Messages in this thread | | | From | Benjamin Segall <> | Subject | Re: [PATCH v5 1/2] sched, cgroup: Restore meaning to hierarchical_quota | Date | Mon, 10 Jul 2023 17:00:11 -0700 |
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Phil Auld <pauld@redhat.com> writes:
> In cgroupv2 cfs_b->hierarchical_quota is set to -1 for all task > groups due to the previous fix simply taking the min. It should > reflect a limit imposed at that level or by an ancestor. Even > though cgroupv2 does not require child quota to be less than or > equal to that of its ancestors the task group will still be > constrained by such a quota so this should be shown here. Cgroupv1 > continues to set this correctly. > > In both cases, add initialization when a new task group is created > based on the current parent's value (or RUNTIME_INF in the case of > root_task_group). Otherwise, the field is wrong until a quota is > changed after creation and __cfs_schedulable() is called.
Reviewed-by: Ben Segall <bsegall@google.com>
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index a68d1276bab0..1b214e10c25d 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -11038,11 +11038,14 @@ static int tg_cfs_schedulable_down(struct task_group *tg, void *data) > > /* > * Ensure max(child_quota) <= parent_quota. On cgroup2, > - * always take the min. On cgroup1, only inherit when no > - * limit is set: > + * always take the non-RUNTIME_INF min. On cgroup1, only > + * inherit when no limit is set: > */ > if (cgroup_subsys_on_dfl(cpu_cgrp_subsys)) { > - quota = min(quota, parent_quota); > + if (quota == RUNTIME_INF) > + quota = parent_quota; > + else if (parent_quota != RUNTIME_INF) > + quota = min(quota, parent_quota); > } else { > if (quota == RUNTIME_INF) > quota = parent_quota;
I suppose you could also set RUNTIME_INF to be a positive value or better yet just compare at unsigned, but it's not like config needs to be fast, so no need to mess with that.
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 373ff5f55884..92381f9ecf37 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -6005,13 +6005,14 @@ static enum hrtimer_restart sched_cfs_period_timer(struct hrtimer *timer) > return idle ? HRTIMER_NORESTART : HRTIMER_RESTART; > } > > -void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) > +void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b, struct cfs_bandwidth *parent) > { > raw_spin_lock_init(&cfs_b->lock); > cfs_b->runtime = 0; > cfs_b->quota = RUNTIME_INF; > cfs_b->period = ns_to_ktime(default_cfs_period()); > cfs_b->burst = 0; > + cfs_b->hierarchical_quota = ((parent) ? parent->hierarchical_quota : RUNTIME_INF);
Minor style nit: don't need any of these parens here.
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