Messages in this thread Patch in this message |  | | Date | Mon, 28 Mar 2022 11:24:09 +0200 | Subject | Re: [RFC 5/6] sched/fair: Take into account latency nice at wakeup | From | Dietmar Eggemann <> |
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On 11/03/2022 17:14, Vincent Guittot wrote:
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> @@ -4412,7 +4417,7 @@ int sched_fork(unsigned long clone_flags, struct task_struct *p) > p->prio = p->normal_prio = p->static_prio; > set_load_weight(p, false); > > - p->latency_nice = DEFAULT_LATENCY_NICE; > + p->latency_prio = NICE_TO_LATENCY(0); > /* > * We don't need the reset flag anymore after the fork. It has > * fulfilled its duty: > @@ -4420,6 +4425,9 @@ int sched_fork(unsigned long clone_flags, struct task_struct *p) > p->sched_reset_on_fork = 0; > } > > + /* Once latency_prio is set, update the latency weight */ > + set_latency_weight(p);
I thought we only have to do this in the `sched_reset_on_fork` case? Like we do with set_load_weight(). Can we not rely on dup_task_struct() in the other case?
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> @@ -5648,6 +5677,9 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) > if (!task_new) > update_overutilized_status(rq); > > + if (rq->curr == rq->idle) > + check_preempt_from_idle(cfs_rq_of(&p->se), &p->se);
This is done here (1) because check_preempt_wakeup() (2) is only called if p and rq->curr have CFS sched class?
ttwu_do_activate() activate_task() enqueue_task <-- (1) ttwu_do_wakeup() check_preempt_curr() if (p->sched_class == rq->curr->sched_class) rq->curr->sched_class->check_preempt_curr() <-- (2)
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> @@ -7008,6 +7059,10 @@ static int > wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se) > { > s64 gran, vdiff = curr->vruntime - se->vruntime; > + int latency_weight = se->latency_weight - curr->latency_weight; > + > + latency_weight = min(latency_weight, se->latency_weight);
Why the min out of latency_weight_diff(se, curr) and se->latency_weight here?
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