2023-11-17 08:01:49

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

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

2023-11-17 08:07:17

by Abel Wu

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

On 11/17/23 4:01 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
>
> Fixes: eab03c23c2a1 ("sched/eevdf: Fix vruntime adjustment on reweight")
> 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);
> }
> }
>

Reviewed-by: Abel Wu <[email protected]>

Thanks!

2023-11-20 11:49:05

by Peter Zijlstra

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

On Fri, Nov 17, 2023 at 04:01:06PM +0800, 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
>
> Fixes: eab03c23c2a1 ("sched/eevdf: Fix vruntime adjustment on reweight")
> Signed-off-by: Yiwei Lin <[email protected]>


Right, but as you wrote in your other patch, min_vruntime isn't all that
critical anymore. I'll go queue this in sched/core, I don't think this
warrants /urgent.

> ---
> 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
>

2023-11-29 14:56:14

by tip-bot2 for Jacob Pan

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

The following commit has been merged into the sched/core branch of tip:

Commit-ID: 5068d84054b766efe7c6202fc71b2350d1c326f1
Gitweb: https://git.kernel.org/tip/5068d84054b766efe7c6202fc71b2350d1c326f1
Author: Yiwei Lin <[email protected]>
AuthorDate: Fri, 17 Nov 2023 16:01:06 +08:00
Committer: Peter Zijlstra <[email protected]>
CommitterDate: Wed, 29 Nov 2023 15:43:52 +01:00

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

Fixes: eab03c23c2a1 ("sched/eevdf: Fix vruntime adjustment on reweight")
Signed-off-by: Yiwei Lin <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Reviewed-by: Abel Wu <[email protected]>
Link: https://lore.kernel.org/r/[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 34fe6e9..bcea3d5 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);
}
}