Re: [PATCH v5 6/7] sched/deadline: Deferrable dl server

[Peter Zijlstra]

On Sat, Nov 04, 2023 at 11:59:23AM +0100, Daniel Bristot de Oliveira wrote:

> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index b15f7f376a67..399237cd9f59 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -1201,6 +1201,8 @@ static void update_curr(struct cfs_rq *cfs_rq)
>  		account_group_exec_runtime(curtask, delta_exec);
>  		if (curtask->server)
>  			dl_server_update(curtask->server, delta_exec);
> +		else
> +			dl_server_update(&rq_of(cfs_rq)->fair_server, delta_exec);
>  	}
>  
>  	account_cfs_rq_runtime(cfs_rq, delta_exec);

I've rewritten that something like so..

--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1182,12 +1182,13 @@ s64 update_curr_common(struct rq *rq)
 static void update_curr(struct cfs_rq *cfs_rq)
 {
 	struct sched_entity *curr = cfs_rq->curr;
+	struct rq *rq = rq_of(cfs_rq);
 	s64 delta_exec;
 
 	if (unlikely(!curr))
 		return;
 
-	delta_exec = update_curr_se(rq_of(cfs_rq), curr);
+	delta_exec = update_curr_se(rq, curr);
 	if (unlikely(delta_exec <= 0))
 		return;
 
@@ -1195,8 +1196,17 @@ static void update_curr(struct cfs_rq *c
 	update_deadline(cfs_rq, curr);
 	update_min_vruntime(cfs_rq);
 
-	if (entity_is_task(curr))
-		update_curr_task(task_of(curr), delta_exec);
+	if (entity_is_task(curr)) {
+		struct task_struct *p = task_of(curr);
+		update_curr_task(p, delta_exec);
+		/*
+		 * Any fair task that runs outside of fair_server should
+		 * account against fair_server such that it can account for
+		 * this time and possible avoid running this period.
+		 */
+		if (p->dl_server != &rq->fair_server)
+			dl_server_update(&rq->fair_server, delta_exec);
+	}
 
 	account_cfs_rq_runtime(cfs_rq, delta_exec);
 }