on v1, which is rather poor
>>> style. Also, I don't see how kernel-janitors is relevant to this patch.
>>> This is very much not a janitorial thing.
>>>
>>> (also, why send it twice?)
>>>
>>> On Tue, Aug 30, 2016 at 10:12:40PM +0900, Jeehong Kim wrote:
 In case that CONFIG_HOTPLUG_CPU and CONFIG_CFS_BANDWIDTH is turned on
 and tasks in bandwidth controlled task group run on hotplug core,
 the tasks are not controlled by cfs_b->quota when hotplug core is offline
 and then online. The remaining tasks in task group consume all of
 cfs_b->quota on other cores.

 The cause of this problem is described as below:

 1. When hotplug core is offline while tasks in task group run
 on hotplug core, unregister_fair_sched_group() deletes
 leaf_cfs_rq_list of tg->cfs_rq[cpu] from _of(cfs_rq)->leaf_cfs_rq_list.

 2. Then, when hotplug core is online, update_runtime_enabled()
>>>Peter Zijlstra  writes:
>>
>>> You forgot to Cc Ben, who gave you feedback on v1, which is rather poor
>>> style. Also, I don't see how kernel-janitors is relevant to this patch.
>>> This is very much not a janitorial thing.
>>>
>>> (also, why send it twice?)
>>>
>>> On Tue, Aug 30, 2016 at 10:12:40PM +0900, Jeehong Kim wrote:
 In case that CONFIG_HOTPLUG_CPU and CONFIG_CFS_BANDWIDTH is turned on
 and tasks in bandwidth controlled task group run on hotplug core,
 the tasks are not controlled by cfs_b->quota when hotplug core is offline
 and then online. The remaining tasks in task group consume all of
 cfs_b->quota on other cores.

 The cause of this problem is described as below:

 1. When hotplug core is offline while tasks in task group run
 on hotplug core, unregister_fair_sched_group() deletes
 leaf_cfs_rq_list of tg->cfs_rq[cpu] from _of(cfs_rq)->leaf_cfs_rq_list.

 2. Then, when hotplug core is online, update_runtime_enabled()
 registers cfs_b->quota on cfs_rq->runtime_enabled of all leaf cfs_rq
 on runqueue. However, because this is before enqueue_entity() adds
 _rq->leaf_cfs_rq_list on _of(cfs_rq)->leaf_cfs_rq_list,
 cfs->quota is not register on cfs_rq->runtime_enabled.

 To resolve this problem, this patch makes update_runtime_enabled()
 registers cfs_b->quota by using walk_tg_tree_from().
>>>
>>>
 +static int __maybe_unused __update_runtime_enabled(struct task_group *tg, 
 void *data)
  {
 +struct rq *rq = data;
 +struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
 +struct cfs_bandwidth *cfs_b = _rq->tg->cfs_bandwidth;

 +raw_spin_lock(_b->lock);
 +raw_spin_unlock(_b->lock);

 +return 0;
 +}
 +
 +static void __maybe_unused update_runtime_enabled(struct rq *rq)
 +{
 +struct cfs_rq *cfs_rq = >cfs;
 +
 +/* register cfs_b->quota on the whole tg tree */
 +rcu_read_lock();
 +walk_tg_tree_from(cfs_rq->tg, __update_runtime_enabled, tg_nop, (void 
 *)rq);
 +rcu_read_unlock();
  }
>>>
>>> Looks ok, performance on hotplug doesn't really matter. Ben, you happy
>>> with this?
>>
>> I'm not 100% sure about the exact timings and mechanics of hotplug, but
>> cfs-bandwidth wise this is ok. We may still have runtime_remaining = 1,
>> or we may have < 0 and yet be unthrottled, but either case is ok, even
>> if hotplug allows tasks to have migrated here already (I'm not sure,
>> looking at the code).
>>
>> Now that I check again you can just loop over the list of tgs rather
>> than the hierarchical walk_tg_tree_from, but there's certainly no harm
>> in it.
>
> Ben,
>
> Is there additional revision which I have to do?
> If so, could you let me know about that?
>
> Regards,
> Jeehong Kim

Oh, no, this is fine by me.

Re: [PATCH V2] sched/fair: Fix that tasks are not constrained by cfs_b->quota on hotplug core, when hotplug core is offline and then online.

[bsegall]

Jeehong Kim  writes:

>>Peter Zijlstra  writes:
>>
>>> You forgot to Cc Ben, who gave you feedback on v1, which is rather poor
>>> style. Also, I don't see how kernel-janitors is relevant to this patch.
>>> This is very much not a janitorial thing.
>>>
>>> (also, why send it twice?)
>>>
>>> On Tue, Aug 30, 2016 at 10:12:40PM +0900, Jeehong Kim wrote:
 In case that CONFIG_HOTPLUG_CPU and CONFIG_CFS_BANDWIDTH is turned on
 and tasks in bandwidth controlled task group run on hotplug core,
 the tasks are not controlled by cfs_b->quota when hotplug core is offline
 and then online. The remaining tasks in task group consume all of
 cfs_b->quota on other cores.

 The cause of this problem is described as below:

 1. When hotplug core is offline while tasks in task group run
 on hotplug core, unregister_fair_sched_group() deletes
 leaf_cfs_rq_list of tg->cfs_rq[cpu] from _of(cfs_rq)->leaf_cfs_rq_list.

 2. Then, when hotplug core is online, update_runtime_enabled()
>>>Peter Zijlstra  writes:
>>
>>> You forgot to Cc Ben, who gave you feedback on v1, which is rather poor
>>> style. Also, I don't see how kernel-janitors is relevant to this patch.
>>> This is very much not a janitorial thing.
>>>
>>> (also, why send it twice?)
>>>
>>> On Tue, Aug 30, 2016 at 10:12:40PM +0900, Jeehong Kim wrote:
 In case that CONFIG_HOTPLUG_CPU and CONFIG_CFS_BANDWIDTH is turned on
 and tasks in bandwidth controlled task group run on hotplug core,
 the tasks are not controlled by cfs_b->quota when hotplug core is offline
 and then online. The remaining tasks in task group consume all of
 cfs_b->quota on other cores.

