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 <vincent.guittot@xxxxxxxxxx>
---
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
