RE: [PATCH] sched/fair: fix pick_eevdf to always find the correct se

[Biju Das]

Hi Peter Zijlstra,


> Subject: Re: [PATCH] sched/fair: fix pick_eevdf to always find the correct
> se
> 
> On Fri, Oct 06, 2023 at 05:55:01PM +0200, Peter Zijlstra wrote:
> 
> > And yeah, min_deadline is hosed somehow.
> >
> > migration/28-185     [028] d..2.    70.264274: validate_cfs_rq: --- /
> > migration/28-185     [028] d..2.    70.264277: __print_se:
> ffff88845cf48080 w: 1024 ve: -58857638 lag: 870381 vd: -55861854 vmd: -
> 66302085 E (11372/tr)
> > migration/28-185     [028] d..2.    70.264280: __print_se:
> ffff88810d165800 w: 25 ve: -80323686 lag: 22336429 vd: -41496434 vmd: -
> 66302085 E (-1//autogroup-31)
> > migration/28-185     [028] d..2.    70.264282: __print_se:
> ffff888108379000 w: 25 ve: 0 lag: -57987257 vd: 114632828 vmd: 114632828 N
> (-1//autogroup-33)
> > migration/28-185     [028] d..2.    70.264283: validate_cfs_rq:
> min_deadline: -55861854 avg_vruntime: -62278313462 / 1074 = -57987256
> >
> > I need to go make dinner (kids hungry), but I'll see if I can figure
> > out how this happens...
> 
> *sigh*, does the below help?

I confirm the message "EEVDF scheduling fail, picking leftmost" is not appearing with this patch.

Cheers,
Biju
> 
> ---
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index
> 04fbcbda97d5..6a670f119efa 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -3632,6 +3747,7 @@ static void reweight_entity(struct cfs_rq *cfs_rq,
> struct sched_entity *se,
>  		 */
>  		deadline = div_s64(deadline * old_weight, weight);
>  		se->deadline = se->vruntime + deadline;
> +		min_deadline_cb_propagate(&se->run_node, NULL);
>  	}
> 
>  #ifdef CONFIG_SMP