 The cause of this problem is described as below:

 1. When hotplug core is offline while tasks in task group run
 on hotplug core, unregister_fair_sched_group() deletes
 leaf_cfs_rq_list of tg->cfs_rq[cpu] from _of(cfs_rq)->leaf_cfs_rq_list.

 2. Then, when hotplug core is online, update_runtime_enabled()
 registers cfs_b->quota on cfs_rq->runtime_enabled of all leaf cfs_rq
 on runqueue. However, because this is before enqueue_entity() adds
 _rq->leaf_cfs_rq_list on _of(cfs_rq)->leaf_cfs_rq_list,
 cfs->quota is not register on cfs_rq->runtime_enabled.

 To resolve this problem, this patch makes update_runtime_enabled()
 registers cfs_b->quota by using walk_tg_tree_from().
>>>
>>>
 +static int __maybe_unused __update_runtime_enabled(struct task_group *tg, 
 void *data)
  {
 +struct rq *rq = data;
 +struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
 +struct cfs_bandwidth *cfs_b = _rq->tg->cfs_bandwidth;

 +raw_spin_lock(_b->lock);
 +raw_spin_unlock(_b->lock);

 +return 0;
 +}
 +
 +static void __maybe_unused update_runtime_enabled(struct rq *rq)
 +{
 +struct cfs_rq *cfs_rq = >cfs;
 +
 +/* register cfs_b->quota on the whole tg tree */
 +rcu_read_lock();
 +walk_tg_tree_from(cfs_rq->tg, __update_runtime_enabled, tg_nop, (void 
 *)rq);
 +rcu_read_unlock();
  }
>>>
>>> Looks ok, performance on hotplug doesn't really matter. Ben, you happy
>>> with this?
>>
>> I'm not 100% sure about the exact timings and mechanics of hotplug, but
>> cfs-bandwidth wise this is ok. We may still have runtime_remaining = 1,
>> or we may have < 0 and yet be unthrottled, but either case is ok, even
>> if hotplug allows tasks to have migrated here already (I'm not sure,
>> looking at the code).
>>
>> Now that I check again you can just loop over the list of tgs rather
>> than the hierarchical walk_tg_tree_from, but there's certainly no harm
>> in it.
>
> Ben,
>
> Is there additional revision which I have to do?
> If so, could you let me know about that?
>
> Regards,
> Jeehong Kim

Oh, no, this is fine by me.

Re: [PATCH V2] sched/fair: Fix that tasks are not constrained by cfs_b->quota on hotplug core, when hotplug core is offline and then online.

[Jeehong Kim]

>Peter Zijlstra  writes:
>
>> You forgot to Cc Ben, who gave you feedback on v1, which is rather poor
>> style. Also, I don't see how kernel-janitors is relevant to this patch.
>> This is very much not a janitorial thing.
>>
>> (also, why send it twice?)
>>
>> On Tue, Aug 30, 2016 at 10:12:40PM +0900, Jeehong Kim wrote:
>>> In case that CONFIG_HOTPLUG_CPU and CONFIG_CFS_BANDWIDTH is turned on
>>> and tasks in bandwidth controlled task group run on hotplug core,
>>> the tasks are not controlled by cfs_b->quota when hotplug core is offline
>>> and then online. The remaining tasks in task group consume all of
>>> cfs_b->quota on other cores.
>>>
>>> The cause of this problem is described as below:
>>>
>>> 1. When hotplug core is offline while tasks in task group run
>>> on hotplug core, unregister_fair_sched_group() deletes
>>> leaf_cfs_rq_list of tg->cfs_rq[cpu] from _of(cfs_rq)->leaf_cfs_rq_list.
>>>
>>> 2. Then, when hotplug core is online, update_runtime_enabled()
>>Peter Zijlstra  writes:
>
>> You forgot to Cc Ben, who gave you feedback on v1, which is rather poor
>> style. Also, I don't see how kernel-janitors is relevant to this patch.
>> This is very much not a janitorial thing.
>>
>> (also, why send it twice?)
>>
>> On Tue, Aug 30, 2016 at 10:12:40PM +0900, Jeehong Kim wrote:
>>> In case that CONFIG_HOTPLUG_CPU and CONFIG_CFS_BANDWIDTH is turned on
>>> and tasks in bandwidth controlled task group run on hotplug core,
>>> the tasks are not controlled by cfs_b->quota when hotplug core is offline
>>> and then online. The remaining tasks in task group consume all of
>>> cfs_b->quota on other cores.
>>>
>>> The cause of this problem is described as below:
>>>
>>> 1. When hotplug core is offline while tasks in task group run
>>> on hotplug core, unregister_fair_sched_group() deletes
>>> leaf_cfs_rq_list of tg->cfs_rq[cpu] from _of(cfs_rq)->leaf_cfs_rq_list.
>>>
>>> 2. Then, when hotplug core is online, update_runtime_enabled()
>>> registers cfs_b->quota on cfs_rq->runtime_enabled of all leaf cfs_rq
>>> on runqueue. However, because this is before enqueue_entity() adds
>>> _rq->leaf_cfs_rq_list on _of(cfs_rq)->leaf_cfs_rq_list,
>>> cfs->quota is not register on cfs_rq->runtime_enabled.
>>>
>>> To resolve this problem, this patch makes update_runtime_enabled()
>>> registers cfs_b->quota by using walk_tg_tree_from().
>>
>>
>>> +static int __maybe_unused __update_runtime_enabled(struct task_group *tg, 
>>> void *data)
>>>  {
>>> +struct rq *rq = data;
>>> +struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
>>> +struct cfs_bandwidth *cfs_b = _rq->tg->cfs_bandwidth;
>>>
>>> +raw_spin_lock(_b->lock);
>>> +raw_spin_unlock(_b->lock);
>>>
>>> +return 0;
>>> +}
>>> +
>>> +static void __maybe_unused update_runtime_enabled(struct rq *rq)
>>> +{
>>> +struct cfs_rq *cfs_rq = >cfs;
>>> +
>>> +/* register cfs_b->quota on the whole tg tree */
>>> +rcu_read_lock();
>>> +walk_tg_tree_from(cfs_rq->tg, __update_runtime_enabled, tg_nop, (void 
>>> *)rq);
>>> +rcu_read_unlock();
>>>  }
>>
>> Looks ok, performance on hotplug doesn't really matter. Ben, you happy
>> with this?
>
> I'm not 100% sure about the exact timings and mechanics of hotplug, but
> cfs-bandwidth wise this is ok. We may still have runtime_remaining = 1,
> or we may have < 0 and yet be unthrottled, but either case is ok, even
> if hotplug allows tasks to have migrated here already (I'm not sure,
> looking at the code).
>
> Now that I check again you can just loop over the list of tgs rather
> than the hierarchical walk_tg_tree_from, but there's certainly no harm
> in it.

