sched_feat(UTIL_EST_FASTUP) has been added to easily disable the feature
in order to check for possibly related regressions. After 3 years, it has
never been used and no regression has been reported. Let remove it
and make fast increase a permanent behavior.
Signed-off-by: Vincent Guittot <[email protected]>
---
I haven't updated the chinese documentation which also refers to
UTIL_EST_FASTUP. IIUC, this will be updated afterward by the
Translations' maintainers.
Documentation/scheduler/schedutil.rst | 7 +++----
kernel/sched/fair.c | 8 +++-----
kernel/sched/features.h | 1 -
3 files changed, 6 insertions(+), 10 deletions(-)
diff --git a/Documentation/scheduler/schedutil.rst b/Documentation/scheduler/schedutil.rst
index 32c7d69fc86c..803fba8fc714 100644
--- a/Documentation/scheduler/schedutil.rst
+++ b/Documentation/scheduler/schedutil.rst
@@ -90,8 +90,8 @@ For more detail see:
- Documentation/scheduler/sched-capacity.rst:"1. CPU Capacity + 2. Task utilization"
-UTIL_EST / UTIL_EST_FASTUP
-==========================
+UTIL_EST
+========
Because periodic tasks have their averages decayed while they sleep, even
though when running their expected utilization will be the same, they suffer a
@@ -99,8 +99,7 @@ though when running their expected utilization will be the same, they suffer a
To alleviate this (a default enabled option) UTIL_EST drives an Infinite
Impulse Response (IIR) EWMA with the 'running' value on dequeue -- when it is
-highest. A further default enabled option UTIL_EST_FASTUP modifies the IIR
-filter to instantly increase and only decay on decrease.
+highest. UTIL_EST filters to instantly increase and only decay on decrease.
A further runqueue wide sum (of runnable tasks) is maintained of:
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 34fe6e9490c2..146329678cb8 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4870,11 +4870,9 @@ static inline void util_est_update(struct cfs_rq *cfs_rq,
* to smooth utilization decreases.
*/
ue.enqueued = task_util(p);
- if (sched_feat(UTIL_EST_FASTUP)) {
- if (ue.ewma < ue.enqueued) {
- ue.ewma = ue.enqueued;
- goto done;
- }
+ if (ue.ewma < ue.enqueued) {
+ ue.ewma = ue.enqueued;
+ goto done;
}
/*
diff --git a/kernel/sched/features.h b/kernel/sched/features.h
index a3ddf84de430..143f55df890b 100644
--- a/kernel/sched/features.h
+++ b/kernel/sched/features.h
@@ -83,7 +83,6 @@ SCHED_FEAT(WA_BIAS, true)
* UtilEstimation. Use estimated CPU utilization.
*/
SCHED_FEAT(UTIL_EST, true)
-SCHED_FEAT(UTIL_EST_FASTUP, true)
SCHED_FEAT(LATENCY_WARN, false)
--
2.34.1
On 27/11/2023 15:32, Vincent Guittot wrote:
> sched_feat(UTIL_EST_FASTUP) has been added to easily disable the feature
> in order to check for possibly related regressions. After 3 years, it has
> never been used and no regression has been reported. Let remove it
> and make fast increase a permanent behavior.
>
> Signed-off-by: Vincent Guittot <[email protected]>
> ---
>
> I haven't updated the chinese documentation which also refers to
> UTIL_EST_FASTUP. IIUC, this will be updated afterward by the
> Translations' maintainers.
>
> Documentation/scheduler/schedutil.rst | 7 +++----
> kernel/sched/fair.c | 8 +++-----
> kernel/sched/features.h | 1 -
> 3 files changed, 6 insertions(+), 10 deletions(-)
LGTM.
Reviewed-by: Dietmar Eggemann <[email protected]>
On 27/11/2023 14:32, Vincent Guittot wrote:
> sched_feat(UTIL_EST_FASTUP) has been added to easily disable the feature
> in order to check for possibly related regressions. After 3 years, it has
> never been used and no regression has been reported. Let remove it
> and make fast increase a permanent behavior.
>
> Signed-off-by: Vincent Guittot <[email protected]>
> ---
>
> I haven't updated the chinese documentation which also refers to
> UTIL_EST_FASTUP. IIUC, this will be updated afterward by the
> Translations' maintainers.
