Re: [RFC PATCH v2 1/7] sched/fair: Add related data structure for task based throttle

K Prateek Nayak
2025-04-14T03:58:48Z

Hello Aaron,

On 4/9/2025 5:37 PM, Aaron Lu wrote:
> From: Valentin Schneider <vschneid@redhat.com>
>
> Add related data structures for this new throttle functionality.
>
> Signed-off-by: Valentin Schneider <vschneid@redhat.com>
> Signed-off-by: Aaron Lu <ziqianlu@bytedance.com>
> ---
> include/linux/sched.h | 4 ++++
> kernel/sched/core.c | 3 +++
> kernel/sched/fair.c | 12 ++++++++++++
> kernel/sched/sched.h | 2 ++
> 4 files changed, 21 insertions(+)
>
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index f96ac19828934..0b55c79fee209 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -880,6 +880,10 @@ struct task_struct {
>
> #ifdef CONFIG_CGROUP_SCHED
> struct task_group *sched_task_group;
> +#ifdef CONFIG_CFS_BANDWIDTH
> + struct callback_head sched_throttle_work;
> + struct list_head throttle_node;

Since throttled tasks are fully dequeued before placing on the
"throttled_limbo_list", is it possible to reuse "p->se.group_node"?

Currently, it is used to track the task on "rq->cfs_tasks" and during
load-balancing when moving a bunch of tasks between CPUs but since a
fully throttled task is not tracked by either, it should be safe to
reuse this bit (CONFIG_DEBUG_LIST will scream if I'm wrong) and save
up on some space in the task_struct.

Thoughts?

--
Thanks and Regards,
Prateek

> +#endif
> #endif
>