sched_ext: Remove scx_ops_allow_queued_wakeup static_key

scx_ops_allow_queued_wakeup is used to encode SCX_OPS_ALLOW_QUEUED_WAKEUP
into a static_key. The test is gated behind scx_enabled(), and, even when
sched_ext is enabled, is unlikely for the static_key usage to make any
meaningful difference. It is made to use a static_key mostly because there
was no reason not to. However, global static_keys can't work with the
planned hierarchical multiple scheduler support. Remove the static_key and
instead test SCX_OPS_ALLOW_QUEUED_WAKEUP directly.

In repeated hackbench runs before and after static_keys removal on an AMD
Ryzen 3900X, I couldn't tell any measurable performance difference.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Changwoo Min <changwoo@igalia.com>
Acked-by: Andrea Righi <arighi@nvidia.com>

1 files changed, 1 insertions, 7 deletions

diff --git a/kernel/sched/ext.h b/kernel/sched/ext.h
index 1bda96b19a1b..3053cdd61eb9 100644
--- a/kernel/sched/ext.h
+++ b/kernel/sched/ext.h
@@ -21,6 +21,7 @@ void scx_rq_activate(struct rq *rq);
 void scx_rq_deactivate(struct rq *rq);
 int scx_check_setscheduler(struct task_struct *p, int policy);
 bool task_should_scx(int policy);
+bool scx_allow_ttwu_queue(const struct task_struct *p);
 void init_sched_ext_class(void);
 
 static inline u32 scx_cpuperf_target(s32 cpu)
@@ -36,13 +37,6 @@ static inline bool task_on_scx(const struct task_struct *p)
 	return scx_enabled() && p->sched_class == &ext_sched_class;
 }
 
-static inline bool scx_allow_ttwu_queue(const struct task_struct *p)
-{
-	return !scx_enabled() ||
-		static_branch_likely(&scx_ops_allow_queued_wakeup) ||
-		p->sched_class != &ext_sched_class;
-}
-
 #ifdef CONFIG_SCHED_CORE
 bool scx_prio_less(const struct task_struct *a, const struct task_struct *b,
 		   bool in_fi);