Here it is in case you have to provide the translation:
diff --git a/Documentation/translations/zh_CN/scheduler/schedutil.rst
b/Documentation/translations/zh_CN/scheduler/schedutil.rst
index d1ea68007520..7c8d87f21c42 100644
--- a/Documentation/translations/zh_CN/scheduler/schedutil.rst
+++ b/Documentation/translations/zh_CN/scheduler/schedutil.rst
@@ -89,16 +89,15 @@
r_cpu被定义为当前CPU的最高性能水平与系统中任何其它CPU的最
- Documentation/translations/zh_CN/scheduler/sched-capacity.rst:"1.
CPU Capacity + 2. Task utilization"
-UTIL_EST / UTIL_EST_FASTUP
-==========================
+UTIL_EST
+========
由于周期性任务的平均数在睡眠时会衰减，而在运行时其预期利用率会和睡眠前相同，
因此它们在再次运行后会面临（DVFS）的上涨。
为了缓解这个问题，（一个默认使能的编译选项）UTIL_EST驱动一个无限脉冲响应
（Infinite Impulse Response，IIR）的EWMA，“运行”值在出队时是最高的。
-另一个默认使能的编译选项UTIL_EST_FASTUP修改了IIR滤波器，使其允许立即增加，
-仅在利用率下降时衰减。
+UTIL_EST滤波使其在遇到更高值时立刻增加，而遇到低值时会缓慢衰减。
进一步，运行队列的（可运行任务的）利用率之和由下式计算：
>
> Documentation/scheduler/schedutil.rst | 7 +++----
> kernel/sched/fair.c | 8 +++-----
> kernel/sched/features.h | 1 -
> 3 files changed, 6 insertions(+), 10 deletions(-)
>
> diff --git a/Documentation/scheduler/schedutil.rst b/Documentation/scheduler/schedutil.rst
> index 32c7d69fc86c..803fba8fc714 100644
> --- a/Documentation/scheduler/schedutil.rst
> +++ b/Documentation/scheduler/schedutil.rst
> @@ -90,8 +90,8 @@ For more detail see:
> - Documentation/scheduler/sched-capacity.rst:"1. CPU Capacity + 2. Task utilization"
>
>
> -UTIL_EST / UTIL_EST_FASTUP
> -==========================
> +UTIL_EST
> +========
>
> Because periodic tasks have their averages decayed while they sleep, even
> though when running their expected utilization will be the same, they suffer a
> @@ -99,8 +99,7 @@ though when running their expected utilization will be the same, they suffer a
>
> To alleviate this (a default enabled option) UTIL_EST drives an Infinite
> Impulse Response (IIR) EWMA with the 'running' value on dequeue -- when it is
> -highest. A further default enabled option UTIL_EST_FASTUP modifies the IIR
> -filter to instantly increase and only decay on decrease.
> +highest. UTIL_EST filters to instantly increase and only decay on decrease.
>
> A further runqueue wide sum (of runnable tasks) is maintained of:
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 34fe6e9490c2..146329678cb8 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -4870,11 +4870,9 @@ static inline void util_est_update(struct cfs_rq *cfs_rq,
> * to smooth utilization decreases.
> */
> ue.enqueued = task_util(p);
> - if (sched_feat(UTIL_EST_FASTUP)) {
> - if (ue.ewma < ue.enqueued) {
> - ue.ewma = ue.enqueued;
> - goto done;
> - }
> + if (ue.ewma < ue.enqueued) {
> + ue.ewma = ue.enqueued;
> + goto done;
> }
>
> /*
> diff --git a/kernel/sched/features.h b/kernel/sched/features.h
> index a3ddf84de430..143f55df890b 100644
> --- a/kernel/sched/features.h
> +++ b/kernel/sched/features.h
> @@ -83,7 +83,6 @@ SCHED_FEAT(WA_BIAS, true)
> * UtilEstimation. Use estimated CPU utilization.
> */
> SCHED_FEAT(UTIL_EST, true)
> -SCHED_FEAT(UTIL_EST_FASTUP, true)
>
> SCHED_FEAT(LATENCY_WARN, false)
>
Reviewed-by: Hongyan Xia <[email protected]>
On Fri, Dec 1, 2023 at 4:30 AM Hongyan Xia <[email protected]> wrote:
>
> Here it is in case you have to provide the translation:
>
> diff --git a/Documentation/translations/zh_CN/scheduler/schedutil.rst
> b/Documentation/translations/zh_CN/scheduler/schedutil.rst
> index d1ea68007520..7c8d87f21c42 100644
> --- a/Documentation/translations/zh_CN/scheduler/schedutil.rst
> +++ b/Documentation/translations/zh_CN/scheduler/schedutil.rst
> @@ -89,16 +89,15 @@
> r_cpu被定义为当前CPU的最高性能水平与系统中任何其它CPU的最
> - Documentation/translations/zh_CN/scheduler/sched-capacity.rst:"1.
