kernel/sched/fair.c | 24 ++++++++++++++++-------- 1 file changed, 16 insertions(+), 8 deletions(-)
From: pugaowei <pugaowei@oppo.com>
we should update the weight of cfs_rq before update_cfs_group().
Ensure that we can get accurate shares of the cfs_rq when its
weights changes. we can find this work was done correctly in
dequeue_entity(). so fix it.
patch_V1 :
https://lore.kernel.org/lkml/20240531030833.3375-1-pugaowei@oppo.com/T/#u
trigger a warnning below because of the changing order of
account_entity_enqueue().
[ 0.400603][ T0] ? __warn (kernel/panic.c:693)
[ 0.400603][ T0] ? place_entity (kernel/sched/fair.c:5256 (discriminator 1))
[ 0.400603][ T0] ? report_bug (lib/bug.c:180 lib/bug.c:219)
[ 0.400603][ T0] ? handle_bug (arch/x86/kernel/traps.c:239)
[ 0.400603][ T0] ? exc_invalid_op (arch/x86/kernel/traps.c:260 (discriminator 1))
[ 0.400603][ T0] ? asm_exc_invalid_op (arch/x86/include/asm/idtentry.h:621)
[ 0.400603][ T0] ? place_entity (kernel/sched/fair.c:5256 (discriminator 1))
[ 0.400603][ T0] ? place_entity (kernel/sched/fair.c:5182)
[ 0.400603][ T0] enqueue_entity (kernel/sched/fair.c:5328)
[ 0.400603][ T0] enqueue_task_fair (kernel/sched/fair.c:6785)
V2 fix the warnning and keep the lag without inflating it when it is
the first sched_entity queued on the cfs_rq.
Signed-off-by: pugaowei <pugaowei@oppo.com>
---
kernel/sched/fair.c | 24 ++++++++++++++++--------
1 file changed, 16 insertions(+), 8 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 8a5b1ae0aa55..2fb1fbcfdda3 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5190,12 +5190,12 @@ place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
*
* EEVDF: placement strategy #1 / #2
*/
- if (sched_feat(PLACE_LAG) && cfs_rq->nr_running) {
+ if (sched_feat(PLACE_LAG)) {
struct sched_entity *curr = cfs_rq->curr;
- unsigned long load;
+ unsigned long load, se_load;
lag = se->vlag;
-
+ se_load = scale_load_down(se->load.weight);
/*
* If we want to place a task and preserve lag, we have to
* consider the effect of the new entity on the weighted
@@ -5252,9 +5252,13 @@ place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
if (curr && curr->on_rq)
load += scale_load_down(curr->load.weight);
- lag *= load + scale_load_down(se->load.weight);
- if (WARN_ON_ONCE(!load))
- load = 1;
+ lag *= load + se_load;
+ /*
+ * we just need to keep the lag whithout inflating it when the se is
+ * the first sched_entity queued on cfs_rq.
+ */
+ if (!load)
+ load = se_load;
lag = div_s64(lag, load);
}
@@ -5304,6 +5308,12 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
*/
update_load_avg(cfs_rq, se, UPDATE_TG | DO_ATTACH);
se_update_runnable(se);
+
+ /*
+ * we should update the weight of cfs_rq before update_cfs_group.
+ * Ensure we can get accurate shares of the cfs_rq when its weights changes.
+ */
+ account_entity_enqueue(cfs_rq, se);
/*
* XXX update_load_avg() above will have attached us to the pelt sum;
* but update_cfs_group() here will re-adjust the weight and have to
@@ -5318,8 +5328,6 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
if (!curr)
place_entity(cfs_rq, se, flags);
- account_entity_enqueue(cfs_rq, se);
-
/* Entity has migrated, no longer consider this task hot */
if (flags & ENQUEUE_MIGRATED)
se->exec_start = 0;
--
2.17.1On Mon, 3 Jun 2024 at 11:18, Gaowei.Pu <pugaowei@oppo.com> wrote:
>
> From: pugaowei <pugaowei@oppo.com>
>
> we should update the weight of cfs_rq before update_cfs_group().
update_cfs_group() updates the weight of se that is about to be
enqueued on cfs_rq so the current order looks good for me:
update_cfs_group()
reweight_entity(cfs_rq, se, shares); //se->on_rq == 0
update_load_set(&se->load, weight);
se->load.weight = weight
account_entity_enqueue(cfs_rq, se);
update_load_add(&cfs_rq->load, se->load.weight);
cfs_rq->load.weight += se->load.weight
Have you faced some problems in particular ?
