Re: [PATCH v2 06/23] sched/cache: Track LLC-preferred tasks per runqueue

[Peter Zijlstra]

On Wed, Dec 03, 2025 at 03:07:25PM -0800, Tim Chen wrote:


>  #ifdef CONFIG_SCHED_CACHE
>  	struct callback_head		cache_work;
> +	/*the p is currently refcounted in a rq's preferred llc stats*/

Shall we have spaces after and before the comment marks?

Also, comment confuses me, I don't see get_task_struct() /
put_task_struct() usage. Did you mean something else with refcount?

> +	bool				sched_llc_active;
>  	int				preferred_llc;
>  #endif

> +static void account_llc_dequeue(struct rq *rq, struct task_struct *p)
> +{
> +	int pref_llc;
> +
> +	/*
> +	 * Borrow the uc_se->active from uclamp_rq_inc_id(),
> +	 * uclamp_rq_dec_id() to avoid the unbalanced calculation
> +	 * of rq statistics.
> +	 */
> +	if (unlikely(!p->sched_llc_active))
> +		return;

Another very confusing comment; what? Also, can you please explain (in
the new comment) how we get here without having llc_active set?

> +
> +	pref_llc = p->preferred_llc;
> +	if (pref_llc < 0)
> +		return;
> +
> +	rq->nr_llc_running--;
> +	rq->nr_pref_llc_running -= (pref_llc == task_llc(p));
> +	p->sched_llc_active = false;
> +}