Ben,

Is there additional revision which I have to do?
If so, could you let me know about that?

Regards,
Jeehong Kim

Re: [PATCH V2] sched/fair: Fix that tasks are not constrained by cfs_b->quota on hotplug core, when hotplug core is offline and then online.

[Jeehong Kim]

>Peter Zijlstra  writes:
>
>> You forgot to Cc Ben, who gave you feedback on v1, which is rather poor
>> style. Also, I don't see how kernel-janitors is relevant to this patch.
>> This is very much not a janitorial thing.
>>
>> (also, why send it twice?)
>>
>> On Tue, Aug 30, 2016 at 10:12:40PM +0900, Jeehong Kim wrote:
>>> In case that CONFIG_HOTPLUG_CPU and CONFIG_CFS_BANDWIDTH is turned on
>>> and tasks in bandwidth controlled task group run on hotplug core,
>>> the tasks are not controlled by cfs_b->quota when hotplug core is offline
>>> and then online. The remaining tasks in task group consume all of
>>> cfs_b->quota on other cores.
>>>
>>> The cause of this problem is described as below:
>>>
>>> 1. When hotplug core is offline while tasks in task group run
>>> on hotplug core, unregister_fair_sched_group() deletes
>>> leaf_cfs_rq_list of tg->cfs_rq[cpu] from _of(cfs_rq)->leaf_cfs_rq_list.
>>>
>>> 2. Then, when hotplug core is online, update_runtime_enabled()
>>Peter Zijlstra  writes:
>
>> You forgot to Cc Ben, who gave you feedback on v1, which is rather poor
>> style. Also, I don't see how kernel-janitors is relevant to this patch.
>> This is very much not a janitorial thing.
>>
>> (also, why send it twice?)
>>
>> On Tue, Aug 30, 2016 at 10:12:40PM +0900, Jeehong Kim wrote:
>>> In case that CONFIG_HOTPLUG_CPU and CONFIG_CFS_BANDWIDTH is turned on
>>> and tasks in bandwidth controlled task group run on hotplug core,
>>> the tasks are not controlled by cfs_b->quota when hotplug core is offline
>>> and then online. The remaining tasks in task group consume all of
>>> cfs_b->quota on other cores.
>>>
>>> The cause of this problem is described as below:
>>>
>>> 1. When hotplug core is offline while tasks in task group run
>>> on hotplug core, unregister_fair_sched_group() deletes
>>> leaf_cfs_rq_list of tg->cfs_rq[cpu] from _of(cfs_rq)->leaf_cfs_rq_list.
>>>
>>> 2. Then, when hotplug core is online, update_runtime_enabled()
>>> registers cfs_b->quota on cfs_rq->runtime_enabled of all leaf cfs_rq
>>> on runqueue. However, because this is before enqueue_entity() adds
>>> _rq->leaf_cfs_rq_list on _of(cfs_rq)->leaf_cfs_rq_list,
>>> cfs->quota is not register on cfs_rq->runtime_enabled.
>>>
>>> To resolve this problem, this patch makes update_runtime_enabled()
>>> registers cfs_b->quota by using walk_tg_tree_from().
>>
>>
>>> +static int __maybe_unused __update_runtime_enabled(struct task_group *tg, 
>>> void *data)
>>>  {
>>> +struct rq *rq = data;
>>> +struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
>>> +struct cfs_bandwidth *cfs_b = _rq->tg->cfs_bandwidth;
>>>
>>> +raw_spin_lock(_b->lock);
>>> +raw_spin_unlock(_b->lock);
>>>
>>> +return 0;
>>> +}
>>> +
>>> +static void __maybe_unused update_runtime_enabled(struct rq *rq)
>>> +{
>>> +struct cfs_rq *cfs_rq = >cfs;
>>> +
>>> +/* register cfs_b->quota on the whole tg tree */
>>> +rcu_read_lock();
>>> +walk_tg_tree_from(cfs_rq->tg, __update_runtime_enabled, tg_nop, (void 
>>> *)rq);
>>> +rcu_read_unlock();
>>>  }
>>
>> Looks ok, performance on hotplug doesn't really matter. Ben, you happy
>> with this?
>
> I'm not 100% sure about the exact timings and mechanics of hotplug, but
> cfs-bandwidth wise this is ok. We may still have runtime_remaining = 1,
> or we may have < 0 and yet be unthrottled, but either case is ok, even
> if hotplug allows tasks to have migrated here already (I'm not sure,
> looking at the code).
>
> Now that I check again you can just loop over the list of tgs rather
> than the hierarchical walk_tg_tree_from, but there's certainly no harm
> in it.