> Ensure that we can get accurate shares of the cfs_rq when its
> weights changes. we can find this work was done correctly in
> dequeue_entity(). so fix it.
>
> patch_V1 :
> https://lore.kernel.org/lkml/20240531030833.3375-1-pugaowei@oppo.com/T/#u
> trigger a warnning below because of the changing order of
> account_entity_enqueue().
>
> [ 0.400603][ T0] ? __warn (kernel/panic.c:693)
>
> [ 0.400603][ T0] ? place_entity (kernel/sched/fair.c:5256 (discriminator 1))
>
> [ 0.400603][ T0] ? report_bug (lib/bug.c:180 lib/bug.c:219)
>
> [ 0.400603][ T0] ? handle_bug (arch/x86/kernel/traps.c:239)
>
> [ 0.400603][ T0] ? exc_invalid_op (arch/x86/kernel/traps.c:260 (discriminator 1))
>
> [ 0.400603][ T0] ? asm_exc_invalid_op (arch/x86/include/asm/idtentry.h:621)
>
> [ 0.400603][ T0] ? place_entity (kernel/sched/fair.c:5256 (discriminator 1))
>
> [ 0.400603][ T0] ? place_entity (kernel/sched/fair.c:5182)
>
> [ 0.400603][ T0] enqueue_entity (kernel/sched/fair.c:5328)
>
> [ 0.400603][ T0] enqueue_task_fair (kernel/sched/fair.c:6785)
>
> V2 fix the warnning and keep the lag without inflating it when it is
> the first sched_entity queued on the cfs_rq.
>
> Signed-off-by: pugaowei <pugaowei@oppo.com>
> ---
> kernel/sched/fair.c | 24 ++++++++++++++++--------
> 1 file changed, 16 insertions(+), 8 deletions(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 8a5b1ae0aa55..2fb1fbcfdda3 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -5190,12 +5190,12 @@ place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
> *
> * EEVDF: placement strategy #1 / #2
> */
> - if (sched_feat(PLACE_LAG) && cfs_rq->nr_running) {
> + if (sched_feat(PLACE_LAG)) {
> struct sched_entity *curr = cfs_rq->curr;
> - unsigned long load;
> + unsigned long load, se_load;
>
> lag = se->vlag;
> -
> + se_load = scale_load_down(se->load.weight);
> /*
> * If we want to place a task and preserve lag, we have to
> * consider the effect of the new entity on the weighted
> @@ -5252,9 +5252,13 @@ place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
> if (curr && curr->on_rq)
> load += scale_load_down(curr->load.weight);
>
> - lag *= load + scale_load_down(se->load.weight);
> - if (WARN_ON_ONCE(!load))
> - load = 1;
> + lag *= load + se_load;
> + /*
> + * we just need to keep the lag whithout inflating it when the se is
> + * the first sched_entity queued on cfs_rq.
> + */
> + if (!load)
> + load = se_load;
> lag = div_s64(lag, load);
> }
>
> @@ -5304,6 +5308,12 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
> */
> update_load_avg(cfs_rq, se, UPDATE_TG | DO_ATTACH);
> se_update_runnable(se);
> +
> + /*
> + * we should update the weight of cfs_rq before update_cfs_group.
> + * Ensure we can get accurate shares of the cfs_rq when its weights changes.
> + */
> + account_entity_enqueue(cfs_rq, se);
> /*
> * XXX update_load_avg() above will have attached us to the pelt sum;
> * but update_cfs_group() here will re-adjust the weight and have to
> @@ -5318,8 +5328,6 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
> if (!curr)
> place_entity(cfs_rq, se, flags);
>
> - account_entity_enqueue(cfs_rq, se);
> -
> /* Entity has migrated, no longer consider this task hot */
> if (flags & ENQUEUE_MIGRATED)
> se->exec_start = 0;
> --
> 2.17.1
>
Hi vincent,
On 2024/6/11 18:59, Vincent Guittot wrote:
> On Mon, 3 Jun 2024 at 11:18, Gaowei.Pu <pugaowei@oppo.com> wrote:
>>
>> From: pugaowei <pugaowei@oppo.com>
>>
>> we should update the weight of cfs_rq before update_cfs_group().
