Re: [PATCH v5 1/2] sched, cgroup: Restore meaning to hierarchical_quota

Tejun Heo
2023-07-10T20:17:15Z

Hello,

On Fri, Jul 07, 2023 at 03:57:47PM -0400, Phil Auld wrote:
> @@ -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);

Can you please add a comment explaining how hierarchical_quota is used in
cgroup2? It seems like you're using it to detect whether bw limit is
enforced for a given cgroup, which is fine, but the above code in isolation
looks a bit curious because it doesn't serve any purpose by itself.

Thanks.

--
tejun