Ben,

Is there additional revision which I have to do?
If so, could you let me know about that?

Regards,
Jeehong Kim

Re: [PATCH V2] sched/fair: Fix that tasks are not constrained by cfs_b->quota on hotplug core, when hotplug core is offline and then online.

[bsegall]

Peter Zijlstra  writes:

> You forgot to Cc Ben, who gave you feedback on v1, which is rather poor
> style. Also, I don't see how kernel-janitors is relevant to this patch.
> This is very much not a janitorial thing.
>
> (also, why send it twice?)
>
> On Tue, Aug 30, 2016 at 10:12:40PM +0900, Jeehong Kim wrote:
>> In case that CONFIG_HOTPLUG_CPU and CONFIG_CFS_BANDWIDTH is turned on
>> and tasks in bandwidth controlled task group run on hotplug core,
>> the tasks are not controlled by cfs_b->quota when hotplug core is offline
>> and then online. The remaining tasks in task group consume all of
>> cfs_b->quota on other cores.
>> 
>> The cause of this problem is described as below:
>> 
>> 1. When hotplug core is offline while tasks in task group run
>> on hotplug core, unregister_fair_sched_group() deletes
>> leaf_cfs_rq_list of tg->cfs_rq[cpu] from _of(cfs_rq)->leaf_cfs_rq_list.
>> 
>> 2. Then, when hotplug core is online, update_runtime_enabled()
>> registers cfs_b->quota on cfs_rq->runtime_enabled of all leaf cfs_rq
>> on runqueue. However, because this is before enqueue_entity() adds
>> _rq->leaf_cfs_rq_list on _of(cfs_rq)->leaf_cfs_rq_list,
>> cfs->quota is not register on cfs_rq->runtime_enabled.
>> 
>> To resolve this problem, this patch makes update_runtime_enabled()
>> registers cfs_b->quota by using walk_tg_tree_from().
>
>
>> +static int __maybe_unused __update_runtime_enabled(struct task_group *tg, 
>> void *data)
>>  {
>> +struct rq *rq = data;
>> +struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
>> +struct cfs_bandwidth *cfs_b = _rq->tg->cfs_bandwidth;
>> 
>> +raw_spin_lock(_b->lock);
>> +cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF;
>> +raw_spin_unlock(_b->lock);
>> 
>> +return 0;
>> +}
>> +
>> +static void __maybe_unused update_runtime_enabled(struct rq *rq)
>> +{
>> +struct cfs_rq *cfs_rq = >cfs;
>> +
>> +/* register cfs_b->quota on the whole tg tree */
>> +rcu_read_lock();
>> +walk_tg_tree_from(cfs_rq->tg, __update_runtime_enabled, tg_nop, (void 
>> *)rq);
>> +rcu_read_unlock();
>>  }
>
> Looks ok, performance on hotplug doesn't really matter. Ben, you happy
> with this?

I'm not 100% sure about the exact timings and mechanics of hotplug, but
cfs-bandwidth wise this is ok. We may still have runtime_remaining = 1,
or we may have < 0 and yet be unthrottled, but either case is ok, even
if hotplug allows tasks to have migrated here already (I'm not sure,
looking at the code).

Now that I check again you can just loop over the list of tgs rather
than the hierarchical walk_tg_tree_from, but there's certainly no harm
in it.

Re: [PATCH V2] sched/fair: Fix that tasks are not constrained by cfs_b->quota on hotplug core, when hotplug core is offline and then online.

[bsegall]

Peter Zijlstra  writes:

> You forgot to Cc Ben, who gave you feedback on v1, which is rather poor
> style. Also, I don't see how kernel-janitors is relevant to this patch.
> This is very much not a janitorial thing.
>
> (also, why send it twice?)
>
> On Tue, Aug 30, 2016 at 10:12:40PM +0900, Jeehong Kim wrote:
>> In case that CONFIG_HOTPLUG_CPU and CONFIG_CFS_BANDWIDTH is turned on
>> and tasks in bandwidth controlled task group run on hotplug core,
>> the tasks are not controlled by cfs_b->quota when hotplug core is offline
>> and then online. The remaining tasks in task group consume all of
>> cfs_b->quota on other cores.
>> 
>> The cause of this problem is described as below:
>> 
>> 1. When hotplug core is offline while tasks in task group run
>> on hotplug core, unregister_fair_sched_group() deletes
>> leaf_cfs_rq_list of tg->cfs_rq[cpu] from _of(cfs_rq)->leaf_cfs_rq_list.
>> 
>> 2. Then, when hotplug core is online, update_runtime_enabled()
>> registers cfs_b->quota on cfs_rq->runtime_enabled of all leaf cfs_rq
>> on runqueue. However, because this is before enqueue_entity() adds
>> _rq->leaf_cfs_rq_list on _of(cfs_rq)->leaf_cfs_rq_list,
>> cfs->quota is not register on cfs_rq->runtime_enabled.
>> 
>> To resolve this problem, this patch makes update_runtime_enabled()
>> registers cfs_b->quota by using walk_tg_tree_from().
>
>
>> +static int __maybe_unused __update_runtime_enabled(struct task_group *tg, 
>> void *data)
>>  {
>> +struct rq *rq = data;
>> +struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
>> +struct cfs_bandwidth *cfs_b = _rq->tg->cfs_bandwidth;
>> 
>> +raw_spin_lock(_b->lock);
>> +cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF;
>> +raw_spin_unlock(_b->lock);
>> 
>> +return 0;
>> +}
>> +
>> +static void __maybe_unused update_runtime_enabled(struct rq *rq)
>> +{
>> +struct cfs_rq *cfs_rq = >cfs;
>> +
>> +/* register cfs_b->quota on the whole tg tree */
>> +rcu_read_lock();
>> +walk_tg_tree_from(cfs_rq->tg, __update_runtime_enabled, tg_nop, (void 
>> *)rq);
>> +rcu_read_unlock();
>>  }
>
> Looks ok, performance on hotplug doesn't really matter. Ben, you happy
> with this?