>
> update_cfs_group() updates the weight of se that is about to be
> enqueued on cfs_rq so the current order looks good for me:
>
> update_cfs_group()
> reweight_entity(cfs_rq, se, shares); //se->on_rq == 0
> update_load_set(&se->load, weight);
> se->load.weight = weight
>
> account_entity_enqueue(cfs_rq, se);
> update_load_add(&cfs_rq->load, se->load.weight);
> cfs_rq->load.weight += se->load.weight
>
> Have you faced some problems in particular ?
sorry, made a mistask.
account_entity_enqueue(cfs_rq, se) updates weight of cfs_rq on which entity queued.
update_cfs_group(se) updates weight of the cfs_rq owned by the entity. so there is no conflict
or running order problem.
thanks for your reply~
>
>> Ensure that we can get accurate shares of the cfs_rq when its
>> weights changes. we can find this work was done correctly in
>> dequeue_entity(). so fix it.
>>
>> patch_V1 :
>> https://lore.kernel.org/lkml/20240531030833.3375-1-pugaowei@oppo.com/T/#u
>> trigger a warnning below because of the changing order of
>> account_entity_enqueue().
>>
>> [ 0.400603][ T0] ? __warn (kernel/panic.c:693)
>>
>> [ 0.400603][ T0] ? place_entity (kernel/sched/fair.c:5256 (discriminator 1))
>>
>> [ 0.400603][ T0] ? report_bug (lib/bug.c:180 lib/bug.c:219)
>>
>> [ 0.400603][ T0] ? handle_bug (arch/x86/kernel/traps.c:239)
>>
>> [ 0.400603][ T0] ? exc_invalid_op (arch/x86/kernel/traps.c:260 (discriminator 1))
>>
>> [ 0.400603][ T0] ? asm_exc_invalid_op (arch/x86/include/asm/idtentry.h:621)
>>
>> [ 0.400603][ T0] ? place_entity (kernel/sched/fair.c:5256 (discriminator 1))
>>
>> [ 0.400603][ T0] ? place_entity (kernel/sched/fair.c:5182)
>>
>> [ 0.400603][ T0] enqueue_entity (kernel/sched/fair.c:5328)
>>
>> [ 0.400603][ T0] enqueue_task_fair (kernel/sched/fair.c:6785)
>>
>> V2 fix the warnning and keep the lag without inflating it when it is
>> the first sched_entity queued on the cfs_rq.
>>
>> Signed-off-by: pugaowei <pugaowei@oppo.com>
>> ---
>> kernel/sched/fair.c | 24 ++++++++++++++++--------
>> 1 file changed, 16 insertions(+), 8 deletions(-)
>>
>> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
>> index 8a5b1ae0aa55..2fb1fbcfdda3 100644
>> --- a/kernel/sched/fair.c
>> +++ b/kernel/sched/fair.c
>> @@ -5190,12 +5190,12 @@ place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
>> *
>> * EEVDF: placement strategy #1 / #2
>> */
>> - if (sched_feat(PLACE_LAG) && cfs_rq->nr_running) {
>> + if (sched_feat(PLACE_LAG)) {
>> struct sched_entity *curr = cfs_rq->curr;
>> - unsigned long load;
>> + unsigned long load, se_load;
>>
>> lag = se->vlag;
>> -
>> + se_load = scale_load_down(se->load.weight);
>> /*
>> * If we want to place a task and preserve lag, we have to
>> * consider the effect of the new entity on the weighted
>> @@ -5252,9 +5252,13 @@ place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
>> if (curr && curr->on_rq)
>> load += scale_load_down(curr->load.weight);
>>
>> - lag *= load + scale_load_down(se->load.weight);
>> - if (WARN_ON_ONCE(!load))
>> - load = 1;
>> + lag *= load + se_load;
>> + /*
>> + * we just need to keep the lag whithout inflating it when the se is
>> + * the first sched_entity queued on cfs_rq.
>> + */
>> + if (!load)
>> + load = se_load;
>> lag = div_s64(lag, load);
>> }
>>
>> @@ -5304,6 +5308,12 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
>> */
>> update_load_avg(cfs_rq, se, UPDATE_TG | DO_ATTACH);
>> se_update_runnable(se);
>> +
>> + /*
>> + * we should update the weight of cfs_rq before update_cfs_group.
>> + * Ensure we can get accurate shares of the cfs_rq when its weights changes.
