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 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 >> &rq_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 >> &rq_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 >> &cfs_rq->leaf_cfs_rq_list on &rq_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 = &cfs_rq->tg->cfs_bandwidth; >> >> +raw_spin_lock(&cfs_b->lock); >> +raw_spin_unlock(&cfs_b->lock); >> >> +return 0; >> +} >> + >> +static void __maybe_unused update_runtime_enabled(struct rq *rq) >> +{ >> +struct cfs_rq *cfs_rq = &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.
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 &rq_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 &rq_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 > &cfs_rq->leaf_cfs_rq_list on &rq_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 = &cfs_rq->tg->cfs_bandwidth; > > +raw_spin_lock(&cfs_b->lock); > +raw_spin_unlock(&cfs_b->lock); > > +return 0; > +} > + > +static void __maybe_unused update_runtime_enabled(struct rq *rq) > +{ > +struct cfs_rq *cfs_rq = &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 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 &rq_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 &rq_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 &cfs_rq->leaf_cfs_rq_list on &rq_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 = &cfs_rq->tg->cfs_bandwidth; +raw_spin_lock(&cfs_b->lock); +raw_spin_unlock(&cfs_b->lock); +return 0; +} + +static void __maybe_unused update_runtime_enabled(struct rq *rq) +{ +struct cfs_rq *cfs_rq = &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.
>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 &rq_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 &rq_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 >>> &cfs_rq->leaf_cfs_rq_list on &rq_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 = &cfs_rq->tg->cfs_bandwidth; >>> >>> +raw_spin_lock(&cfs_b->lock); >>> +raw_spin_unlock(&cfs_b->lock); >>> >>> +return 0; >>> +} >>> + >>> +static void __maybe_unused update_runtime_enabled(struct rq *rq) >>> +{ >>> +struct cfs_rq *cfs_rq = &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.
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 &rq_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 >> &cfs_rq->leaf_cfs_rq_list on &rq_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 = &cfs_rq->tg->cfs_bandwidth; >> >> +raw_spin_lock(&cfs_b->lock); >> +cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF; >> +raw_spin_unlock(&cfs_b->lock); >> >> +return 0; >> +} >> + >> +static void __maybe_unused update_runtime_enabled(struct rq *rq) >> +{ >> +struct cfs_rq *cfs_rq = &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.
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 &rq_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 >> &cfs_rq->leaf_cfs_rq_list on &rq_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 = &cfs_rq->tg->cfs_bandwidth; >> >> +raw_spin_lock(&cfs_b->lock); >> +cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF; >> +raw_spin_unlock(&cfs_b->lock); >> >> +return 0; >> +} >> + >> +static void __maybe_unused update_runtime_enabled(struct rq *rq) >> +{ >> +struct cfs_rq *cfs_rq = &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.
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 &rq_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 > &cfs_rq->leaf_cfs_rq_list on &rq_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 = &cfs_rq->tg->cfs_bandwidth; > > + raw_spin_lock(&cfs_b->lock); > + cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF; > + raw_spin_unlock(&cfs_b->lock); > > + return 0; > +} > + > +static void __maybe_unused update_runtime_enabled(struct rq *rq) > +{ > + struct cfs_rq *cfs_rq = &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.
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 &rq_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 &cfs_rq->leaf_cfs_rq_list on &rq_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(&cfs_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 = &cfs_rq->tg->cfs_bandwidth; - for_each_leaf_cfs_rq(rq, cfs_rq) { - struct cfs_bandwidth *cfs_b = &cfs_rq->tg->cfs_bandwidth; + raw_spin_lock(&cfs_b->lock); + cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF; + raw_spin_unlock(&cfs_b->lock); - raw_spin_lock(&cfs_b->lock); - cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF; - raw_spin_unlock(&cfs_b->lock); - } + return 0; +} + +static void __maybe_unused update_runtime_enabled(struct rq *rq) +{ + struct cfs_rq *cfs_rq = &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.
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 &rq_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 &cfs_rq->leaf_cfs_rq_list on &rq_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(&cfs_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 = &cfs_rq->tg->cfs_bandwidth; - for_each_leaf_cfs_rq(rq, cfs_rq) { - struct cfs_bandwidth *cfs_b = &cfs_rq->tg->cfs_bandwidth; + raw_spin_lock(&cfs_b->lock); + cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF; + raw_spin_unlock(&cfs_b->lock); - raw_spin_lock(&cfs_b->lock); - cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF; - raw_spin_unlock(&cfs_b->lock); - } + return 0; +} + +static void __maybe_unused update_runtime_enabled(struct rq *rq) +{ + struct cfs_rq *cfs_rq = &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(); } --