I'm not 100% sure about the exact timings and mechanics of hotplug, but
cfs-bandwidth wise this is ok. We may still have runtime_remaining = 1,
or we may have < 0 and yet be unthrottled, but either case is ok, even
if hotplug allows tasks to have migrated here already (I'm not sure,
looking at the code).

Now that I check again you can just loop over the list of tgs rather
than the hierarchical walk_tg_tree_from, but there's certainly no harm
in it.

Re: [PATCH V2] sched/fair: Fix that tasks are not constrained by cfs_b->quota on hotplug core, when hotplug core is offline and then online.

[Jeehong Kim]

Hello,

First of all, thanks for review. And I am sorry that I forgot to CC Ben.

The reason why I sent last mail twice is that I forgot including the comments 
for changes from PATCH V1.

Thanks and BR.

On 2016년 09월 01일 20:01, Peter Zijlstra wrote:
> You forgot to Cc Ben, who gave you feedback on v1, which is rather poor
> style. Also, I don't see how kernel-janitors is relevant to this patch.
> This is very much not a janitorial thing.
>
> (also, why send it twice?)
>
> On Tue, Aug 30, 2016 at 10:12:40PM +0900, Jeehong Kim wrote:
>> In case that CONFIG_HOTPLUG_CPU and CONFIG_CFS_BANDWIDTH is turned on
>> and tasks in bandwidth controlled task group run on hotplug core,
>> the tasks are not controlled by cfs_b->quota when hotplug core is offline
>> and then online. The remaining tasks in task group consume all of
>> cfs_b->quota on other cores.
>>
>> The cause of this problem is described as below:
>>
>> 1. When hotplug core is offline while tasks in task group run
>> on hotplug core, unregister_fair_sched_group() deletes
>> leaf_cfs_rq_list of tg->cfs_rq[cpu] from _of(cfs_rq)->leaf_cfs_rq_list.
>>
>> 2. Then, when hotplug core is online, update_runtime_enabled()
>> registers cfs_b->quota on cfs_rq->runtime_enabled of all leaf cfs_rq
>> on runqueue. However, because this is before enqueue_entity() adds
>> _rq->leaf_cfs_rq_list on _of(cfs_rq)->leaf_cfs_rq_list,
>> cfs->quota is not register on cfs_rq->runtime_enabled.
>>
>> To resolve this problem, this patch makes update_runtime_enabled()
>> registers cfs_b->quota by using walk_tg_tree_from().
>
>> +static int __maybe_unused __update_runtime_enabled(struct task_group *tg, 
>> void *data)
>>  {
>> +struct rq *rq = data;
>> +struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
>> +struct cfs_bandwidth *cfs_b = _rq->tg->cfs_bandwidth;
>>
>> +raw_spin_lock(_b->lock);
>> +cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF;
>> +raw_spin_unlock(_b->lock);
>>
>> +return 0;
>> +}
>> +
>> +static void __maybe_unused update_runtime_enabled(struct rq *rq)
>> +{
>> +struct cfs_rq *cfs_rq = >cfs;
>> +
>> +/* register cfs_b->quota on the whole tg tree */
>> +rcu_read_lock();
>> +walk_tg_tree_from(cfs_rq->tg, __update_runtime_enabled, tg_nop, (void 
>> *)rq);
>> +rcu_read_unlock();
>>  }
> Looks ok, performance on hotplug doesn't really matter. Ben, you happy
> with this?
>
>
>

Re: [PATCH V2] sched/fair: Fix that tasks are not constrained by cfs_b->quota on hotplug core, when hotplug core is offline and then online.

[Jeehong Kim]

Hello,

First of all, thanks for review. And I am sorry that I forgot to CC Ben.

The reason why I sent last mail twice is that I forgot including the comments 
for changes from PATCH V1.

Thanks and BR.

On 2016년 09월 01일 20:01, Peter Zijlstra wrote:
> You forgot to Cc Ben, who gave you feedback on v1, which is rather poor
> style. Also, I don't see how kernel-janitors is relevant to this patch.
> This is very much not a janitorial thing.
>
> (also, why send it twice?)
>
> On Tue, Aug 30, 2016 at 10:12:40PM +0900, Jeehong Kim wrote:
>> In case that CONFIG_HOTPLUG_CPU and CONFIG_CFS_BANDWIDTH is turned on
>> and tasks in bandwidth controlled task group run on hotplug core,
>> the tasks are not controlled by cfs_b->quota when hotplug core is offline
>> and then online. The remaining tasks in task group consume all of
>> cfs_b->quota on other cores.
>>
>> The cause of this problem is described as below:
>>
>> 1. When hotplug core is offline while tasks in task group run
>> on hotplug core, unregister_fair_sched_group() deletes
>> leaf_cfs_rq_list of tg->cfs_rq[cpu] from _of(cfs_rq)->leaf_cfs_rq_list.
>>
>> 2. Then, when hotplug core is online, update_runtime_enabled()
>> registers cfs_b->quota on cfs_rq->runtime_enabled of all leaf cfs_rq
>> on runqueue. However, because this is before enqueue_entity() adds
>> _rq->leaf_cfs_rq_list on _of(cfs_rq)->leaf_cfs_rq_list,
>> cfs->quota is not register on cfs_rq->runtime_enabled.
>>
>> To resolve this problem, this patch makes update_runtime_enabled()
>> registers cfs_b->quota by using walk_tg_tree_from().
>
>> +static int __maybe_unused __update_runtime_enabled(struct task_group *tg, 
>> void *data)
>>  {
>> +struct rq *rq = data;
>> +struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
>> +struct cfs_bandwidth *cfs_b = _rq->tg->cfs_bandwidth;
>>
>> +raw_spin_lock(_b->lock);
>> +cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF;
>> +raw_spin_unlock(_b->lock);
>>
>> +return 0;
>> +}
>> +
>> +static void __maybe_unused update_runtime_enabled(struct rq *rq)
>> +{
>> +struct cfs_rq *cfs_rq = >cfs;
>> +
>> +/* register cfs_b->quota on the whole tg tree */
>> +rcu_read_lock();
>> +walk_tg_tree_from(cfs_rq->tg, __update_runtime_enabled, tg_nop, (void 
>> *)rq);
>> +rcu_read_unlock();
>>  }
> Looks ok, performance on hotplug doesn't really matter. Ben, you happy
> with this?
>
>
>

