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Subject[PATCH 6/7] sched/fair: Remove on_null_domain() and redundant checks
Date
CPUs with a NULL sched domain are removed from the HKR_TYPE_SCHED
isolation mask. The two following checks are equialent:
- !housekeeping_runtime_test_cpu(cpu, HKR_TYPE_SCHED)
- on_null_domain(rq)

Remove on_null_domain() and the redundant checks.

Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
---
kernel/sched/fair.c | 18 ++++++------------
1 file changed, 6 insertions(+), 12 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 3e0f2a0f153f..9657c8f2176b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -11830,11 +11830,6 @@ static void sched_balance_domains(struct rq *rq, enum cpu_idle_type idle)

}

-static inline int on_null_domain(struct rq *rq)
-{
- return unlikely(!rcu_dereference_sched(rq->sd));
-}
-
#ifdef CONFIG_NO_HZ_COMMON
/*
* NOHZ idle load balancing (ILB) details:
@@ -12040,7 +12035,7 @@ void nohz_balance_exit_idle(struct rq *rq)
SCHED_WARN_ON(rq != this_rq());

/* If we're a completely isolated CPU, we don't play: */
- if (on_null_domain(rq))
+ if (!housekeeping_runtime_test_cpu(cpu_of(rq), HKR_TYPE_SCHED))
return;

if (likely(!rq->nohz_tick_stopped))
@@ -12090,12 +12085,8 @@ void nohz_balance_enter_idle(int cpu)
*/
rq->has_blocked_load = 1;

- /* Spare idle load balancing on CPUs that don't want to be disturbed: */
- if (!housekeeping_runtime_test_cpu(cpu, HKR_TYPE_SCHED))
- return;
-
/* If we're a completely isolated CPU, we don't play: */
- if (on_null_domain(rq))
+ if (!housekeeping_runtime_test_cpu(cpu, HKR_TYPE_SCHED))
return;

/*
@@ -12504,11 +12495,14 @@ static __latent_entropy void sched_balance_softirq(struct softirq_action *h)
*/
void sched_balance_trigger(struct rq *rq)
{
+ int cpu = cpu_of(rq);
+
/*
* Don't need to rebalance while attached to NULL domain or
* runqueue CPU is not active
*/
- if (unlikely(on_null_domain(rq) || !cpu_active(cpu_of(rq))))
+ if (unlikely(!housekeeping_runtime_test_cpu(cpu, HKR_TYPE_SCHED)) ||
+ !cpu_active(cpu))
return;

if (time_after_eq(jiffies, rq->next_balance))
--
2.25.1

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