>> + */
>> + account_entity_enqueue(cfs_rq, se);
>> /*
>> * XXX update_load_avg() above will have attached us to the pelt sum;
>> * but update_cfs_group() here will re-adjust the weight and have to
>> @@ -5318,8 +5328,6 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
>> if (!curr)
>> place_entity(cfs_rq, se, flags);
>>
>> - account_entity_enqueue(cfs_rq, se);
>> -
>> /* Entity has migrated, no longer consider this task hot */
>> if (flags & ENQUEUE_MIGRATED)
>> se->exec_start = 0;
>> --
>> 2.17.1
>>
ping...
On 2024/6/3 17:18, Gaowei.Pu wrote:
> From: pugaowei <pugaowei@oppo.com>
>
> we should update the weight of cfs_rq before update_cfs_group().
> Ensure that we can get accurate shares of the cfs_rq when its
> weights changes. we can find this work was done correctly in
> dequeue_entity(). so fix it.
>
> patch_V1 :
> https://lore.kernel.org/lkml/20240531030833.3375-1-pugaowei@oppo.com/T/#u
> trigger a warnning below because of the changing order of
> account_entity_enqueue().
>
> [ 0.400603][ T0] ? __warn (kernel/panic.c:693)
>
> [ 0.400603][ T0] ? place_entity (kernel/sched/fair.c:5256 (discriminator 1))
>
> [ 0.400603][ T0] ? report_bug (lib/bug.c:180 lib/bug.c:219)
>
> [ 0.400603][ T0] ? handle_bug (arch/x86/kernel/traps.c:239)
>
> [ 0.400603][ T0] ? exc_invalid_op (arch/x86/kernel/traps.c:260 (discriminator 1))
>
> [ 0.400603][ T0] ? asm_exc_invalid_op (arch/x86/include/asm/idtentry.h:621)
>
> [ 0.400603][ T0] ? place_entity (kernel/sched/fair.c:5256 (discriminator 1))
>
> [ 0.400603][ T0] ? place_entity (kernel/sched/fair.c:5182)
>
> [ 0.400603][ T0] enqueue_entity (kernel/sched/fair.c:5328)
>
> [ 0.400603][ T0] enqueue_task_fair (kernel/sched/fair.c:6785)
>
> V2 fix the warnning and keep the lag without inflating it when it is
> the first sched_entity queued on the cfs_rq.
>
> Signed-off-by: pugaowei <pugaowei@oppo.com>
> ---
> kernel/sched/fair.c | 24 ++++++++++++++++--------
> 1 file changed, 16 insertions(+), 8 deletions(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 8a5b1ae0aa55..2fb1fbcfdda3 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -5190,12 +5190,12 @@ place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
> *
> * EEVDF: placement strategy #1 / #2
> */
> - if (sched_feat(PLACE_LAG) && cfs_rq->nr_running) {
> + if (sched_feat(PLACE_LAG)) {
> struct sched_entity *curr = cfs_rq->curr;
> - unsigned long load;
> + unsigned long load, se_load;
>
> lag = se->vlag;
> -
> + se_load = scale_load_down(se->load.weight);
> /*
> * If we want to place a task and preserve lag, we have to
> * consider the effect of the new entity on the weighted
> @@ -5252,9 +5252,13 @@ place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
> if (curr && curr->on_rq)
> load += scale_load_down(curr->load.weight);
>
> - lag *= load + scale_load_down(se->load.weight);
> - if (WARN_ON_ONCE(!load))
> - load = 1;
> + lag *= load + se_load;
> + /*
> + * we just need to keep the lag whithout inflating it when the se is
> + * the first sched_entity queued on cfs_rq.
> + */
> + if (!load)
> + load = se_load;
> lag = div_s64(lag, load);
> }
>
> @@ -5304,6 +5308,12 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
> */
> update_load_avg(cfs_rq, se, UPDATE_TG | DO_ATTACH);
> se_update_runnable(se);
> +
> + /*
> + * we should update the weight of cfs_rq before update_cfs_group.
> + * Ensure we can get accurate shares of the cfs_rq when its weights changes.
> + */
> + account_entity_enqueue(cfs_rq, se);
> /*
> * XXX update_load_avg() above will have attached us to the pelt sum;
> * but update_cfs_group() here will re-adjust the weight and have to
> @@ -5318,8 +5328,6 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
> if (!curr)
> place_entity(cfs_rq, se, flags);
>
> - account_entity_enqueue(cfs_rq, se);
> -
> /* Entity has migrated, no longer consider this task hot */
> if (flags & ENQUEUE_MIGRATED)
> se->exec_start = 0;
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