Re: [PATCH V2] sched/fair: Fix that tasks are not constrained by cfs_b->quota on hotplug core, when hotplug core is offline and then online.

[Peter Zijlstra]

You forgot to Cc Ben, who gave you feedback on v1, which is rather poor
style. Also, I don't see how kernel-janitors is relevant to this patch.
This is very much not a janitorial thing.

(also, why send it twice?)

On Tue, Aug 30, 2016 at 10:12:40PM +0900, Jeehong Kim wrote:
> In case that CONFIG_HOTPLUG_CPU and CONFIG_CFS_BANDWIDTH is turned on
> and tasks in bandwidth controlled task group run on hotplug core,
> the tasks are not controlled by cfs_b->quota when hotplug core is offline
> and then online. The remaining tasks in task group consume all of
> cfs_b->quota on other cores.
> 
> The cause of this problem is described as below:
> 
> 1. When hotplug core is offline while tasks in task group run
> on hotplug core, unregister_fair_sched_group() deletes
> leaf_cfs_rq_list of tg->cfs_rq[cpu] from _of(cfs_rq)->leaf_cfs_rq_list.
> 
> 2. Then, when hotplug core is online, update_runtime_enabled()
> registers cfs_b->quota on cfs_rq->runtime_enabled of all leaf cfs_rq
> on runqueue. However, because this is before enqueue_entity() adds
> _rq->leaf_cfs_rq_list on _of(cfs_rq)->leaf_cfs_rq_list,
> cfs->quota is not register on cfs_rq->runtime_enabled.
> 
> To resolve this problem, this patch makes update_runtime_enabled()
> registers cfs_b->quota by using walk_tg_tree_from().


> +static int __maybe_unused __update_runtime_enabled(struct task_group *tg, 
> void *data)
>  {
> + struct rq *rq = data;
> + struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
> + struct cfs_bandwidth *cfs_b = _rq->tg->cfs_bandwidth;
> 
> + raw_spin_lock(_b->lock);
> + cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF;
> + raw_spin_unlock(_b->lock);
> 
> + return 0;
> +}
> +
> +static void __maybe_unused update_runtime_enabled(struct rq *rq)
> +{
> + struct cfs_rq *cfs_rq = >cfs;
> +
> + /* register cfs_b->quota on the whole tg tree */
> + rcu_read_lock();
> + walk_tg_tree_from(cfs_rq->tg, __update_runtime_enabled, tg_nop, (void 
> *)rq);
> + rcu_read_unlock();
>  }

Looks ok, performance on hotplug doesn't really matter. Ben, you happy
with this?

Re: [PATCH V2] sched/fair: Fix that tasks are not constrained by cfs_b->quota on hotplug core, when hotplug core is offline and then online.

[Peter Zijlstra]

You forgot to Cc Ben, who gave you feedback on v1, which is rather poor
style. Also, I don't see how kernel-janitors is relevant to this patch.
This is very much not a janitorial thing.

(also, why send it twice?)

On Tue, Aug 30, 2016 at 10:12:40PM +0900, Jeehong Kim wrote:
> In case that CONFIG_HOTPLUG_CPU and CONFIG_CFS_BANDWIDTH is turned on
> and tasks in bandwidth controlled task group run on hotplug core,
> the tasks are not controlled by cfs_b->quota when hotplug core is offline
> and then online. The remaining tasks in task group consume all of
> cfs_b->quota on other cores.
> 
> The cause of this problem is described as below:
> 
> 1. When hotplug core is offline while tasks in task group run
> on hotplug core, unregister_fair_sched_group() deletes
> leaf_cfs_rq_list of tg->cfs_rq[cpu] from _of(cfs_rq)->leaf_cfs_rq_list.
> 
> 2. Then, when hotplug core is online, update_runtime_enabled()
> registers cfs_b->quota on cfs_rq->runtime_enabled of all leaf cfs_rq
> on runqueue. However, because this is before enqueue_entity() adds
> _rq->leaf_cfs_rq_list on _of(cfs_rq)->leaf_cfs_rq_list,
> cfs->quota is not register on cfs_rq->runtime_enabled.
> 
> To resolve this problem, this patch makes update_runtime_enabled()
> registers cfs_b->quota by using walk_tg_tree_from().


> +static int __maybe_unused __update_runtime_enabled(struct task_group *tg, 
> void *data)
>  {
> + struct rq *rq = data;
> + struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
> + struct cfs_bandwidth *cfs_b = _rq->tg->cfs_bandwidth;
> 
> + raw_spin_lock(_b->lock);
> + cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF;
> + raw_spin_unlock(_b->lock);
> 
> + return 0;
> +}
> +
> +static void __maybe_unused update_runtime_enabled(struct rq *rq)
> +{
> + struct cfs_rq *cfs_rq = >cfs;
> +
> + /* register cfs_b->quota on the whole tg tree */
> + rcu_read_lock();
> + walk_tg_tree_from(cfs_rq->tg, __update_runtime_enabled, tg_nop, (void 
> *)rq);
> + rcu_read_unlock();
>  }

Looks ok, performance on hotplug doesn't really matter. Ben, you happy
with this?

