Re: [PATCH 5/8] sched/eevdf: Reset lag when waking up on idle cpu

[Kayra Cizmeci <kayracizmeci@gmail.com>]

Hi Vincent,

> @@ -908,18 +908,25 @@ void decay_entity_lag(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
>  	if (vlag <= 0)
>  		return;
>  
> -	if (flags & ENQUEUE_MIGRATED)
> -		return;
> +	rq = rq_of(cfs_rq);
>  
> -	/* Compute the sleep time */
> -	delta_exec = rq_clock_task(rq_of(cfs_rq)) - se->exec_start;
> -	if (unlikely(delta_exec <= 0))
> -		return;
> +	if (rq->curr == rq->idle) {
> +		/* You can't claim any lag when waking on idle CPU */
> +		vlag = 0;
> +	} else if (!(flags & ENQUEUE_MIGRATED)) {
> +		u64 now = rq_clock_task(rq);
> +		s64 delta_exec;
>  
> -	vlag -= calc_delta_fair(delta_exec, se);
> +		/* Compute the sleep time */
> +		delta_exec = now - se->exec_start;
> +		if (unlikely(delta_exec <= 0))
> +			return;
>  
> -	/* vlag can't become negative while sleeping */
> -	se->vlag = max(0, vlag);
> +		vlag -= calc_delta_fair(delta_exec, se);
> +
> +		/* vlag can't become neg while sleeping */
> +		se->vlag = max(0, vlag);
> +	}
>  }

When if (rq->curr == rq->idle) runs the else if does not. So on that branch
we just set local vlag to 0. I think you wanted to set se->vlag to 0?


Thanks,
Kayra :>