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

[Tejun Heo]

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