[PATCH V2] sched/fair: Fix that tasks are not constrained by cfs_b->quota on hotplug core, when hotplug core is offline and then online.

[Jeehong Kim]

In case that CONFIG_HOTPLUG_CPU and CONFIG_CFS_BANDWIDTH is turned on
and tasks in bandwidth controlled task group run on hotplug core,
the tasks are not controlled by cfs_b->quota when hotplug core is offline
and then online. The remaining tasks in task group consume all of
cfs_b->quota on other cores.

The cause of this problem is described as below:

1. When hotplug core is offline while tasks in task group run
on hotplug core, unregister_fair_sched_group() deletes
leaf_cfs_rq_list of tg->cfs_rq[cpu] from _of(cfs_rq)->leaf_cfs_rq_list.

2. Then, when hotplug core is online, update_runtime_enabled()
registers cfs_b->quota on cfs_rq->runtime_enabled of all leaf cfs_rq
on runqueue. However, because this is before enqueue_entity() adds
_rq->leaf_cfs_rq_list on _of(cfs_rq)->leaf_cfs_rq_list,
cfs->quota is not register on cfs_rq->runtime_enabled.

To resolve this problem, this patch makes update_runtime_enabled()
registers cfs_b->quota by using walk_tg_tree_from().

Signed-off-by: Jeehong Kim 
---
V2: update_runtime_enabled() walks the whole tg tree,
instead of register quota on every enqueue.

kernel/sched/fair.c | 32 +---
 1 file changed, 21 insertions(+), 11 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 6488815..63b376d 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4373,17 +4373,27 @@ static void destroy_cfs_bandwidth(struct cfs_bandwidth 
*cfs_b)
hrtimer_cancel(_b->slack_timer);
 }

-static void __maybe_unused update_runtime_enabled(struct rq *rq)
+static int __maybe_unused __update_runtime_enabled(struct task_group *tg, void 
*data)
 {
-   struct cfs_rq *cfs_rq;
+   struct rq *rq = data;
+   struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
+   struct cfs_bandwidth *cfs_b = _rq->tg->cfs_bandwidth;

-   for_each_leaf_cfs_rq(rq, cfs_rq) {
-   struct cfs_bandwidth *cfs_b = _rq->tg->cfs_bandwidth;
+   raw_spin_lock(_b->lock);
+   cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF;
+   raw_spin_unlock(_b->lock);

-   raw_spin_lock(_b->lock);
-   cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF;
-   raw_spin_unlock(_b->lock);
-   }
+   return 0;
+}
+
+static void __maybe_unused update_runtime_enabled(struct rq *rq)
+{
+   struct cfs_rq *cfs_rq = >cfs;
+
+   /* register cfs_b->quota on the whole tg tree */
+   rcu_read_lock();
+   walk_tg_tree_from(cfs_rq->tg, __update_runtime_enabled, tg_nop, (void 
*)rq);
+   rcu_read_unlock();
 }
--

[PATCH V2] sched/fair: Fix that tasks are not constrained by cfs_b->quota on hotplug core, when hotplug core is offline and then online.

[Jeehong Kim]

In case that CONFIG_HOTPLUG_CPU and CONFIG_CFS_BANDWIDTH is turned on
and tasks in bandwidth controlled task group run on hotplug core,
the tasks are not controlled by cfs_b->quota when hotplug core is offline
and then online. The remaining tasks in task group consume all of
cfs_b->quota on other cores.

The cause of this problem is described as below:

1. When hotplug core is offline while tasks in task group run
on hotplug core, unregister_fair_sched_group() deletes
leaf_cfs_rq_list of tg->cfs_rq[cpu] from _of(cfs_rq)->leaf_cfs_rq_list.

2. Then, when hotplug core is online, update_runtime_enabled()
registers cfs_b->quota on cfs_rq->runtime_enabled of all leaf cfs_rq
on runqueue. However, because this is before enqueue_entity() adds
_rq->leaf_cfs_rq_list on _of(cfs_rq)->leaf_cfs_rq_list,
cfs->quota is not register on cfs_rq->runtime_enabled.

To resolve this problem, this patch makes update_runtime_enabled()
registers cfs_b->quota by using walk_tg_tree_from().

Signed-off-by: Jeehong Kim 
---
V2: update_runtime_enabled() walks the whole tg tree,
instead of register quota on every enqueue.

kernel/sched/fair.c | 32 +---
 1 file changed, 21 insertions(+), 11 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 6488815..63b376d 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4373,17 +4373,27 @@ static void destroy_cfs_bandwidth(struct cfs_bandwidth 
*cfs_b)
hrtimer_cancel(_b->slack_timer);
 }

-static void __maybe_unused update_runtime_enabled(struct rq *rq)
+static int __maybe_unused __update_runtime_enabled(struct task_group *tg, void 
*data)
 {
-   struct cfs_rq *cfs_rq;
+   struct rq *rq = data;
+   struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
+   struct cfs_bandwidth *cfs_b = _rq->tg->cfs_bandwidth;

-   for_each_leaf_cfs_rq(rq, cfs_rq) {
-   struct cfs_bandwidth *cfs_b = _rq->tg->cfs_bandwidth;
+   raw_spin_lock(_b->lock);
+   cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF;
+   raw_spin_unlock(_b->lock);

-   raw_spin_lock(_b->lock);
-   cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF;
-   raw_spin_unlock(_b->lock);
-   }
+   return 0;
+}
+
+static void __maybe_unused update_runtime_enabled(struct rq *rq)
+{
+   struct cfs_rq *cfs_rq = >cfs;
+
+   /* register cfs_b->quota on the whole tg tree */
+   rcu_read_lock();
+   walk_tg_tree_from(cfs_rq->tg, __update_runtime_enabled, tg_nop, (void 
*)rq);
+   rcu_read_unlock();
 }
--

[PATCH V2] sched/fair: Fix that tasks are not constrained by cfs_b->quota on hotplug core, when hotplug core is offline and then online.