> CPU Capacity + 2. Task utilization"
>
>
> -UTIL_EST / UTIL_EST_FASTUP
> -==========================
> +UTIL_EST
> +========
>
>
> 由于周期性任务的平均数在睡眠时会衰减，而在运行时其预期利用率会和睡眠前相同，
> 因此它们在再次运行后会面临（DVFS）的上涨。
>
> 为了缓解这个问题，（一个默认使能的编译选项）UTIL_EST驱动一个无限脉冲响应
> （Infinite Impulse Response，IIR）的EWMA，“运行”值在出队时是最高的。
> -另一个默认使能的编译选项UTIL_EST_FASTUP修改了IIR滤波器，使其允许立即增加，
> -仅在利用率下降时衰减。
> +UTIL_EST滤波使其在遇到更高值时立刻增加，而遇到低值时会缓慢衰减。
>
Hi Hongyan,
Thanks for your Chinese documentation translation!
For the translation:
Reviewed-by: Tang Yizhou <[email protected]>
Thanks,
Yizhou
On Thu, 30 Nov 2023 at 21:30, Hongyan Xia <[email protected]> wrote:
>
> On 27/11/2023 14:32, Vincent Guittot wrote:
> > sched_feat(UTIL_EST_FASTUP) has been added to easily disable the feature
> > in order to check for possibly related regressions. After 3 years, it has
> > never been used and no regression has been reported. Let remove it
> > and make fast increase a permanent behavior.
> >
> > Signed-off-by: Vincent Guittot <[email protected]>
> > ---
> >
> > I haven't updated the chinese documentation which also refers to
> > UTIL_EST_FASTUP. IIUC, this will be updated afterward by the
> > Translations' maintainers.
>
> Here it is in case you have to provide the translation:
>
> diff --git a/Documentation/translations/zh_CN/scheduler/schedutil.rst
> b/Documentation/translations/zh_CN/scheduler/schedutil.rst
> index d1ea68007520..7c8d87f21c42 100644
> --- a/Documentation/translations/zh_CN/scheduler/schedutil.rst
> +++ b/Documentation/translations/zh_CN/scheduler/schedutil.rst
> @@ -89,16 +89,15 @@
> r_cpu被定义为当前CPU的最高性能水平与系统中任何其它CPU的最
> - Documentation/translations/zh_CN/scheduler/sched-capacity.rst:"1.
> CPU Capacity + 2. Task utilization"
>
>
> -UTIL_EST / UTIL_EST_FASTUP
> -==========================
> +UTIL_EST
> +========
>
>
> 由于周期性任务的平均数在睡眠时会衰减，而在运行时其预期利用率会和睡眠前相同，
> 因此它们在再次运行后会面临（DVFS）的上涨。
>
> 为了缓解这个问题，（一个默认使能的编译选项）UTIL_EST驱动一个无限脉冲响应
> （Infinite Impulse Response，IIR）的EWMA，“运行”值在出队时是最高的。
> -另一个默认使能的编译选项UTIL_EST_FASTUP修改了IIR滤波器，使其允许立即增加，
> -仅在利用率下降时衰减。
> +UTIL_EST滤波使其在遇到更高值时立刻增加，而遇到低值时会缓慢衰减。
>
> 进一步，运行队列的（可运行任务的）利用率之和由下式计算：
>
Thanks.
