2023-11-16 11:42:42

by Yiwei Lin

Subject: [PATCH] sched/fair: Update min_vruntime for reweight_entity() correctly

Since reweight_entity() may have chance to change the weight of
cfs_rq->curr entity, we should also update_min_vruntime() if
this is the case

Signed-off-by: Yiwei Lin <[email protected]>
---
kernel/sched/fair.c | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 07f555857..6fb89f4a3 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3815,17 +3815,17 @@ static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
enqueue_load_avg(cfs_rq, se);
if (se->on_rq) {
update_load_add(&cfs_rq->load, se->load.weight);
- if (!curr) {
- /*
- * The entity's vruntime has been adjusted, so let's check
- * whether the rq-wide min_vruntime needs updated too. Since
- * the calculations above require stable min_vruntime rather
- * than up-to-date one, we do the update at the end of the
- * reweight process.
- */
+ if (!curr)
__enqueue_entity(cfs_rq, se);
- update_min_vruntime(cfs_rq);
- }
+
+ /*
+ * The entity's vruntime has been adjusted, so let's check
+ * whether the rq-wide min_vruntime needs updated too. Since
+ * the calculations above require stable min_vruntime rather
+ * than up-to-date one, we do the update at the end of the
+ * reweight process.
+ */
+ update_min_vruntime(cfs_rq);
}
}

--
2.34.1

2023-11-16 11:53:03

by Abel Wu

Subject: Re: [PATCH] sched/fair: Update min_vruntime for reweight_entity() correctly

Please add a Fix tag like this:

Fixes: eab03c23c2a1 ("sched/eevdf: Fix vruntime adjustment on reweight")

On 11/16/23 7:42 PM, Yiwei Lin Wrote:
> Since reweight_entity() may have chance to change the weight of
> cfs_rq->curr entity, we should also update_min_vruntime() if
> this is the case
>
> Signed-off-by: Yiwei Lin <[email protected]>
> ---
> kernel/sched/fair.c | 20 ++++++++++----------
> 1 file changed, 10 insertions(+), 10 deletions(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 07f555857..6fb89f4a3 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -3815,17 +3815,17 @@ static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
> enqueue_load_avg(cfs_rq, se);
> if (se->on_rq) {
> update_load_add(&cfs_rq->load, se->load.weight);
> - if (!curr) {
> - /*
> - * The entity's vruntime has been adjusted, so let's check
> - * whether the rq-wide min_vruntime needs updated too. Since
> - * the calculations above require stable min_vruntime rather
> - * than up-to-date one, we do the update at the end of the
> - * reweight process.
> - */
> + if (!curr)
> __enqueue_entity(cfs_rq, se);
> - update_min_vruntime(cfs_rq);
> - }
> +
> + /*
> + * The entity's vruntime has been adjusted, so let's check
> + * whether the rq-wide min_vruntime needs updated too. Since
> + * the calculations above require stable min_vruntime rather
> + * than up-to-date one, we do the update at the end of the
> + * reweight process.
> + */
> + update_min_vruntime(cfs_rq);
> }
> }
>

LGTM, thanks!

2023-11-17 07:34:51

by Abel Wu

Subject: Re: [PATCH] sched/fair: Update min_vruntime for reweight_entity() correctly

On 11/16/23 7:52 PM, Abel Wu Wrote:
> Please add a Fix tag like this:
>
> Fixes: eab03c23c2a1 ("sched/eevdf: Fix vruntime adjustment on reweight")

Can you resend this patch with this fix tag please?

>
> On 11/16/23 7:42 PM, Yiwei Lin Wrote:
>> Since reweight_entity() may have chance to change the weight of
>> cfs_rq->curr entity, we should also update_min_vruntime() if
>> this is the case
>>
>> Signed-off-by: Yiwei Lin <[email protected]>
>> ---
>>   kernel/sched/fair.c | 20 ++++++++++----------
>>   1 file changed, 10 insertions(+), 10 deletions(-)
>>
>> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
>> index 07f555857..6fb89f4a3 100644
>> --- a/kernel/sched/fair.c
>> +++ b/kernel/sched/fair.c
>> @@ -3815,17 +3815,17 @@ static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
>>       enqueue_load_avg(cfs_rq, se);
>>       if (se->on_rq) {
>>           update_load_add(&cfs_rq->load, se->load.weight);
>> -        if (!curr) {
>> -            /*
>> -             * The entity's vruntime has been adjusted, so let's check
>> -             * whether the rq-wide min_vruntime needs updated too. Since
>> -             * the calculations above require stable min_vruntime rather
>> -             * than up-to-date one, we do the update at the end of the
>> -             * reweight process.
>> -             */
>> +        if (!curr)
>>               __enqueue_entity(cfs_rq, se);
>> -            update_min_vruntime(cfs_rq);
>> -        }
>> +
>> +        /*
>> +         * The entity's vruntime has been adjusted, so let's check
>> +         * whether the rq-wide min_vruntime needs updated too. Since
>> +         * the calculations above require stable min_vruntime rather
>> +         * than up-to-date one, we do the update at the end of the
>> +         * reweight process.
>> +         */
>> +        update_min_vruntime(cfs_rq);
>>       }
>>   }
>
> LGTM, thanks!