Re: [PATCH v4 1/4] sched/fair: Introduce primitives for CFS bandwidth burst

[Peter Zijlstra]

On Tue, Mar 16, 2021 at 12:49:28PM +0800, Huaixin Chang wrote:
> @@ -8982,6 +8983,12 @@ static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota)
>  	if (quota != RUNTIME_INF && quota > max_cfs_runtime)
>  		return -EINVAL;
>  
> +	/*
> +	 * Bound burst to defend burst against overflow during bandwidth shift.
> +	 */
> +	if (burst > max_cfs_runtime)
> +		return -EINVAL;

Why do you allow such a large burst? I would expect something like:

	if (burst > quote)
		return -EINVAL;

That limits the variance in the system. Allowing super long bursts seems
to defeat the entire purpose of bandwidth control.