Messages in this thread | ![/](/images/icornerl.gif) | | Date | Tue, 11 Jul 2023 09:13:41 -0400 | From | Phil Auld <> | Subject | Re: [PATCH v5 1/2] sched, cgroup: Restore meaning to hierarchical_quota |
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On Mon, Jul 10, 2023 at 05:00:11PM -0700 Benjamin Segall wrote: > 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> >
Thanks, I'll hold on to this for the next version where I update the comment if that's okay. I was just going to send that but based on your comment on patch 2 may just do a v6 of the whole thing.
Cheers, Phil
> > 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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