Commit-ID: 4a465e3ebbc8004ce4f7f08f6022ee8315a94edf
Gitweb: https://git.kernel.org/tip/4a465e3ebbc8004ce4f7f08f6022ee8315a94edf
Author: Dietmar Eggemann <dietmar.eggemann@xxxxxxx>
AuthorDate: Fri, 3 Aug 2018 15:05:38 +0100
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Tue, 2 Oct 2018 09:45:03 +0200
sched/fair: Remove setting task's se->runnable_weight during PELT update
A CFS (SCHED_OTHER, SCHED_BATCH or SCHED_IDLE policy) task's
se->runnable_weight must always be in sync with its se->load.weight.
se->runnable_weight is set to se->load.weight when the task is
forked (init_entity_runnable_average()) or reniced (reweight_entity()).
There are two cases in set_load_weight() which since they currently only
set se->load.weight could lead to a situation in which se->load.weight
is different to se->runnable_weight for a CFS task:
(1) A task switches to SCHED_IDLE.
(2) A SCHED_FIFO, SCHED_RR or SCHED_DEADLINE task which has been reniced
(during which only its static priority gets set) switches to
SCHED_OTHER or SCHED_BATCH.
Set se->runnable_weight to se->load.weight in these two cases to prevent
this. This eliminates the need to explicitly set it to se->load.weight
during PELT updates in the CFS scheduler fastpath.
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@xxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Joel Fernandes <joelaf@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Morten Rasmussen <morten.rasmussen@xxxxxxx>
Cc: Patrick Bellasi <patrick.bellasi@xxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Quentin Perret <quentin.perret@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/20180803140538.1178-1-dietmar.eggemann@xxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/sched/core.c | 2 ++
kernel/sched/pelt.c | 6 ------
2 files changed, 2 insertions(+), 6 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index f2caf1bae4a3..56b3c1781276 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -700,6 +700,7 @@ static void set_load_weight(struct task_struct *p, bool update_load)
if (idle_policy(p->policy)) {
load->weight = scale_load(WEIGHT_IDLEPRIO);
load->inv_weight = WMULT_IDLEPRIO;
+ p->se.runnable_weight = load->weight;
return;
}
@@ -712,6 +713,7 @@ static void set_load_weight(struct task_struct *p, bool update_load)
} else {
load->weight = scale_load(sched_prio_to_weight[prio]);
load->inv_weight = sched_prio_to_wmult[prio];
+ p->se.runnable_weight = load->weight;
}
}
diff --git a/kernel/sched/pelt.c b/kernel/sched/pelt.c
index 48a126486435..90fb5bc12ad4 100644
--- a/kernel/sched/pelt.c
+++ b/kernel/sched/pelt.c
@@ -269,9 +269,6 @@ ___update_load_avg(struct sched_avg *sa, unsigned long load, unsigned long runna
int __update_load_avg_blocked_se(u64 now, int cpu, struct sched_entity *se)
{
- if (entity_is_task(se))
- se->runnable_weight = se->load.weight;
-
if (___update_load_sum(now, cpu, &se->avg, 0, 0, 0)) {
___update_load_avg(&se->avg, se_weight(se), se_runnable(se));
return 1;
@@ -282,9 +279,6 @@ int __update_load_avg_blocked_se(u64 now, int cpu, struct sched_entity *se)
int __update_load_avg_se(u64 now, int cpu, struct cfs_rq *cfs_rq, struct sched_entity *se)
{
- if (entity_is_task(se))
- se->runnable_weight = se->load.weight;
-
if (___update_load_sum(now, cpu, &se->avg, !!se->on_rq, !!se->on_rq,
cfs_rq->curr == se)) {
|