I will add it to the next version
> >
> > Documentation/scheduler/schedutil.rst | 7 +++----
> > kernel/sched/fair.c | 8 +++-----
> > kernel/sched/features.h | 1 -
> > 3 files changed, 6 insertions(+), 10 deletions(-)
> >
> > diff --git a/Documentation/scheduler/schedutil.rst b/Documentation/scheduler/schedutil.rst
> > index 32c7d69fc86c..803fba8fc714 100644
> > --- a/Documentation/scheduler/schedutil.rst
> > +++ b/Documentation/scheduler/schedutil.rst
> > @@ -90,8 +90,8 @@ For more detail see:
> > - Documentation/scheduler/sched-capacity.rst:"1. CPU Capacity + 2. Task utilization"
> >
> >
> > -UTIL_EST / UTIL_EST_FASTUP
> > -==========================
> > +UTIL_EST
> > +========
> >
> > Because periodic tasks have their averages decayed while they sleep, even
> > though when running their expected utilization will be the same, they suffer a
> > @@ -99,8 +99,7 @@ though when running their expected utilization will be the same, they suffer a
> >
> > To alleviate this (a default enabled option) UTIL_EST drives an Infinite
> > Impulse Response (IIR) EWMA with the 'running' value on dequeue -- when it is
> > -highest. A further default enabled option UTIL_EST_FASTUP modifies the IIR
> > -filter to instantly increase and only decay on decrease.
> > +highest. UTIL_EST filters to instantly increase and only decay on decrease.
> >
> > A further runqueue wide sum (of runnable tasks) is maintained of:
> >
> > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> > index 34fe6e9490c2..146329678cb8 100644
> > --- a/kernel/sched/fair.c
> > +++ b/kernel/sched/fair.c
> > @@ -4870,11 +4870,9 @@ static inline void util_est_update(struct cfs_rq *cfs_rq,
> > * to smooth utilization decreases.
> > */
> > ue.enqueued = task_util(p);
> > - if (sched_feat(UTIL_EST_FASTUP)) {
> > - if (ue.ewma < ue.enqueued) {
> > - ue.ewma = ue.enqueued;
> > - goto done;
> > - }
> > + if (ue.ewma < ue.enqueued) {
> > + ue.ewma = ue.enqueued;
> > + goto done;
> > }
> >
> > /*
> > diff --git a/kernel/sched/features.h b/kernel/sched/features.h
> > index a3ddf84de430..143f55df890b 100644
> > --- a/kernel/sched/features.h
> > +++ b/kernel/sched/features.h
> > @@ -83,7 +83,6 @@ SCHED_FEAT(WA_BIAS, true)
> > * UtilEstimation. Use estimated CPU utilization.
> > */
> > SCHED_FEAT(UTIL_EST, true)
> > -SCHED_FEAT(UTIL_EST_FASTUP, true)
> >
> > SCHED_FEAT(LATENCY_WARN, false)
> >
>
> Reviewed-by: Hongyan Xia <[email protected]>
On Fri, 1 Dec 2023 at 03:16, Tang Yizhou <[email protected]> wrote:
>
> On Fri, Dec 1, 2023 at 4:30 AM Hongyan Xia <[email protected]> wrote:
> >
> > Here it is in case you have to provide the translation:
> >
> > diff --git a/Documentation/translations/zh_CN/scheduler/schedutil.rst
> > b/Documentation/translations/zh_CN/scheduler/schedutil.rst
> > index d1ea68007520..7c8d87f21c42 100644
> > --- a/Documentation/translations/zh_CN/scheduler/schedutil.rst
> > +++ b/Documentation/translations/zh_CN/scheduler/schedutil.rst
> > @@ -89,16 +89,15 @@
> > r_cpu被定义为当前CPU的最高性能水平与系统中任何其它CPU的最
> > - Documentation/translations/zh_CN/scheduler/sched-capacity.rst:"1.
> > CPU Capacity + 2. Task utilization"
> >
> >
> > -UTIL_EST / UTIL_EST_FASTUP
> > -==========================
> > +UTIL_EST
> > +========
> >
> >
> > 由于周期性任务的平均数在睡眠时会衰减，而在运行时其预期利用率会和睡眠前相同，
> > 因此它们在再次运行后会面临（DVFS）的上涨。
> >
> > 为了缓解这个问题，（一个默认使能的编译选项）UTIL_EST驱动一个无限脉冲响应
> > （Infinite Impulse Response，IIR）的EWMA，“运行”值在出队时是最高的。
> > -另一个默认使能的编译选项UTIL_EST_FASTUP修改了IIR滤波器，使其允许立即增加，
> > -仅在利用率下降时衰减。
> > +UTIL_EST滤波使其在遇到更高值时立刻增加，而遇到低值时会缓慢衰减。
> >
>
> Hi Hongyan,
>
> Thanks for your Chinese documentation translation!
>
> For the translation:
> Reviewed-by: Tang Yizhou <[email protected]>
Thanks
>
> Thanks,
> Yizhou