[Jeehong Kim]

In case that CONFIG_HOTPLUG_CPU and CONFIG_CFS_BANDWIDTH is turned on
and tasks in bandwidth controlled task group run on hotplug core,
the tasks are not controlled by cfs_b->quota when hotplug core is offline
and then online. The remaining tasks in task group consume all of
cfs_b->quota on other cores.

The cause of this problem is described as below:

1. When hotplug core is offline while tasks in task group run
on hotplug core, unregister_fair_sched_group() deletes
leaf_cfs_rq_list of tg->cfs_rq[cpu] from _of(cfs_rq)->leaf_cfs_rq_list.

2. Then, when hotplug core is online, update_runtime_enabled()
registers cfs_b->quota on cfs_rq->runtime_enabled of all leaf cfs_rq
on runqueue. However, because this is before enqueue_entity() adds
_rq->leaf_cfs_rq_list on _of(cfs_rq)->leaf_cfs_rq_list,
cfs->quota is not register on cfs_rq->runtime_enabled.

To resolve this problem, this patch makes update_runtime_enabled()
registers cfs_b->quota by using walk_tg_tree_from().

Signed-off-by: Jeehong Kim 
---
 kernel/sched/fair.c | 32 +---
 1 file changed, 21 insertions(+), 11 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 6488815..63b376d 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4373,17 +4373,27 @@ static void destroy_cfs_bandwidth(struct cfs_bandwidth 
*cfs_b)
hrtimer_cancel(_b->slack_timer);
 }

-static void __maybe_unused update_runtime_enabled(struct rq *rq)
+static int __maybe_unused __update_runtime_enabled(struct task_group *tg, void 
*data)
 {
-   struct cfs_rq *cfs_rq;
+   struct rq *rq = data;
+   struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
+   struct cfs_bandwidth *cfs_b = _rq->tg->cfs_bandwidth;

-   for_each_leaf_cfs_rq(rq, cfs_rq) {
-   struct cfs_bandwidth *cfs_b = _rq->tg->cfs_bandwidth;
+   raw_spin_lock(_b->lock);
+   cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF;
+   raw_spin_unlock(_b->lock);

-   raw_spin_lock(_b->lock);
-   cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF;
-   raw_spin_unlock(_b->lock);
-   }
+   return 0;
+}
+
+static void __maybe_unused update_runtime_enabled(struct rq *rq)
+{
+   struct cfs_rq *cfs_rq = >cfs;
+
+   /* register cfs_b->quota on the whole tg tree */
+   rcu_read_lock();
+   walk_tg_tree_from(cfs_rq->tg, __update_runtime_enabled, tg_nop, (void 
*)rq);
+   rcu_read_unlock();
 }
--

[PATCH V2] sched/fair: Fix that tasks are not constrained by cfs_b->quota on hotplug core, when hotplug core is offline and then online.

[Jeehong Kim]

In case that CONFIG_HOTPLUG_CPU and CONFIG_CFS_BANDWIDTH is turned on
and tasks in bandwidth controlled task group run on hotplug core,
the tasks are not controlled by cfs_b->quota when hotplug core is offline
and then online. The remaining tasks in task group consume all of
cfs_b->quota on other cores.

The cause of this problem is described as below:

1. When hotplug core is offline while tasks in task group run
on hotplug core, unregister_fair_sched_group() deletes
leaf_cfs_rq_list of tg->cfs_rq[cpu] from _of(cfs_rq)->leaf_cfs_rq_list.

2. Then, when hotplug core is online, update_runtime_enabled()
registers cfs_b->quota on cfs_rq->runtime_enabled of all leaf cfs_rq
on runqueue. However, because this is before enqueue_entity() adds
_rq->leaf_cfs_rq_list on _of(cfs_rq)->leaf_cfs_rq_list,
cfs->quota is not register on cfs_rq->runtime_enabled.

To resolve this problem, this patch makes update_runtime_enabled()
registers cfs_b->quota by using walk_tg_tree_from().

Signed-off-by: Jeehong Kim 
---
 kernel/sched/fair.c | 32 +---
 1 file changed, 21 insertions(+), 11 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 6488815..63b376d 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4373,17 +4373,27 @@ static void destroy_cfs_bandwidth(struct cfs_bandwidth 
*cfs_b)
hrtimer_cancel(_b->slack_timer);
 }

-static void __maybe_unused update_runtime_enabled(struct rq *rq)
+static int __maybe_unused __update_runtime_enabled(struct task_group *tg, void 
*data)
 {
-   struct cfs_rq *cfs_rq;
+   struct rq *rq = data;
+   struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
+   struct cfs_bandwidth *cfs_b = _rq->tg->cfs_bandwidth;

-   for_each_leaf_cfs_rq(rq, cfs_rq) {
-   struct cfs_bandwidth *cfs_b = _rq->tg->cfs_bandwidth;
+   raw_spin_lock(_b->lock);
+   cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF;
+   raw_spin_unlock(_b->lock);

-   raw_spin_lock(_b->lock);
-   cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF;
-   raw_spin_unlock(_b->lock);
-   }
+   return 0;
+}
+
+static void __maybe_unused update_runtime_enabled(struct rq *rq)
+{
+   struct cfs_rq *cfs_rq = >cfs;
+
+   /* register cfs_b->quota on the whole tg tree */
+   rcu_read_lock();
+   walk_tg_tree_from(cfs_rq->tg, __update_runtime_enabled, tg_nop, (void 
*)rq);
+   rcu_read_unlock();
 }
--